Pharma W13 Flashcards
Define therapeutic effect
A drug/chemical that affects the function of the human body.
Only non-ionised drugs can cross the cell membrane.
What types of acids/bases are they? And what are they bound to usually to cross?
Weak acids and bases
Bound to plasma proteins, like albumin
What is pKa of drugs?
pH at which half of the drug is ionised. Behaviour at specific pH
What is involved in the metabolism of drugs?
Primarily in the liver.
Phase 1 = cyp450, lipid soluble
Phase 2 = conjugation reaction to become more water soluble and more inactive
What has an effect on excretion of drugs?
Blood contains bound drug metabolites
Non-ionised drug diffuses out of tubule.
pH of urine - weak acids leave better
If not well hydrated, drug can get reabsorbed.
What is the difference between first order elimination and zero order?
First order = more enzyme molecules than drug - to break down molecules, half-life
Zero order = more drug molecules than enzyme, alcohol is zero order
What are factors that affect drug action of absorbance?
GI disease, cardiac disease- blood flow (beta blockers), diet- green tea, pregnancy- gastric emptying
Factors that affect drug action in distribution?
Body fluid issues- oedema, dehydration, plasma protein concentration (less plasma, more drug around because not bound to plasma protein).
Metabolism and excretion are factors that affect drug action. List some examples.
Cardiovascular disease
Liver disease
Kidney disease
Diet foods- grapefruit juice and antihypertensives/ anti coagulants- it makes you take up more of the drug than is intended.
Give an example of the extension effects of drug use
Drugs like warfarin- anti-coagulant- causes excessive bleeding
Insulin - lower BG- hypoglycaemia.
Give an example of a drug-drug interaction
Administration of one drug can alter the action of another.
Beta blockers (adrenoceptor antagonists) diminish affect of bronchodilators, salbutamol.
OR
NSAIDS reduce effect of ACE inhibitors- raise blood pressure.
If patient is on anti-anxiety medication, what drug interaction do you need to watch out for?
When giving them a sedative, or local- slows down breathing.
How does drugs effect on gut motility affect absorption?
Inhibition of gut motility = increases absorption of drug
Increase of gut motility = decreases absorption of drug
How does competition of drug binding to plasma proteins affect distribution of drug?
Drugs that displace = decrease plasma proteins, increases the amount of free drugs around.
Multiple drugs can use the same isoform- therefore competing for metabolism.
Give an example and the effect it can have on metabolism
Cytochrome p450 isoform can slow metabolism of one drug, make the other higher = toxic effect. I.e. St John’s Wort increases CYP450 activity, which reduces its effectiveness.
