Introduction To Pharmacology Flashcards
What is pharmacy?
Handling of drugs
What is pharmacology?
Science of drugs
What is toxicology?
Deals with poisons and hazardous effects of therapeutic drugs
What is therapeutics?
Medical use of drugs
What is the typical molecular weight of a drug?
200-1000 Daltons
What are drugs?
Chemicals that bind to molecules in cells
Mimic, stimulate or block the action of endogenous molecules/processes
What are chemotherapeutic drugs?
Agents which act against infectious micro-organisms or cancer cells by exploiting biochemical differences between normal and target cells
What are some common mechanisms by which drugs work?
Enzyme blocker or activator
Ion pump blocker
Receptor modulator or blocker or agonist
Chemotherapeutic agents
What do local anaesthetics do?
Block Na+ channels
What is KD (dissociation constant)?
Concentration of drug required to occupy 50% of the receptors at equilibrium
Related to affinity
What does a low KD tell you about a drug?
High affinity
What is efficacy?
Relates to drug’s ability to activate the receptor to produce a response
OR
How well the drug activates the receptor
What is an agonist?
Ligand that binds and activates a receptor
What is an antagonist?
Ligand that binds to and does not activate a receptor
OR
Drug with affinity but no/zero efficacy
What does AR* mean?
Agonist bound to a receptor producing a response
What does AR mean?
Agonist or antagonist bound to a receptor
What is affinity?
How readily a drug binds to a receptor
What is a full agonist?
Drug with maximum possible efficacy
What is a partial agonist?
Drug with less than maximal efficacy
How does a reversible competitive antagonist affect the dose-response graph?
Parallel shift to right
Size of shift depends on concentration of antagonist
(Blocking by antagonist is surmountable by increasing agonist concentration)
How does an irreversible competitive antagonist affect the dose-response graph?
Suppressed maximal response (not surmountable)
Degree of suppression dependent on antagonist concentration
What does it mean when a drug has high potency?
Effective in small amounts
What could cause a drug to have high potency?
High affinity
High efficacy
Slow metabolic breakdown in body
What quantifies drug potency?
EC50
What is EC50?
Concentration of drug producing 50% of the maximal response
What does amoxicillin do?
Inhibit peptidoglycan synthesis
Destroy bacteria
What does metronidazole do?
Causes DNA strand breakage
Taken into non-mammalian cells and reduced to active form
What does erythromycin do?
Inhibits protein synthesis by acting on 50S ribosomal unit
What does tetracycline do?
Inhibit protein synthesis by competing with tRNA in precaryotic cells
What is pharmacodynamics?
Effect of drug on organism
What is pharmacokinetics?
Effect of organism on drug
What is a big factor affecting absorption of a drug?
Lipid solubility of a drug (must cross lipid bilayers)
What type of compound are local anaesthetics?
Weak bases
What kind of pH does inflamed tissue have?
Low pH
Why are local anaesthetics injected with sodium bicarbonate?
Increase local pH
More uncharged form of drug
Increases speed of anaesthesia onset
What does bioavailability mean?
Proportion of drug reaching circulation
What does i.m. mean?
Intramuscular
What does i.v. mean?
Intravenous
What does s.c. mean?
Subcutaneous
What are phase 1 reactions?
Catabolic
Product may be more toxic/active than parent (benzodiazepines)
What are phase 2 reactions?
Synthetic
Add chemical groups to form an inactive, more water-soluble compound
Where does the excretion of most drugs occur?
Kidneys
How do drugs enter the kidney?
Glomerular filtration
Peritubular capillary secretion
What type of drug is not easily excreted via the kidneys and why?
Lipid-soluble
Easily diffuse out of nephron
What is t(1/2)?
Half-time
Time for drug concentration in plasma to halve
Why do elderly people not need as large doses as younger people?
Drug metabolism and renal function decreases with age
Drug has higher potency
What does it mean when two drugs are pharmacodynamic?
Similar or opposite effects
What does it mean when two drugs are pharmacokinetic?
One alters the absorption/distribution/metabolism/excretion of the other
What happens if you take two drugs that are transported into the renal tubules by the same mechanism?
Mutual slowing of excretion
What can induction of hepatic enzymes cause?
Decrease the effectiveness of other drugs metabolised by these enzymes (removed faster)
What can inhibition of hepatic enzymes cause?
Increase effectiveness of other drugs metabolised by these enzymes (remain in body longer)
What does phase I of a clinical trial test for? (3)
Pharmacokinetics
Side effects
Potency
What does phase II of a clinical trial test for? (2)
Efficacy
Dosage
What does phase III of a clinical trial test for? (3)
Efficacy/comparison with current drugs
Optimal dosage
Incidence of side effects
What kind of volunteers are used in phase I of clinical trials?
Healthy
What kind of volunteers are used in phase II of clinical trials?
Patient
What kind of volunteers are used in phase III of clinical trials?
Patient
How long does a clinical trial last?
6-10 years
