NPM Flashcards
Enzyme inducers
Example:
Phenytoin,
phenobarbital
- enhance the (production of) liver enzymes which
break down drugs - faster rate of drug breakdown
- larger dose of affected drug needed to get the same
clinical effect
Enzyme Inhibitors
Example :
Clarithromycin
omeprazole
* inhibit the enzymes which break down drugs
* decreased rate of drug breakdown
* smaller dose of affected drug needed to produce the
same clinical effect
CYP3A4
Simvastatin (substrate)
Inhibitor (Clarithromycin)
EQUALS:
Rhabdomylysis
CYP3A4
Birthcontrol (Substrate)
Inducer (Carbamazepine)
EQUALS:
Undesired Pregnancy
Factors affecting drug excretion
- Age
- Disease (CKD, atherosclerosis)
- Physicochemical properties of drug
- pH of urine
- Protein binding
- Drug interactions (NSAIDs, Ciclosporin)
Drugs excreted largely unchanged
Percentage 100-75%
Furosemide (frusemide), gentamicin,
methotrexate, atenolol, digoxin
75-50% Benzylpenicillin, oxytetracycline,
trimethoprim
drug examples Receptors
Morphine Agionist Mu
Naloxone Antagionist
Ion channels
drug example
Amlodipine Antagionist
Blocks CCB
Enzyme
drug examples
Ramipril/ibuprofen
Transporter
drug examples
sertraline SSRI
Blocks the reuptake of seritonin
Affinity
measure of the tightness with which a drug binds to
the receptor
Selectivity
specific affinity for certain receptors (vs. others)
Drug efficacy
the maximum effect the drug will produce on its target
site, e.g. blocking pathway; this is not always related to the
disease treatment efficacy or therapeutic value
Potency
the amount/concentration of drug needed to produce a
given effect; the less concentration required to achieve an
effect the more potent the drug is.
what beta-adrenergic receptors
sub-types are known and where
they are located in the body
B1B2B3
what is drug tolerance
Reduction in body’s response to medication
PD - Changes the ability of a drug to exert its effect
PK - Most common the body breaks the drug down more quickly
What is drug interaction?
An interaction occurs when the effect of one drug is
affected by the presence of another drug(s), food,
drink, herbal remedies or some environmental
substances
ADR PK: Distribution
After absorption drugs are then moved and distributed
to its site of action(s). During this process presence of
other drugs may interfere with its distribution and
mainly affect its binding to plasma proteins e.g. albumin.
This type of interaction is more significant with drugs that
highly protein bound and have a narrow therapeutic
index.
* Phenytoin and valproic acid
* Warfarin and aspirin
ADR PK: Absorption
Absorptions of one drug may be reduced or enhanced by
presence of another drug/food/drinks/herbal.
* Paracetamol and caffeine
* Doxycycline and Iron supplements
* Food and flucloxacillin
* Fentanyl patches and heat
ADR PK: Metabolism
- One of the most important mechanism where clinically
relevant interactions occur. - Drug metabolism is via liver enzymes, cytochrome P450,
CYP. - The metabolism of one drug is enhanced or reduced by
another drug if the production or action of the enzymes
involved are affected.