General Flashcards
Drugs with low therapeutic index i.e. narrow margin of safety
Warfarin Gentamycin Lithium Phenytoin Digoxin Theophylline
Monitoring of their serum levels is required
Phases of clinical trials
Phase I Safety
Phase II Efficacy(therapeutic exploratory study)
Phase III Approval (therapeutic conformation trial)
Phase IV Long term(post marketing survelliance)
“SEAL”
Orphan drugs are
Used to diagnose,treat and prevent rare diseases.
Eg. Digoxin antibody (digoxin poisoning)
Fomepizole(methyl alc poisoning)
Factors determining selection of drug for administration
Characteristics of the drug Emergency/routine use Condition(unconscious vomiting diarrhoea) Age Associated diseases Choice of patient/doctor
Routes of drug administration
Local
Systemic(enteral/parenteral)
Special drug delivery systems
Ocusert(lower eyelid) Progestasert(intrauterine contraceptive) Liposomes(phospholipid vesicles) Antibodies(immunoglobulins) Drug eluting stents Computerized miniature pump(insulin)
Ocusert can be used for
Pilocarpine(glaucoma)
Liposomes are used for
Amphotericin B (fungal infection)
Drugs that is given by eluting stents is
Paclitaxel
Mucosal membranes for topical drug administration
Oral cavity (clotrimazole) Git (neomycin) Enema(soap water enema) Eye,ear (gentamicin) Bronchial inhalation (salbutamol) Vaginal (candidiasis) Urethra (lignocaine...anti-arrhythmic) Skin (clotrinazole)
Local route of drug administration
Topical Intra arterial(triamcinolone in joint spaces in rheumatoid arthritis)
Advantages of oral drug administration
Safer Cheaper Painless Self admintered For repeated /prolonged use
Disadvantages of oral route of drug administration
Irritants Unabsorbables Digestive juices High first-pass Unconscious Unreliable Vomiting and diarrhoea Not for emergency
Advantages of sublingual
Quick
Terminable
No first-pass
Self administered
Disadvantages of sublingual drug administration
Irritants
Lipd insoluble
Bad taste
Drug as suppository
Indomethacin (arthritis)
Drug for enema
Diazepam (status epilepticus-children)
Disadvantages of parenteral route of drug administration
Aseptic conditions Sterile Expensive Painful No self administered Local tissue injury
Drug by intradermal route
BCG
Drug senstivity test
Subcutaneous injection
Adrenaline
Insulin
Depot preparations
Norplant (contraceptive)
Injectable routes of drug administration
Intradermal Subcutaneous Intravenous Intra-arterial Intramuscular Intra-articular
Advantages of intravenous drug administration
Bioavailability Quick onset Larger volume can be given Irritatants Hypertonics Constant plasma volume maintained
Disadvantages of iv
Local irritation (phlebitis) No self administration Aseptic needed Extravasation(necrosis, sequestration) No depot
Intrathecal injections
Lignocaine(anaesthesia)(anti-arrhythmic)
Amphotericin B
Given in subarachnoid space
Transdermal drugs
Scopolamine (motion sickness) Nitroglycerin (angina) Estrogen (hormone replacement) Clonidine (hypertension) Fentanyl (pain) Nicotine (de addiction)
Advantages of tansdermal
Self administration Better compliance Duration prolonged Side effects less Constant concentration no First-pass
Disadvantages of transdernmal
Expensive
Dermatitis
Itching
Fall off
Bioavailbilty
Fraction of drug reaching systemic circulation
Bioequavalents and bioinequivalents
2 formulation of same drug produce equal bioavailability
Formulation differ- bioinequivalents
First pass metabolism
Drug pass via Gut wall Portal vein Liver (metabolism) Systemic circulation
Factors affecting drug absorption
Drug property Route Ph- ionisation Food Other drugs Absorbing surface area Git problems
Factors affecting bioavailability
First-pass
Hepatic diseases
Interohepatic circulation
What is Apparent volume of distribution (aVd)
Hypothetical volume of body fluid in which drug is uniformly distributed(concentration equal to plasma)
Total amount of drug in body/conc. Of drug in plasma
Redistribution of drug is defined as
Lipid soluble drugs that crosses blood brain barrier (BBB)
Barbiturates
Diazepam
Amphetamine
Increased penetration in meningitis and encephalitis
Drugs that cross placental barrier
Anaesthetics
Morphine
Corticosteroid
What is biotransformation
Chemical alterations in drug Eg. Codiene- morphine Diazepam- oxazepam Levodopa- Dopamine (prodrug) Prednisone- prednisolone
Phenobarbitone- hydroxyphenobarbitone
Types of ADR
A augmented B bizzare C chronic D delayed E end of therapy (withdrawal) F failure of therapy
Science and activities related to detection, assessment, understanding and prevention of ADR
Pharmacovigilance
Idiosyncrasy
Genetically determined abnormal reactivity to a chemical.
Cardinal features of drug allergies
Severity poorly corelated to dose Similar to allergic. Diseases Prior sensitization \+ Dechallenge and rechallenge Unrelated to drug pharmacodynamics
