Pharmacodynamic Principles - 2 Flashcards
Action of one drug is facilitated or increased by use of another drug
Synergism
Synergism can be which?
1- additive.
2- Supra-additive / potentiation
The effect of two drugs is in the same direction and adds up
Additive synergism
What are the advantages of additive synergism?
1- side effects of the combination may not add up.
2- combination is better tolerated than higher dose of one drug.
Give 2 examples of additive synergism?
1- aspirin + paracetamol.
2- glibenclamide + metformin
Effects of the combination is greater than the individual effect of the drugs?
Supra-additive synergism.
When does Supra-additive synergism occur?
When one drug is inactive, but enhances the effect of the other.
Give 2 examples of Supra-additive synergism?
1- levodopa + carbidopa.
2- acetylcholine + physostigmine.
One drug decreases or abolishes the action of another drug
Antagonism
List the 4 types of antagonism?
1- physical antagonism.
2- chemical antagonism.
3- physiological / functional antagonism.
4- receptor antagonism.
Give an example of physical antagonism?
Charcoal in alkaloid poisoning.
Give an example of Chemical antagonism?
Chelating agents complex toxic metals.
Give an example of physiological/ functional antagonism?
Histamine and adrenaline on bronchial wall
Give an example of receptor antagonism?
Acetylcholine and atropine on M receptor.
One drug blocks the receptor action of the other - it is selective in nature
Receptor antagonism
List the 3 types of receptor antagonism?
1- competitive antagonism.
2- non - competitive antagonism.
3- non - equilibrium antagonism.
Extent of shift in competitive antagonism depends on what?
Concentration of the antagonist.
List the 10 factors that affect drug action?
1- body size.
2- age.
3- sex.
4- ethnicity.
5- genetics.
6- routes of drug administration.
7- environmental factors and Time of administration
8- physiological factors.
9- pathological states.
10- other drugs.
Which factors affecting drug action influences the concentration of the drug attained at the site of action?
Body size.
How do we calculate individual dose using BW?
Individual dose = BW(kg)/70 x average adult dose
How do we calculate individual dose using BSA?
Individual dose = BSA(m2)/1.7 x average adult dose
Individual dose using BSA is used for which type of drugs?
Anti cancer drugs
The dose of a drug for children is often calculated from the _____ dose
Adult
What is young’s formula for calculating children’s dose?
Child’s dose= age/(age+12) x adult dose
What is dilling’s formula for calculating children’s dose?
Child’s dose = age/20 x adult dose
Infants and children have important _______ differences from adults
Physiological
In children which type of absorption is efficient?
Rectal absorption
Which drug is given for febrile convulsions in children?
Diazepam PR
Drugs are easily absorbed from ____ in children?
Thin skin
The BBB is more permeable is which age group?
Children
Risk of _____ in neonates following displacement of _____ from protein-binding sites by which vitamin and drugs?
Risk of Kernicterus in neonates following displacement of bilirubin from protein-binding sites by vitamin K, sulphonamides, and indomethacin.
Drugs metabolizing enzymes are immature at ____?
Birth
Inadequate metabolism of which drug causes “grey baby syndrome”?
Chloramphenicol
Kidney function is immature in which age group?
Neonates
Adult kidney function values are reached in infants after _____ of age?
5 months.
Which 3 drugs cause immature kidney function in neonates?
1- aminoglycosides.
2- penicillins.
3- diuretics.
List the 3 adverse effects that children are susceptible to?
1- suppression of growth.
2- early fusion of epiphysis > stunting of stature.
3- discoloring and deformation of teeth.
Which drugs cause suppression of growth in children?
Corticosteroids
Which drugs promote early fusion of epiphysis > stunting of stature in children?
Androgens
Which drugs get deposited in growing teeth and discolor/deform them in children?
Tetracyclines
Which dosage forms are difficult to administer in children?
1- solid dosage forms.
2- metered dose inhalers.
Oral drugs can be absorbed slowly in which age group?
Elderly
Why are drugs absorbed slowly in elderly patients?
Because of reduced blood flow and motility.
Body fat increases in which age group?
Elderly
Increased body fat in elderly acts as what?
Drug reservoir
In elderly patients what happens to total body water levels?
Decreases
What happens to water soluble drugs’s volume of distribution in elderly patients?
Decreases
In elderly patients metabolism decreases with decline in which organ’s function?
Decline in Hepatic function and liver blood flow
In elderly, drugs eliminated via first pass metabolism attain _____ concentrations in blood (____ the dose)
Higher concentrations.
Lower the dose.
Renal blood flow, glomerular filtration and tubular secretion _____ with age.
Decline
In elderly patients, there is eisk of adverse effects with drugs which are eliminated via which organ?
Kidneys
_______ dose of drugs with narrow therapeutic range, in elderly?
Decrease
Give examples of drugs with narrow therapeutic ranges which doses should be decreased in elderly patients?
Aminoglycosides, digoxin.
In elderly, drugs that act on CNS, produce which type of response?
Exaggerated
Sedatives and hypnotics have greater ______ effect, in elderly
Hangover
In elderly, sedatives and hypnotics can have which effect (other than the hangover effect)?
They can depress respiration
Response to drugs acting on ___ receptors _____ with age.
Beta receptors.
Decrease.
Response to drugs acting on beta receptors decrease with age due to what?
Reduced number of receptors.
Due to prostatism in elderly males, even mild _______ activity of drugs can worsen _____ ______ ______
Anticholinergic.
Bladder voiding difficulty.
The incidence of adverse drug reactions increase after ___ years of age.
65
List the 3 factors that increase the incidence of side effects with age?
1- increasing number of drugs that elderly need.
2- poor compliance.
3- bodily changes with aging.
We should assume that new symptoms to be adverse drug effects in which age group?
Elderly
Which group of drugs interfere with sexual function in males but not in females?
Antihypertensives
Give examples of antihypertensive drugs that interfere with sexual function in males but not in females?
Clondine, methyldopa, beta-blockers, diuretics.
Gynecomastia in males is a side effect of which drugs?
Ketoconazole, metoclopramide, cimetidine.
Androgens are unacceptable to____ (men, women).
And estrogens are unacceptable to ______ (men, women)?
Androgens are unacceptable to women.
Estrogens are unacceptable to men.
In women consideration must be given to which factors?
1- menstruation.
2- pregnancy.
3- lactation.
Does reduced GIT motility during pregnancy has an effect on oral absorption?
It has no major effect on oral absorption.
During pregnancy what happens to total body water?
Increases.
What happens to the volume of distribution in pregnancy?
Increases
In pregnancy, Plasma ____ level falls.
And ___ ____ _______ increases?
Plasma albumin decreases.
Alpha 1 acid glycoprotein increases.
During pregnancy, The unbound fraction of ______ (acidic, basic) drugs increases, but that of _____ (acidic, basic) drugs decreases.
Acidic drugs increase.
Basic drugs decrease.
Hepatic microsomal enzymes undergo what in pregnancy?
Induction.
During pregnancy, renal blood flow _____ and there is _____ loss of renal excreted drugs.
Doubles.
More loss.
Give an example of a renal excreted drug?
Penicillin.
List the 5 categories of drugs according to their effect on fetus during pregnancy, and what does it mean?
1- A: no risk.
2- B: no evidence of risk in humans.
3- C: risk cannot be ruled out.
4- D: benefit may outweigh potential risk.
5- X: contraindicated.
Shortening of bowel following gut surgery, can cause which effect of absorption?
Malabsorption.
Give examples of drugs that get malasbsorped after bowel following gut surgery?
Iron, fat soluble vitamins, vit B12.
Delayed gastric emptying during migraine ______ drug absorption.
Decreases.
Low cardiac output ______ absorption from which routes?
Decrease.
IM and SC routes
Which disease increases free (unbound) fraction of the drug?
Hypoalbuminemia
List causes for hypoalbuminemia?
Burns, malnutrition, sepsis, renal and hepatic diseases.
Hepatic diseases _____ metabolism of drugs= ____ concentration in blood.
Reduces.
High.
Drug metabolism _____ in hyperthyroidism. And _____ in hypothyroidism.
Increases.
Decreases.
Renal disease _____ elimination of drufs via kidneys. So, they can attain ____ levels.
Decreases.
Toxic.
Asthmatic attacks can be precipitated by which group of drugs?
Beta blockers.
MI predisposes to cardiac arrhythmias with which drug?
Digitalis.
Brisk diuresis can precipitate mental changes in patients with impending of which disease?
Hepatic encephalopathy.
Which group of drugs are less effective as antihypertensive in afro-Caribbean?
Beta-blockers.
Indians tolerate which drug better than whites?
Thiacetazone.
Atypical pesudocholinesterase results in what?
Prolonged succinylcholine apnea.
G-6PD deficiency causes what with primaquine and other oxidizing drugs?
Hemolysis.
Which drugs should we not give to people with G-6PD?
1- primaquine.
2- dapsone.
3- cotrimoxazole.
4- nalidixic acid.
5- methyldopa.
6- sulfasalazine.
7- nitrofurantoin.
8- sulfonamides.
Which route of administration produces more rapid and more predictable drug action?
Parenteral
Give an example of a drug that may have different uses through different routes?
Magnesium sulfate.
Orally: causes purgation (diarrhea).
Applied on sprained joints: decreases swelling.
Intravenously: CNS depression and hypotension.
List 4 environmental factors that induce drug metabolism?
1- insecticides.
2- carcinogens.
3- tobacco smoke.
4- consumption of charcoal broiled meat.
Give an example of 2 drugs that should be given at night?
1- hypnotics.
2- cholesterol.
An inert substance which is given in the grab of a medicine?
Placebo
Individual which are more suggestible and easily respond to a placebo are called what?
Placebo reactors.
Placebo effect largely depends on what?
Physician- patient relationship.
What is the opposite of placebo?
Nocebo.
