elderlypreg drugs pracs ug
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Reasons for considering drug therapy in elderly as a specific group
Physiological and pharmacological changes in elderly Elderly consume good portion of health expenditure ADRs more common in elderly Polypharmacy more (multiple diseases): drug interactions
more Increased error in taking medicines Frailty, poor appetite and nutrition, forgetfulness,visual
impairment, lack of self care, lack of supervision, financial problems
Physiological changes Changes in body composition : lean body mass, body size, body water,bone density, albumin AND Increased
body fat & α1 acid glycoprotein
GIT : gastric acidity,Delayed gastric emptying time, in GIT & liver blood flow.
RS : in total vital capacity & bronchial ciliary function CVS : in baroreceptor activity,COP & myocardial sensitivity to
beta agonists/antagonists Renal : GFR,renal blood flow& tubular secretion NS : Cognition defects,Reduction in central NTs, Impaired
cerebral autoregulation
Physiological changes contd…. GU : Prostate hypertrophy in males,Vaginal
atrophy and menopause in females Endocrine : Increased incidence of DM & thyroid
disorders Musculoskeletal : Reduction in muscle mass ,Power &
Joint flexibility.
Pharmaceutical factors Difficult to swallow Tab , Capsules Easy to swallow syrups, suspensions Medicines should be in easily opened containers Labelling in large print , clear
Pharmacokinetic factors Absorption : Drugs absorption from intestine is slow
( decreased motility & decreased blood flow)
Distr ibution : Increase in free acidic drugs (decreased plasma albumin & decrease in free basic drugs (increased α1 acid glycoprotein). Lipid soluble drugs accumulate more (body fat more in elderly)
Metabolism : Enzyme activity in liver decreasedoral bioavailability of drugs with high first pass metabolism increased.
Excretion : Excretion of drugs decreased (renal function reduction). Dose of drugs excreted through kidney has to be reduced.
Excretion Cockcroft-Gault formula Creatinine clearance ml/mt = (140-age)× wt(Kg) 72 X S.Creatinine Females – multiplied by 0.85
ADRs peculiar to elderly
Treatment of HTN often results in postural hypotension, falls, injury (cerebral autoregulation deficient, peripheral autonomic responses sluggish in response to hypotension)
Diuretics lead to hypokalemia & can lead to digitalis toxicity if co-administered.
Brisk diuresis can lead to A/c urinary retension in old men with BPH
Precipitation of gout with diuretics Confusion precipitated with anticholinergis/antihistaminics Use of antipsychotics can lead to parkinsonism for which elderly
are more prone Greater incidence of peptic ulcer with NSAIDs(due to decreased
clearance of NSAIDs)
CNS drugsSedative hypnotics
Prolongation of half life of benzodiazepines, barbiturates (due to decreased metabolism-excretion)
Half l i fe of Lorazepam,Oxazepam less affected. Hence preferred over Diazepam, barbiturates
Side effects like ataxia, motor incoordination to be looked for while prescribing these drugs.
CNS drugsOpioid analgesics
Elderly sensitive to respiratory depression due to decreased respiratory reserve.
Morphine, codeine use justified in chronic painful conditions but with caution
CNS drugsAntipsychotics
Classical antipsychotics associated with EPS & can worsen Parkinsonism if present.Their Anticholinergic effects can worsen BPH, AD if present. Alpha blocking property (CPZ) can cause orthostatic hypotension Atypical antipsychotics (eg :Olanzapine,Aripiprazole) preferred.
Antidepressants Avoid TCA with anticholinergic S/E ( Preferred – Nortriptline, Desipramine)Safe - SSRI
CNS drugs
AntimaniaLi excreted by kidney. Doses in elderly should be adjusted depending on kidney function.Thiazides reduce Li clearance. Li doses should be reduced further in presence of thiazides.
Carbamazepine, Valproic acid preferred over Li
CVSAntihypertensives
Thiazides are 1st step in Rx of HTN. Low doses are used because of higher incidence of arrhythmias, DM, gout in elderly. (hypokalemia, hyperglycemia, hyperuricemia are S/E of thiazides)CCBs are safe & useful if angina is coexistentB blockers less useful unless heart failure present. Can be dangerous in COPD patients. Can cause bradycardia in elderly.ACEI less useful unless DM/heart failure presentCheck for orthostatic hypotension in all elderly receiving antihypertensives
CVSCardiac glycosides
Digoxin - half life increased as Clearance decreased (decreased renal function). Hence digoxin dose to be adjusted according to kidney function.
Elderly more sensitive to digoxin induced arrhythmias & Extra cardiac side effects
cvs
Antiarrhytmics Avoid Disopyramide due to its anticholinergic effects & negative inotropic effects.Reduce dose of Qunidine, Lignocaine (as their excretion through kidney reduced)
Antidiabetics
Chlorpropamide, Glibenclamide not used –hypoglcemia highGlipizide, Gliclazide – used Metformin Nateglinide
Antibiotics
Penicillin, Cephalosporin,Nitrofurantoin, FQs, Aminoglycosides --- dose adjusted
Tobramycin Ceftriaxone, Cefperazone
Principles of treatment in elderly Careful drug history Prescribe only for specific & rational indication Define the goal of therapy Start with lowest dose & titrate Avoid Polypharmacy If possible-One drug for two indications Avoid symptomatic treatment without specific diagnosis Choose the right dosage forms Financial problems – prescribe cheaper alternatives rule out non compliance/errors in taking drugs Watch for ADRs & drug interactions
Introduction Most drugs administered to mother can cause placenta and
affect the fetus Teratogenic affects are the important consideration while
prescribing during pregnancy History : Thalidomide disaster
USFDA drug categories in pregnancy
A Adequate studies in pregnant women, show no risk to fetus
Inj MgSo4, thyroxine, fol ic acid
B Adequate human studies lacking but animal studies show no risk to fetus OR adequate studies in pregnant women show no risk to fetus but animal studies have shown an adverse effect on fetus
Penicillin, Amox, erythromycin, paracetamol, lignocaine, cefaclor
C No adequate studies in pregnant women, animal studies are lacking/show adverse effect on fetus, but potential benefit may warrant use of the drug in pregnant woman despite the potential risk (RISK CAN’T BE RULED OUT)
Most drugs (morphine, steroids, adrenaline, bupivacaine, atropine)
D Evidence of fetal risk, but potential benefit may be acceptable despite potential risk (POSITIVE EVIDENCE OF RISK)
Aspirin, antiepileptics
X Studies in humans/animals show fetal risks. Absolutely contraindicated
Isotretinoin, estrogens, cytotoxic drugs
Examples of teratogenic effectsThalidomide Phocomelia
Methotrexate Hydrocephalus, cleft palate
stilboestrol Vaginal adenocarcinoma in teenage offspring
Tetracycline Bone & teeth abnormalities
Warfarin CNS & skeletal defects
Phenytoin Hydantoin syndrome
Carbamazepine NTD
Valproate Spina bifida
ACEI Renal tubular dysgenesis, oligohydramnios
Lithium Fetal goitre, Ebstein’s anomaly
Isotretinoin Craniofacial, CVS defects
Principles of prescribing in pregnancy
Wherever possible, use non drug therapy Prescribe drugs only when definitively needed As far as possible, avoid medication in the first trimester of
pregnancy Use lowest effective dose for shortest period & if possible
give drug intermittently Choose drugs having best safety record over time Avoid newer drugs unless safety is clearly established Discourage patient from self medication & OTC.
Prescribing for common problems during pregnancy
Nausea, vomit ing Reassurance, high carbohydrate diet, antihistaminic-antiemetic (diphenhydramine, doxylamine)
Heartburn Avoid fatty food/alcohol/smoking. Non systemic antacids & Metoclopramide
constipation High fibre diet, plenty of oral fluids, mild laxatives like milk of magnesia, bisacodyl
Safe & unsafe drugs for various disorders in pregnancy
SAFE NOT SAFE
ANTIMICROBIAL THERAPY
B lactam antibiotics, erythromycin base, nitrofurantoin, methenamine, nystatin, miconazole
erythromycin estolate (hepatotoxicity), Aminoglycoside, TC, Chloramphenicol, Co-trimoxazole, Sulfonamides, nalidixic acid, Griseofulvin, Ketoconazole, FQs
ANTITUBERCULAR DRUGS
INH, Ethambutol Rifampicin, Streptomycin
ANTHELMINTHICS
Metronidazole (low doses), Diloxanide, Chloroquine, Quinine, Piperazine, Pyrantel
Primaquine, mefloquine, Mebendazole
ANALGESICS
Paracetamol Aspirin , other NSAIDs
ANTIHYPERTENSIVESAlpha methyl dopa, CCB, labetalol B blockers, ACEI, ARBs
HEART DISEASESimilar treatment as non pregnant with Digoxin ANTICOAGULANTHeparin warfarin ASTHMAInhaled B agonists, inhaled steroids
DIABETES MELLITUS
Diet restriction, insulin if needed OHA
THYROTOXICOSIS
Propylthiouracil> carbimazole Radioactive iodine
EPILEPSY
PB , (Phenytoin) (supplement folic acd &vit K) Valproic acid, Carbamazepine
Other CNS drugs
BZD, Barbiturates, antidepressants,opioids (best avoided near term to avoid neonatal CNS depression)
Lithium
Prescribing during lactation Most drugs administered to lactating mother detected in
breast milk(in lower conc than maternal plasma) Ideally medicines to be taken 30-60 min after nursing or 3-4
hrs before next feed to allow time for many drugs to clear from mother’s blood.
Drugs for which safety during lactation not established should be avoided/breast feeding avoided during their use.Eg : Anticancer drugs, immunomodulators
Drugs excreted in high conc in breast milk & those which can cause adverse effects in infant : Tetracyclines, INH, Sedative-hypnotics, Opioids, Lithium, radioactive iodine
Drugs which are excreted in small amounts in breast milk but can cause adverse effects in fetus: Penicillin (hypersensitivity), sulfonamides(hypersensitivity, kernicterus, hemolysis in G6PD deficient infants)
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