review article - j-stage

Therapeutic effects of polaprezinc (zinc L-carnosine complex) on pressure ulcer―A comparison with L-carnosine alone―

Kensaku Sakae and Hiroyuki Yanagisawa

Department of Public Health and Environmental Medicine, The Jikei University School of Medicine,

3-25-8 Nishishimbashi, Minato-ku, Tokyo 105-8461, JapanAbstractThe management of pressure ulcers (PUs) has become increasingly important in the setting of an aging population. Nutritional approach is essential for patients with PUs, although there is currently limited evidence supporting nutritional interventions for PU treatment. Zinc is widely accepted to play a crucial role in wound healing, whereas there is as yet no evidence for the efficacy of oral zinc therapy (in the form of zinc alone) in PU healing. Most recently, we reported the therapeutic effects of polaprezinc (zinc L-carnosine complex) on PU, along with those of L-carnosine alone. L-carnosine is an endogenous dipeptide (comprised of β-alanine and L-histidine) and possesses many biological functions. Therefore, L-carnosine has recently been hypothesized to have potential therapeutic benefits for a considerable spectrum of age-related diseases. Its zinc complex polaprezinc has been a commonly prescribed medication for gastric ulcers in Japan since 1994. In the treatment of PUs, the potency of L-carnosine was far greater than we expected. Polaprezinc was more potent than L-carnosine, but did not differ significantly. Accordingly, whether oral zinc exerts a therapeutic benefit remained unclear from our finding as well as other past studies. This review article summarizes the results of our two clinical trials; part 1 was a 4-week nonrandomized controlled trial designed to examine the efficacies of polaprezinc and L-carnosine and to compare the potency of two agents; and part 2 was a case series for evaluating the efficacy and safety of maximum 8-week polaprezinc treatment. Polaprezinc is a tablet and therefore easy-to-use, as compared to high-protein/energy beverages that have often been used for PU treatment. It can be a novel therapeutic option for PUs as their oral treatment. We finally provide a perspective of future research.

Key Words : pressure ulcer, polaprezinc, zinc, L-carnosine

Review Article

underlying diseases, can also predispose an individual to PUs [1, 2]. Once PUs develop, they reduce quality of life for patients and can even be life-threatening. PU prevalence is now widespread depending on treatment settings, with estimates of a few percent to up to around 30% [3-5]. There is a trend that can only worsen as the lifespan increases hereafter. 　Nutritional approach is essential for the management of PUs. Guidelines set by the National Pressure Ulcer Advisory Panel (NPUAP) and the European Pressure Ulcer Advisory Panel (EPUAP) recommend that individuals with PUs are provided sufficient calories of 30-35 kcal/kg body weight, adequate protein of 1.25-1.5 g/kg body weight, and, if deficiencies are present, adequate vitamins and minerals [1]. So far nutritional-intervention trials for PU treatment have been conducted mainly using the following: high protein/energy beverages; those enriched with a mixture of specific nutrients, including arginine, zinc (Zn), and

Address correspondence to : Hiroyuki Yanagisawa, M.D., Ph.D.Department of Public Health and Environmental Medicine, The Jikei University School of Medicine, 3-25-8 Nishishimbashi, Minato-ku, Tokyo 105-8461, Japan Tel : 03-3433-1111 (2266)　　　

Fax : 03-5472-7526 E-mail : [email protected]

Introduction　

　Pressure ulcers (PUs) are a common and costly healthcare problem worldwide. PU is defined as “localized injury to the skin and/or underlying tissue usually over a bony prominence, as a result of pressure, or pressure in combination with shear” [1]. Meanwhile, many other factors, including advanced age, malnutrition, and deterioration of

106Biomed Res Trace Elements 25（3）：106-118, 2014

Received: 26 September 2014

Accepted: 3 October 2014

antioxidant vitamins; ZnSO4 alone; and ascorbic acid alone. Despite the above recommendation by guidelines, a latest systematic review concludes that there is currently no clear evidence of a benefit associated with nutritional interventions for PU treatment [6]. 　Most recently, we reported the therapeutic effects of polaprezinc (PLZ), a Zn L-carnosine (CAR) complex, on PU, along with those of CAR alone [7, 8]. Both these agents revealed significant potencies and strongly suggested to become novel treatments for PUs. Based on these our findings, this review article discusses (i) the usefulness of PLZ and CAR in the treatment of PUs and (ii) a comparison between the therapeutic effects of the two agents, and finally provides a perspective of future research.

Zinc　

　Zn is an essential trace element to serve as the active center of approximately 300 enzymes in humans. Zn deficiency, therefore, leads to various clinical symptoms and diseases, and delayed wound healing is the typical one included in them [9]. Zn is required by numerous enzymes or transcription factors that are involved in cell replication, protein synthesis, and repair systems after injury [10, 11]. It also has diverse effects on immune functions [12]. Thus, Zn plays a crucial role in wound healing. In clinical practice, Zn has been more commonly administered topically relative to systemically for skin wounds, e.g., as Zn oxide ointment. On the other hand, the benefit of oral Zn therapy for wound healing has not been well established. A recent appraisal concludes that oral ZnSO4 does not appear to aid the healing of arterial and venous leg ulcers, but that all studies searched were small and of mediocre quality [13]. Optimum dose levels and durations for oral Zn therapy also have been not fully verified. High-dose, long-term oral Zn therapy can be problematic because it can interfere with the absorption of copper (Cu) and iron (Fe), and induce deficiencies of these elements [3, 14]. In patients with PUs, decreased serum or plasma Zn levels have often been observed, suggesting the existence of Zn deficiency in such patients. As yet there have been very few clinical trials designed to determine the efficacy of oral Zn therapy (in the form of Zn alone) for PU healing, and none have demonstrated a positive effect [3].

L-carnosine　　CAR is a naturally-occurring dipeptide (comprised of β-alanine and L-histidine) and is abundant in long-living cells such as those of muscle and nerves [15]. It possesses many biological functions, such as antioxidation,

antiglycation, pH buffering, metal ion-chelating, and antiaging activity [15]. Therefore, CAR is expected to have therapeutic potential in multiple age-related diseases, such as Alzheimer’s disease, Parkinson’s disease, stroke, secondary diabetic complications, osteoporosis, and cataract [15-21]. Furthermore, it has been reported to attenuate physical and mental fatigue in healthy individuals [22, 23]. CAR also has been found to promote the healing of surgical wounds in rat studies [24]. Possible mechanisms underlying the action of CAR in wound healing are its life-extending effect on fibroblasts [25], its stimulatory effect on nitric oxide production in endothelial cells [26], and its protective effect against oxidative stress implicated in the pathogenesis of non-healing ulcers [27]. CAR is now commercially available as a dietary supplement, usually with a daily dose of 130-600 mg [28].

Polaprezinc

　PLZ is an artificially produced derivative of CAR in which a Zn ion and CAR are bound in a 1-to-1 ratio to create a chelate compound (Figure 1) [29]. A synergistic effect of its two ingredients on wound healing is anticipated. An animal study previously showed that PLZ accelerated the healing of skin incisions [30]. In Japan, PLZ has been a commonly prescribed medication for gastric ulcers since 1994. A daily dose of 150 mg PLZ contains 34 mg Zn and 116 mg CAR. In other countries, PLZ are commercially available as a dietary supplement, usually with a daily dose of 75 mg [31].

107 Biomed Res Trace Elements 25（3）：106-118, 2014

Fig. 1 Chemical structural formulas

Trial-part 1 [7]

Methods

Patients and study design　The part 1was designed to examine the effects of CAR and PLZ on PU healing and to compare the potency of these two agents. This was a nonrandomized controlled trial with maximum 4-week follow-up. In order of recruitment, all 42 patients were allocated to one of three groups: control (n = 14), PLZ (n = 10), and CAR (n = 18). They were long-term inpatients or nursing home residents. 　The control group had no CAR and PLZ treatments for a 4-week study period (from weeks 0 to 4), although patients who had achieved healing before week 4 were excluded. The CAR group took 58 mg CAR (b.d., p.o.). The PLZ group took 75 mg PLZ (b.d., p.o.), which contained 58 mg CAR and 17 mg Zn. CAR and PLZ were administered until healing was complete or for a maximum of 4 weeks. Because patients with PUs that had healed before week 4 were excluded from the control group, the following patients were screened out of enrollment in the CAR and PLZ groups: PU severity at week 0 was lower than the lowest severity at week 0 in the control group. Thus, baseline PU severities differed minimally among the three groups. 　Inclusion criteria were: (i) ≥20 years of age; (ii) presence of at least one stage -Ⅱ , -Ⅲ , or -Ⅳ PU ≥4 weeks according to the classification system set by the NPUAP and EPUAP; (iii) an estimated surface area for one ulcer of ≤24 cm² as calculated with the formula: greatest length (head to toe) × greatest width (side to side) of the ulcer; and (iv) capable of oral ingestion. Exclusion criteria were: (i) clinical suspicion or diagnosis of osteomyelitis; (ii) diabetes mellitus, peripheral vascular disease, malignant tumor, acute illness (e.g., infection), or other severe diseases; (iii) terminal phase of an illness; (iv) corticosteroid use; and (v) receiving tube or parenteral feeding (these factors can affect healing, and consent capability for study participation is limited in patients receiving tube or parenteral feeding).　Throughout the study, all patients received the same topical treatment and PU care. All patients ate their own diets and took their medications without alteration, except for temporary oral antibiotic therapy for acute infectious complications that developed after study commencement. Some patients received high-protein/energy beverages in addition to their standard hospital or institutional diets to meet each individual’s energy and protein requirements. 　Assessments were made once a week for PU severity and daily for dietary intake. Blood biochemical analyses were performed according to a schedule described below. All of

these evaluations ended at the endpoint of healing.

Pressure ulcer care　Several factors that can inhibit healing were dealt with by the start of this study. Ulcer infection had been controlled adequately, and the following factors removed by surgical debridement: (i) undermined or hypertrophic wound edge, (ii) hard and fibrotic granulation tissue, (iii) excessive granulation tissue proliferating beyond the edge and/or much higher than the skin surface, and (iv) necrotic tissue (removed to the maximum extent possible). Following a major debridement, patients underwent a preparation period of at least 10 to 14 days before the start of the study. 　All patients received similar PU care throughout the study according to standard protocols used in the hospital wards. Local pressure over the areas was reduced using a repositioning regimen, an alternating pressure air mattress on the bed, and a pressure-redistributing seat cushion when sitting in a chair. Topical treatment was standardized: (i) apply a mixture of sucrose and povidone-iodine (Povidorine Pasta Ointment; TOA Pharmaceuticals Co., Ltd., Toyama, Japan) to the ulcer, (ii) cover with a silver-containing Hydrofiber® Wound Dressing (Aquacel Ag, ConvaTec Inc., Skillman, NJ, USA), and (iii) seal the entire area with an adhesive polyurethane film. The mixture of sucrose and povidone-iodine has an antimicrobial effect [32]. Silver-containing Hydrofiber Wound Dressing is a moisture-retention dressing that forms a gel upon contact with wound fluid, and has the antimicrobial properties of ionic silver [33].　Additionally, after study commencement, necrotic and excessive granulation tissues were removed as extensively as possible if present, with immediate removal of any undermining. Furthermore, careful repositioning was carried out, focusing particularly on relief of shear, because it often causes undermining.

Pressure ulcer measurements　Nurses, who were well-trained and blinded to the treatment interventions, assessed PU severity once a week using the Pressure Ulcer Scale for Healing (PUSH tool 3.0) [34]. Categorical subscores for surface area (length × width) (0 to 10), amount of exudate (0 to 3), and type of wound tissue (0 to 4) were determined and combined to derive a total score from 0 (completely healed) to 17 (greatest severity). In cases with multiple PUs, the most severe ulcer was analyzed.

108 Pressure Ulcer and Polaprezinc

Assessment of pressure ulcer risk 　Baseline risk for PU development was assessed by the Braden scale [35]. Six subscores (sensory perception, moisture, activity, mobility, nutrition, and friction or shear) were determined and combined to derive a total score from 6 (highest risk) to 23 (lowest risk). Body weight measurement　The patients were weighed at weeks 0 and 4. Patients who had complete healing or dropped out before week 4 were weighed at that point, and the result was carried forward to week 4. For bedridden patients, a stretcher-chair scale was used.

Assessment of dietary intake　Dietary intakes during the study period were assessed daily by nurses at three main meals (breakfast, lunch, dinner) for all patients. Meal ingestion was recorded on a consumption scale of 0 (nothing consumed) to 10 (all consumed), individually for each food item and caloric beverage. Nurses were well-trained and given visual

guidelines for estimating meal intake from a dietitian. Based on these records, the mean daily intakes of energy, protein, Zn, Cu, Fe, vitamins A, C, and E were computed manually using the Standard Tables of Food Composition in Japan [36]. For energy and protein, the mean daily intakes per kg body weight were also calculated.

Blood biochemistry 　For each group, blood biochemistry was assessed at defined time points: for the control group, at weeks 0 and 4; for the CAR group, at weeks 0 (just before the start of CAR) and 4; for the PLZ group, at weeks 0 (just before the start of PLZ), and 1–4. If a patient had complete healing or dropped out at a time point other than the ones mentioned above, biochemistry data were also obtained at that point. 　Complete blood count, liver function tests as well as serum levels of transthyretin, C-reactive protein (CRP), urea, creatinine, electrolytes, uric acid, total cholesterol, high-density lipoprotein cholesterol (HDL-C), Zn, Cu, and Fe were measured. All blood parameters were obtained in the fasted state between 6 am and 8 am. All biochemical


Table 1. Baseline characteristics of patients of each group (trial-part 1)

CAR, L-carnosine; PLZ, polaprezinc; PUSH, Pressure Ulcer Scale for Healing. *Use of high-protein/energy beverages. Statistical comparisons among three groups were performed by one-way ANOVA, Kruskal-Wallis test (for not normal distribution), or Fisher’s exact test (for categorical variables). Data represent mean ± SD; ranges in parentheses.

data were measured by a commercial laboratory (Mitsubishi Chemical Medience Corporation, Tokyo, Japan).

ResultsBaseline characteristics　The baseline characteristics of the population are presented in Table 1. At baseline, no significant differences were found among groups in the demographic and nutritional parameters, the level of PU risk, and PU characteristics (severity, size, and staging), except for PU location. Furthermore, usage rates of high-protein/energy beverages were comparable. Two of the 42 patients dropped

out during this study, because they had pneumonia at week 1 (PLZ group) and week 2 (CAR group).

Changes in body weight 　During the study, there were no significant changes in body weight in any of the three groups. In addition, there were no significant differences among groups in weight at week 4. Pressure ulcer assessment　Figure 2 shows the changes in PU severity in all patients; the data are presented as least squares means ± SEM of


Fig. 2 Changes in PUSH total score for all patients (trial-part 1). Data represent least squares mean ± SEM. CAR, L-carnosine; PLZ, polaprezinc; PUSH, Pressure Ulcer Scale for Healing.

Table 2. Mean weekly improvements in PUSH score in each group, individually for total score and subscores (trial-part 1)

CAR, L-carnosine; PLZ, polaprezinc; PUSH, Pressure Ulcer Scale for Healing. All pairwise comparisons among groups were performed by the Steel-Dwass test. *P<0.05, **P<0.01 vs control. Data represent mean ± SEM.

PUSH total scores. 　Table 2 shows the rate of PU healing as assessed by the mean weekly improvement (MWI) in PUSH total score, along with the MWI in each PUSH subscore. Control group patients showed an MWI in PUSH total score of 0.8 ± 0.2; CAR group patients, 1.6 ± 0.2 (P=0.02, vs control); and PLZ group patients, 1.8 ± 0.2 (P=0.009, vs control; P=0.73, vs CAR). Analyses for subscores showed significantly greater MWI in both CAR and PLZ groups compared with the control group in surface area and exudate amount scores. Differences between the CAR and PLZ groups were not significant for any subscores. 　As complementary analyses, comparisons between two groups (i.e., control vs CAR and control vs PLZ) for the MWI in PUSH total score were performed adjusting for baseline characteristics by stepwise multiple linear regression analysis. These analyses included group; sex; age; BMI; weight; Braden scale score; use of high-protein/energy beverages; size, stage, and location of PU; and PUSH total score as independent variables. The MWI in PUSH total score was the dependent variable. The criteria for variable selection were defined as P<0.15 both for entry into the model and for staying in the model. In Analysis 1, which compared the control group with the CAR group, the group variable was dichotomous, with 0 for the control group and 1 for the CAR group, and was independently and positively related to the MWI in PUSH total score (P=0.006, R²=0.224). In Analysis 2, which compared the control group with the PLZ group, the group variable was dichotomous, with 0 for the control group and 1 for the PLZ group, and was independently and positively related to the MWI in PUSH total score (P=0.001, R²=0.377).

Dietary intakes　Table 3 shows the mean daily dietary intakes of energy, protein, Zn, Cu, and Fe over the study period. There were no significant differences among the three groups in any of these nutrient intakes. For vitamins A, C, and E, there were no significant differences among the groups (data not shown).

Blood biochemistry　Table 4 shows changes in key biochemical parameters over the study period. There were no significant differences among the three groups in any of the baseline parameters. After CAR treatment, serum Zn, Cu, and Fe showed no significant changes. After PLZ treatment, serum Zn gradually and significantly increased, while serum Cu gradually and significantly decreased; serum Fe showed no changes. Serum transthyretin and albumin levels were below the reference range (RR: transthyretin, 22−40 mg/dL; albumin, 3.8−5.3 g/dL) and CRP was above RR (≤0.30 mg/dL) in all three groups; no significant changes in these parameters were noted over the study. On average, complete blood count, liver function tests (except albumin), urea, creatinine, electrolytes, uric acid, total cholesterol, and HDL-C showed little deviation from RR over the course of the study, with no significant changes (data not shown). However, one patient in the CAR group had moderate liver dysfunction at week 4.


Table 3. Mean daily dietary intakes over the study period (trial-part 1) ª

CAR, L-carnosine; PLZ, polaprezinc.ª Analysis of dietary intake includes contribution made by the high-protein/energy beverages. Between-group differences were tested by one-way ANOVA. No significant differences were found among groups in any nutrients. Data represent mean ± SEM.

Trial-part 2 [8]

Methods　

　The part 2 was conducted to further evaluate the efficacy and safety of PLZ in PU treatment with maximum 8-week follow-up. This was performed consecutively after the part 1. All 14 patients of the control group in part 1 were enrolled in part 2. After no CAR and PLZ treatments for a full 4 weeks in part 1, they took 75 mg PLZ (b.d., p.o.) until healing was complete or for a maximum of 8 weeks. 　Topical treatment, PU care, diets, and medications were all unchanged from part 1 for each patient. Blood biochemistry was assessed at week 0 (just before the start of PLZ administration), 1–4, 6, and 8. If a patient healed at a time point other than the ones mentioned above, biochemistry data were also obtained at that point. Patients’ weights were assessed at week 0 and a healing endpoint or at week 8 if the PU had not healed. PU severity and dietary intake were assessed by the same methods as in the part 1.

Results　

　Of 14 patients, 11 healed within 8 weeks. Eight patients healed within the first 4 weeks and the remaining six patients continued treatment afterwards. No patients dropped out of the study. Figure 3 shows the change in PU severity for all patients; data are presented as least squares mean values with 95% CI of PUSH total score. PUSH total scores improved from 8.1 [95% CI, 6.0–10.3] at baseline to −1.4 [95% CI, −4.0 to 1.1] at week 8, with a significant change during the entire 8 weeks (P<0.001). When adjusted for multiplicity, differences from baseline were significant from week 1 (P<0.05). The MWI in PUSH total score was 2.0 (± 0.3 SEM). The mean change in body weight during the study was −0.38 (± 0.36 SEM) kg with no significant change. 　Table 5 shows the changes in key biochemical parameters over the study period. Serum Zn levels increased gradually and significantly toward week 4 (P<0.01) and thereafter decreased toward week 8, but maintained significantly higher levels than baseline (P<0.05). Serum Cu levels decreased gradually and significantly toward week 8 (P=0.001). These changes resulted in marked decreases in the serum Cu/Zn


Table 4. Changes in biochemical parameters for each group (trial-part 1) a

CAR, L-carnosine; PLZ, polaprezinc.ª For simplicity, only the results at weeks 0 and 4 are listed. b Between-group differences at week 0 were tested by one-way ANOVA. c Within-group changes were tested including the data at non-listed time points by the mixed model; pairwise comparisons with week 0 were further made by Dunnett-Hsu test (*P<0.05, **P<0.01 vs week 0). Data represent least squares mean ± SEM.

ratio. Serum Fe levels showed no significant changes. Serum levels of alkaline phosphatase were within the RR (100–325 IU/L) at baseline and showed no significant changes. Serum levels of albumin and transthyretin were below the RR and CRP was above the RR. Serum levels of albumin and transthyretin showed slight (but significant, P<0.05) changes that probably resulted from transient infection/inflammation observed in this study. Complete blood count, liver function tests (except albumin), levels of urea, creatinine, electrolytes, uric acid, total cholesterol, and HDL-C showed little deviation from

the RRs during the study, with no significant changes (data not shown). Table 6 shows the mean daily dietary intakes of energy, protein, Zn, Cu, and Fe over the study period.

Discussion　From the results of trial-part 1, we successfully showed that during a 4-week period, CAR and PLZ improved the PU healing approximately 2- and 2.2-fold, respectively, than without CAR and PLZ treatments (MWI in PUSH total score: CAR, 1.6; PLZ, 1.8; control, 0.8). In general, clinical trials for PU are difficult to draw any conclusions. Its causes


Fig. 3 Changes in PUSH total score for all patients (trial-part 2). The change during the 8 weeks was significant (P<0.001, by the mixed model); differences from baseline were significant from week 1 (*P<0.05, **P<0.01 vs baseline, by the Dunnett–Hsu test). Data are the least squares mean with 95% CI. PUSH, Pressure Ulcer Scale for Healing.

Table 5. Changes in biochemical parameters (trial-part 2) a

ª For simplicity, only the results at weeks 0, 4, and 8 are listed. b Changes over the study period were tested including the data at non-listed time points by the mixed model; pairwise comparisons with week 0 were further made using the Dunnett–Hsu test (*P<0.05, **P<0.01 vs week 0). Data represent least squares mean ± SEM.

are due likely to the following variations: patients’ general conditions and underlying diseases; PU severity (size, depth, condition); use or nonuse of pressure-redistributing support surface; types of topical treatment applied; oral medications used; and dietary constituents. Especially, the condition of PUs can greatly affect the healing outcome and therefore should be adequately managed through before- and after-study commencement. 　For recent ten years, the “wound bed preparation” concept has been highlighted as an important aspect for the management of PUs [37]. It focuses on optimizing conditions at wound bed so as to accelerate endogenous healing or to facilitate the effects of other therapies, by removing barriers to healing. Such barriers are articulated as the acronym TIME (i.e., Tissue non-viable or deficient, Infection or inflammation, Moisture imbalance, Edge of wound non-advancing or undermined). According to this concept, our studies were performed removing the TIME, because they could hamper healing and consequently obscure a true therapeutic effect. Of the TIME, we particularly noted the T (fibrotic and senescent granulation tissue, or necrosis, with poor vascularization) and the E (undermined or hypertrophic wound edge) by which wound healing get stuck. 　To date, there is no evidence for the efficacy of oral Zn therapy (in the form of Zn alone) in PU healing. Only two clinical trials have addressed this question [38, 39]. Both of them were old ones, and used ZnSO4 at about 150 mg/day of elemental Zn. As a result, neither has shown a positive effect. However, these trials had no data on PU conditions, use of pressure-redistributing support surface, and blood sampling time necessary for evaluating patients’ serum Zn levels. Hence, the effects of oral Zn therapy appear to be inconclusive from the results of these trials.

　CAR has recently been hypothesized to have potential therapeutic benefits for a considerable spectrum of age-related diseases, as its biological functions have become extensively clear. The potency of CAR for PU healing observed in our study was far greater than we expected. This result was a little surprising for us who had thought the benefit of PLZ (a Zn-CAR complex) to be due primarily to Zn. The potency of PLZ was further greater than that of CAR, but did not differ significantly. Accordingly, we failed to show an obvious benefit of Zn from these results. Here there are two possibilities to take into account. One is that the great potency of CAR may have masked the potency of Zn if CAR had maximally accelerated the rate of PU healing. The other is that a longer follow-up period may have disclosed predominance of PLZ over CAR. To more clearly verify the benefit of Zn, future researches are desirable to compare inorganic Zn salts (e.g., ZnSO4) with untreated control, or to have up to 8-week follow-up period for comparing PLZ with CAR. 　The trial-part 2 was a case series with no control arms. Therefore, we used historical control data for comparison. The rate of PU healing during part 2 was compared with that during part 1 for the same 14 patients. They had no PLZ treatment for 4 weeks and then took PLZ treatment for 8 weeks. As a result, the PU healing accelerated approximately 2.5-fold after PLZ treatment (MWI in PUSH total score: during part 1, 0.8; during part 2, 2.0). This result is quite promising. However, given a non-parallel comparison, we must make allowances for the possibility that healing may have been affected by time. Meanwhile, this comparison of a time series overcomes the above-mentioned common problems of PU studies; that is, the healing of PUs varies among individuals, topical and oral medications used, or dietary constituents. From the result of trial-part 2, it


Table 6. Mean daily dietary intakes over the study period (trial-part 2)

Data are the mean ± SD.

is suggested that PLZ treatment for PUs may be also effective when administered for maximum 8 weeks. 　All 42 patients showed baseline serum Zn levels of a range of 32–102 μg/dL. According to the lower cutoff of the serum Zn level of 80 μg/dL in blood sampling in the morning proposed by the Japan Society for Biomedical Research on Trace Elements [40, 41], 36 of the 42 patients were Zn deficient. After PLZ treatment, serum Zn levels gradually increased, peaked after 4 weeks, and gradually declined toward 8 weeks, but sustained a significant increase than baseline. This is a unique pattern in the change of serum Zn level due to PLZ treatment. The overall increased serum Zn levels reveal the potential of PLZ for Zn repletion. Meanwhile, serum Cu levels and serum Cu/Zn ratios significantly decreased. In particular, preexisting Cu deficiency deteriorated in two patients (serum Cu: one in part 1, from 65 μg/dL to 48 μg/dL after 4 weeks; the other in part 2, from 51 μg/dL to 39 μg/dL after 5 weeks; RR, 70–132 μg/dL). Serum Fe levels were unchanged. 　For patients who received PLZ treatment, daily total Zn intakes (including PLZ) ranged from 38.05– 43.11 (mean, 40.72) mg in trial-part 1 and from 38.76–50.82 (mean, 41.65) mg in trial-part 2. The Institute of Medicine of the National Academy of Sciences sets the tolerable upper intake level of Zn of 40 mg/day in the Dietary Reference Intakes [42]. High-dose oral Zn therapy has been reported to induce gastrointestinal distress, impaired immune function, or decreased HDL-C, but these adverse events were not observed in our trials. Thus, the treatment of PUs with PLZ (containing 34 mg Zn) appears to be relatively safe, if paid attention to the decrease in serum Cu level. 　CAR treatment affected neither serum Zn, Cu, nor Fe levels. CAR accelerates Zn uptake from the intestine [43], although in our study CAR was unlikely to meaningfully increase the absorption of dietary Zn, considering the unaffected serum Zn levels. This finding indicates that the enhanced healing by CAR was not due to improved Zn status but rather to the potency of CAR alone. With regard to adverse events likely to be related to CAR, moderate liver dysfunction occurred after 4 weeks in one patient, but improved with ursodeoxycholic acid soon after stopping CAR. 　Specific nutrients (including energy, protein, Cu, Fe, vitamins A, C, and E) are conceptually related to PU healing [44]. In the trial-part 1, the actual intakes of these nutrients from diet did not differ significantly among the control, CAR, and PLZ groups. On the other hand,

guidelines by the NPUAP and EPUAP set the recommended daily allowance (RDA) of 30–35 kcal/kg/day and 1.25–1.5 g protein/kg/day for individuals with PUs [1]. Dietary intakes for our patients were 38.19 kcal/kg/day and 1.52 g protein/kg/day in trial-part 1; and 40.43 kcal/kg/day and 1.60 g protein/kg/day in trial-part 2. Therefore, they ingested the above RDA.　The main l imitation of tr ial-part 1 was lack of randomization. Although the allocation was done in order of recruitment (not arbitrarily), lack of randomization could be a confounding factor, given the small sample size. To address this issue, we reanalyzed the primary outcome data by multiple linear regression analysis and ascertained the positive effects of CAR and PLZ on PU healing after adjustment for baseline characteristics. 　Finally, we introduce an of interest in vitro study that indicated the possible physiological relevance of Zn for the action of CAR. It found that CAR-induced rabbit vascular vein contraction was blocked by the divalent cation chelator EDTA and potentiated by adding Zn, but none of several other transition metals. Thus, it raised the possibility that the effect of CAR is attributable to the formation of a Zn-CAR complex. In addition, the authors discussed that this finding might have implications for other systems where both CAR and Zn are present, as well as vascular vein [45].

Concluding remarks　Eight-week PLZ treatment for PUs may be effective and well-tolerated. However, the decrease in serum Cu level should be paid attention as an adverse event, particularly in patients with preexisting Cu deficiency. In such cases, it seems better that Cu-rich foods are added to meals during PLZ treatment. PLZ is a tablet and therefore easy-to-use, as compared to high-protein/energy beverages that have often been used for PU treatment. Its reasonable cost is also likely to be a merit. Thus, PLZ can be a novel therapeutic option for PUs as their oral treatment. Our findings warrant randomized controlled trials for evaluating the efficacy and safety of PLZ in PU treatment. 　There is no doubt that Zn plays a crucial role in wound healing, but whether oral Zn exerts a therapeutic benefit remained unclear from our study as well as other past studies. Future study designs desirable to verify this question are to set an up to 8-week follow-up in comparisons between the effects of PLZ and CAR or between those of an inorganic Zn salt and untreated control. One more intriguing challenge is to elucidate whether Zn is involved in the mechanism of action of CAR in PU healing.


References

[1] National Pressure Ulcer Advisory Panel and European Pressure Ulcer Advisory Panel: Prevention and treatment of pressure ulcers: clinical practice guideline. National Pressure Ulcer Advisory Panel, Washington DC, 2009.

[2] Jaul E: Assessment and management of pressure ulcers in the elderly: current strategies. Drugs Aging 27: 311-325, 2010.

[3] Dorner B, Posthauer ME, Thomas D: The role of nutrition in pressure ulcer prevention and treatment:

National Pressure Ulcer Advisory Panel white paper. Adv Skin Wound Care 22: 212-221, 2009.

[4] Sanada H, Miyachi Y, Ohura T, Moriguchi T, Tokunaga K, Shido K, Nakagami G: The Japanese pressure ulcer surveillance study: a retrospective cohort study to determine prevalence of pressure ulcers in Japanese hospitals. WOUNDS 20: 176-182, 2008.

[5] Gunningberg L: EPUAP pressure ulcer prevalence survey in Sweden: a two-year follow-up of quality indicators. J Wound Ostomy Continence Nurs 33: 258-266, 2006.


Figure 4. Changes in lesions before and after PLZ treatment (trial-part 1 through -part 2) in two patients. The ruler indicates lesion areas in centimeters. PLZ, polaprezinc.

[6] Langer G, Fink A: Nutritional interventions for preventing and treating pressure ulcers. Cochrane Database Syst Rev 6: Cd003216, 2014.

[7] Sakae K, Agata T, Kamide R, Yanagisawa H: Effects of L-carnosine and its zinc complex (Polaprezinc) on pressure ulcer healing. Nutr Clin Pract 28: 609-616, 2013.

[8] Sakae K, Yanagisawa H: Oral treatment of pressure ulcers with polaprezinc (zinc L-carnosine complex): 8-week open-label trial. Biol Trace Elem Res 158: 280-288, 2014.

[9] Yanagisawa H: Zinc deficiency and clinical practice--validity of zinc preparations. Yakugaku Zasshi 128: 333-339, 2008.

[10] Vallee BL, Falchuk KH: The biochemical basis of zinc physiology. Physiol Rev 73: 79-118, 1993.

[11] Lansdown AB, Mirastschijski U, Stubbs N, Scanlon E, Agren MS: Zinc in wound healing: theoretical, experimental, and clinical aspects. Wound Repair Regen 15: 2-16, 2007.

[12] Rink L, Gabriel P: Zinc and the immune system. Proc Nutr Soc 59: 541-552, 2000.

[13] Wilkinson EA: Oral zinc for arterial and venous leg ulcers. Cochrane Database Syst Rev 8: Cd001273, 2012.

[14] Yanagisawa H, Miyakoshi Y, Kobayashi K, Sakae K, Kawasaki I, Suzuki Y, Tamura J: Long-term intake of a high zinc diet causes iron deficiency anemia accompanied by reticulocytosis and extra-medullary erythropoiesis. Toxicol Lett 191: 15-19, 2009.

[15] Hipkiss AR: Carnosine and its possible roles in nutrition and health. Adv Food Nutr Res 57: 87-154, 2009.

[16] Corona C, Frazzini V, Silvestri E, Lattanzio R, La Sorda R, Piantelli M, Canzoniero LM, Ciavardelli D, Rizzarelli E, Sensi SL: Effects of dietary supplementation of carnosine on mitochondrial dysfunction, amyloid pathology, and cognitive deficits in 3xTg-AD mice. PLoS One 6: e17971, 2011.

[ 1 7 ] B o l d y r e v A , F e d o r o v a T, S t e p a n o v a M , Dobrotvorskaya I, Kozlova E, Boldanova N, Bagyeva G, Ivanova-Smolenskaya I, Illarioshkin S: Carnosine [corrected] increases efficiency of DOPA therapy of Parkinson's disease: a pilot study. Rejuvenation Res 11: 821-827, 2008.

[18] Bae ON, Serfozo K, Baek SH, Lee KY, Dorrance A, Rumbeiha W, Fitzgerald SD, Farooq MU, Naravelta

B, Bhatt A, Majid A: Safety and efficacy evaluation of carnosine, an endogenous neuroprotective agent for ischemic stroke. Stroke 44: 205-212, 2013.

[19] Kamei J, Ohsawa M, Miyata S, Tanaka S: Preventive effect of L-carnosine on changes in the thermal nociceptive threshold in streptozotocin-induced diabetic mice. Eur J Pharmacol 600: 83-86, 2008.

[20] Sugiyama T, Tanaka H, Kawai S: Improvement of periarticular osteoporosis in postmenopausal women with rheumatoid arthritis by beta-alanyl-L-histidinato zinc: a pilot study. J Bone Miner Metab 18: 335-338, 2000.

[21] Babizhayev MA: Rejuvenation of visual functions in older adult drivers and drivers with cataract during a short-term administration of N-acetylcarnosine lubricant eye drops. Rejuvenation Res 7: 186-198, 2004.

[22] Tanaka M, Shigihara Y, Fujii H, Hirayama Y, Watanabe Y :Effect of CBEX-Dr-containing drink on physical fatigue in healthy volunteers (in Japanese). Jpn Pharmacol Ther 36: 199-212, 2008.

[23] Yamano E, Tanaka M, Ishii A, Tsuruoka N, Abe K, Watanabe Y: Effects of chicken essence on recovery from mental fatigue in healthy males. Med Sci Monit 19: 540-547, 2013.

[24] Roberts PR, Black KW, Santamauro JT, Zaloga GP: Dietary peptides improve wound healing following surgery. Nutrition 14: 266-269, 1998.

[25] Holliday R, McFarland GA: A role for carnosine in cellular maintenance. Biochemistry (Mosc) 65: 843-848, 2000.

[26] Takahashi S, Nakashima Y, Toda K: Carnosine facilitates nitric oxide production in endothelial f-2 cells. Biol Pharm Bull 32: 1836-1839, 2009.

[27] Schafer M, Werner S: Oxidative stress in normal and impaired wound repair. Pharmacol Res 58: 165-171, 2008.

[28] European Food Safety Authority Panel on Dietetic Products, Nutrition and Allergies (NDA): Scientific Opinion on the substantiation of health claims related to L-carnosine and increase in muscle power (ID 1824), increase in endurance capacity (ID 1824), “skin” (ID 1825) and maintenance of normal cardiac function (ID 1826) pursuant to Article 13(1) of Regulation (EC) NO 1924/2006. EFSA J 9: 2038, 2011.

[29] Matsukura T, Takahashi T, Nishimura Y, Ohtani T, Sawada M, Shibata K: Characterization of crystalline


L-carnosine Zn(II) complex (Z-103), a novel anti-gastric ulcer agent: tautomeric change of imidazole moiety upon complexation. Chem Pharm Bull (Tokyo) 38: 3140-3146, 1990.

[30] Seiki M, Aita H, Ueki S, Yoneta T, Takemasa T, Hori Y, Morita H, Chaki K, Tagashira E: Effect of Z-103 on wound healing by dermal incision in guinea pigs (in Japanese). Nihon Yakurigaku Zasshi 100: 165-172, 1992.

[31] DiSilvestro RA: Discussion of the scientific and clinical documentation providing a basis for the safety of zinc carnosine. 2002. Available at the U. S. Food and Drug Administration website. Accessed 23 Sep 2014.

[32] Nakao H, Yamazaki M, Tsuboi R, Ogawa H: Mixture of sugar and povidone--iodine stimulates wound healing by activating keratinocytes and fibroblast functions. Arch Dermatol Res 298: 175-182, 2006.

[33] Barnea Y, Weiss J, Gur E: A review of the applications of the hydrofiber dressing with silver (Aquacel Ag) in wound care. Ther Clin Risk Manag 6: 21-27, 2010.

[34] National Pressure Ulcer Advisory Panel (NPUAP): PUSH tool 3.0. 1998. Available at the NPUAP website. Accessed 23 Sep 2014.

[35] Bergstrom N, Braden BJ, Laguzza A, Holman V: The Braden Scale for Predicting Pressure Sore Risk. Nurs Res 36: 205-210, 1987.

[36] Ministry of education, culture, sports, science and technology: Standard Tables of Food Composition in Japan-2010. 2010.

[37] Schultz GS, Sibbald RG, Falanga V, Ayello EA, Dowsett C, Harding K, Romanelli M, Stacey MC, Teot L, Vanscheidt W: Wound bed preparation: a systematic approach to wound management. Wound Repair Regen 11 Suppl 1: S1-28, 2003.

[38] Brewer RD Jr., Mihaldzic N, Dietz A: The effect of oral zinc sulfate on the healing of decubitus ulcers in spinal cord injured patients. Proc Annu Clin Spinal Cord Inj Conf 16: 70-72, 1967.

[39] Norris JR, Reynolds RE: The effect of oral zinc sulfate therapy on decubitus ulcers. J Am Geriatr Soc 19: 793-797, 1971.

[40] Tomita H, Tanaka M, Ikui A: Clinical standard value for diagnosis of zinc deficiency by the serum zinc value on the basis of evidence (in Japanese). Biomed Res Trace Elem 18: 54-62, 2007.

[41] Japan Society for Biomedical Research on Trace Elements: The lower cut-off of serum zinc level in healthy persons (in Japanese). Biomed Res Trace Elem 21: 182, 2010.

[42] National Research Council: Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. The National Academies Press, Washington DC, 2001.

[43] Matsukura T, Tanaka H: Applicability of zinc complex of L-carnosine for medical use. Biochemistry (Mosc) 65: 817-823, 2000.

[44] Doley J: Nutrition management of pressure ulcers. Nutr Clin Pract 25: 50-60, 2010.

[45] O'Dowd A, O'Dowd JJ, Miller DJ: The dipeptide carnosine constricts rabbit saphenous vein as a zinc complex apparently via a serotonergic receptor. J Physiol 495 (Pt 2): 535-543, 1996.


review article - j-stage

Documents