fundamentals of la administration
Post on 11-Jul-2015
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Definition of Pharmacology
Pharmacology is the study of the interactions that occur between our body and chemicals. Knowing
more about the action and uses of a drug.
Importance of Pharmacologyto OHT
• Knowledge of how and when the drug is administered
• Improve patient experience
• Increase the efficiency of dental procedures
• Provide clear explanation of drug to patient (only when prescribed)
• Improve infection control and prevent fatality
MEDICATIONSMedication/ Ulcer Creams/ Local Anesthesia
In what situations is medication incorporated to the job of a OHT?
Almost everyday!When taking medical history
we need to be aware of diseases that the patient might have. Especially if poses any risks during dental procedures.
MEDICATIONSMedication/ Ulcer Creams/ Local Anesthesia
In what situations is medication incorporated to the job of a OHT?
When treating patients who are at high risk of infective endocarditis, sudden bacteremia may be produced by dental manipulation within the mouth.
MEDICATIONSMedication/ Ulcer Creams/ Local Anesthesia
Who are at high risk of infective endocarditis?
Congenital Heart
Disease
Rheumatic
Heart Disease
Congenital
Heart Disease
MEDICATIONSMedication/ Ulcer Creams/ Local Anesthesia
So, when treating such patients…
To get approval from doctor Example of common medication
given is antibiotics-amoxillin. Better absorbed, following oral
administration Amoxicillin is one of the most
common antibiotics prescribed for children
ULCER CREAMS
When a patient walks in to a clinic…
1. We need to identify the cause of the ulcer
2. Consider treating it3. Prescribe ulcer cream
Medication/ Ulcer Creams/ Local Anesthesia
Medication/ Ulcer Creams/ Local Anesthesia
And now, an advertisement
ULCER CREAMSMedication/ Ulcer Creams/ Local Anesthesia
When local anesthesia is used?
Extraction of teeth Removal of Gum PolypCavity Preparation
LOCAL ANESTHESIAMedication/ Ulcer Creams/ Local Anesthesia
Medication/ Ulcer Creams/ Local Anesthesia
A live extraction in class
LOCAL ANESTHESIAMedication/ Ulcer Creams/ Local Anesthesia
• Also known as antibacterials• Organic substances either produced by micro-organisms or
synthetically manufactured• Drugs used to treat infections caused by bacteria• Inhibit growth of bacteria and other micro-organisms• Not effective against viruses
Uses of DrugsANTIBIOTICS
Antiseptics & Disinfectants
• Basic tools of cleaning and sanitizing
• Eliminate disease-causing organisms
Uses of Drugs
Haemostatics & Styptics
• Blood clotting agents• Arrest the flow of blood
(clotting)• Promote vasoconstriction
ANTISEPTICS & DISINFECTANT /
HAEMOSTATICS & STYPTICS
Pain & Pain Control
• Manage and subdue pain faced by patience
• Provide ease to operator to carry out procedure
Uses of Drugs
Vasoconstriction drugs
• Blanching of tissues• Narrows blood vessels
Pain & Pain Control / Vasoconstriction
Route of Entry
External Route
On the skinMucous
membrane of mouth
Mucous membrane of
rectum
Internal Route
Ingestion, Oral Route Injection
Inhalation
External Route
• Applied on the surface: local effects only.
• Depending on chemical structure and quantity applied
• Can be absorbed by the skin and mucous membrane
• Greatest Penetration: drugs with low molecular weight with a high water and lipid solubility
Point of Entry Examples
On the skin Creams, Lotions
On the mucous membrane of mouth
Lozenges, Gargles
On the mucous membrane of rectum
Suppositories
External Route
Internal Route
1) Ingestion or Oral Route
a. In the mouth, some drugs are readily and rapidly absorbed via the mucous membrane in the mouth
b. In the stomach and small intestine, drugs that are swallowed are absorbed through the lining mucosa
Internal Route
2) Injection
a) Intradermal – in the layers of the skinb) Subcutaneous – into the undersurface of the skinc) Intramuscular – into the deep-seated musclesd) Intravenous – into the veinse) Intraspinal – into the spinal space
Internal Route
3) Inhalation
• Drugs in the form of vapor may be inhaled into the lungs.
• Very small molecular structure and pass easily through the thin epithelium.
• Absorbed through pulmonary endothelium at alveoli to gain rapid access to the general circulation
• To carry the product and keep it stable, till it is consumed
• Transparent capsules & syrup in a transparent glass bottle is preferred a lot more
• They are not only attractive but are also more trustworthy because patients can “see” what they are consuming
• Most manufacturers are no longer hiding the medicines behind opaque covers
• Many tablets today are coated after being pressed. Some coatings are just to provide colour or a smooth finish, or to facilitate printing on the tablet
• Some tablets have coatings which is designed to hold the tablet together when it is in the stomach
• The coating is designed to hold together in acid conditions and break down in non-acid conditions and therefore release the drug in the intestines
• Example: Aspirin• An enteric coating is
there usually for a good reason and therefore such tablets or the contents of enteric coated capsules should never be crushed before being taken.
• Soft-shelled capsules, primarily used for oils and for active ingredients that are dissolved or suspended in oil
• Solutions, syrups and mixtures• Commonly used in patients that have difficulty
swallowing medicines like children and the elderly• The liquid medicine should be made such that the
dose needed will be a sensible volume such as 5ml (one teaspoon)
ACTIVITYPurpose/ Route of Entry/ Packaging/ Form of Medicine
PURPOSE ROUTE OF ENTRY
PACKAGING FORM OF MEDICINE
1. Antiseptics
2. Pain control
3. Haemostatics
and Styptics
4. Antibiotics
5. Vasoconstriction
External route
1. Skin
2. Oral Mucosa
3. Membrane of
rectum
Internal Route
1. Ingestion
2. Injection
3. Inhalation
1. Hard shelled
Capsules
2. Soft Shell
Capsules
3. Liquid
4. Coated Tablets
1. Blister
Pack
2. Bottle
3. Tube
Absorption of Drug
• Absorption is the process by which a drug passes from its site of administration into the circulation (bloodstream).
• The blood receives a drug from the site of administration and carries it to all the organs, including those on which the drug acts.
• The speed, ease, and degree of absorption are related to the route of administration.
Absorption of Drug
• The absorption rates of drugs depend on its physical and chemical properties, on the site of absorption and the solubility of drug.
Site of Absorption Rate of Absorption
In mucous membrane Rapid
In small intestine Depends on health of stomach and its activity and presence/absence of food
Subcutaneous and Intramuscular injections
Depends on water solubility of drug, dose form and blood supply at site.
Intravenous Injection Immediate
Inhalation Immediate
Distribution of Drug
• After the drug is absorbed, it is then distributed to various organs of the body.
• Influenced by how well each organ is perfused, organ size, binding of the drug to various components of blood and tissues, and permeability of tissue membranes.
• The more fat-soluble a drug is, the higher its ability to pass across the cell membrane is.
• Protein binding is an important consideration influencing drug distribution.
• Many drugs are bound to blood proteins such as serum albumin and are not available as active drugs.
Metabolism of Drug
• Metabolism occurs via two types of reactions:
• Goal: Change the active part of medications (a.k.a functional group) making them more water-soluble and more readily excreted by the kidney.
• Changing the molecular structure of drugs= water solubility= fat solubility= faster excretion of drug in the urine.
and
Metabolism of Drug: Phase I
• Phase I: reactions involve oxidation, hydrolysis, and reduction.
• Oxidation and reduction processes make a molecule's charge more positive or negative than the original drug.
• Regardless of the positivity or negativity, a charged molecule = dissolvable in water
• Take place primarily in the liver by enzymes• Oxidative metabolism may result in formation of
an active metabolite or inactive compound.
Metabolism of Drug: Phase II
• Phase II: reactions involve conjugation to form glucuronides, acetates, or sulfates, by adding glucose, acetate, or sulfate molecules, respectively.
• These reactions generally inactivate the pharmacologic activity of the drug and may make it more prone to elimination by the kidney.
Excretion of Drug
• Excretion of a drug = duration of action= toxicity.
• Drugs may be eliminated as a parent drug (unchanged) or as metabolites (changed form).
• PharmacoDYNAMICS: what the drug does to the body; this term refers to the action of the drug at the tissue-,cellular-, and molecular level.
– Specific and different for each drug
PharmacoKINETICS: what the human body does to the drug Excretion occurs primarily through the urine.
Fecal excretion is seen with drugs that are not absorbed from the intestines or have been secreted in the bile.
sweat
KIDNEY
• Most important organ for elimination of drugs and its metabolites
• Eliminated in the urine
① Passive glomerular filtration (most drugs)
② Active tubular secretion (e.g. penicillin)
③ Passive tubular secretion (e.g. salicylates)
• In the case of renal damage:
excretion of drugs; toxicity
BILE
• Usually involve orally ingested unabsorbeddrugs or metabolites excreted in the bile, that are not reabsorbed from the small intestine
• Eliminated through feces
• Examples of drugs
– Phenytoin
– Phenolphthalein
INTESTINES
• Oral and enteral medications (like purgatives) are absorbed in small intestine
• Excreted in large intestine
• Eliminated through stools
• Example:– senna
– cascara
LUNGS
• Drugs like volatile general anaesthetics, ethyl alcohol are excreted through lungs
• Most drugs excreted here are not metabolized first
• Example:– Ketamine
– propofol
SALIVA
• Drugs like iodides and metallic salts are excreted through saliva.
• Such as lead is eliminated through saliva and its deposition produces black lining of teeth.
BREAST MILK
• Breast milk is more acidic than plasma
• May produce drug toxicity in the nursing infant
• Pulmonary excretion (e.g. breathing) is important as it pertains to the elimination of anesthetic gases and vapors, as well as alcohol.
• Example: pethidine
FACTORS TO CONSIDER WHEN PRESCRIBING DRUGS
Dosage ofdrugs
Presence ofother drugs
Time of administration
Patientcompliance
Weight ofpatient
Age
Sex
Severity of the disease
Dosage of drugs• Weight of patient
Dose = Adult Dose x Weight (kg)
• Age
Age x Adult dose
70
Age + 12
• Sex
Females are given 7/8 male dose.
• Neonates-new born(calibrated dose)
• Infants-1-6 years(1/4 adults dose)• Children- 6-12 years(1/2 adult
dose)
Presence of other drugs
• Some drugs cancel each other’s effects
• Combined effect would be harmful to the patient
• Hence, consideration must be taken if patient is on other drugs
Time of administration
• Time relationship to meals could influence the actual effective therapeutic dose
• Absorption occurs more rapidly if stomach and upper portion of body are free from food
• Drug action may depreciate when medication given after a meal
• Irritant forms of medication are better tolerated if food already present in gut.
Patient compliance
• Patient does not take medication due to:
o Lack of faith in medication
o Poor understanding of illness
• Patient takes medication incorrectly
• Patient stops taking medication midway
FACTORS THAT MODIFY DRUG EFFECTS
Patient complianceOther drugs
Age & Weight
Rate of elimination
Physiological factors
Tolerence and cross-tolerence
Sex
Pathologic factors
Route of administration
Time of administration
Psychological factors
Genetic variation
0
2
4
6
8
10
8 16 24 32
1st Dose
2nd Dose
3rd Dose
No Effect
Toxic Level
Blo
od
Co
nce
ntr
atio
n
Time
Blood Concentration VS Time Curve of Repeated Dosing
Distribution+
Metabolism
HALF –LIFE/ THERAPEUTIC
LEVEL
CONCLUSION!
1. Pharmacology and it’s use
2. Route of administration
3. Packaging
4. Form of drugs
5. Absorption, Distribution, Metabolism, Excretion of Drugs
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