Case studies

Question 1

Oral drug metabolism and examples

Answer 1

susceptibly of drug to digestion in the GI tract
insulin/GH/oxytocin/ antibodies: have amide bonds, so can’t be taken orally as they will be degraded in GI
siRNA/ nucleotides: phosphodiester bonds, difficult to get into cells with phosphate, can’t be taken orally
Penicillin: low pH in stomach can degrade

Question 2

Administration of anti-psychotic drugs

Answer 2

Can be difficult to get reliable taking of tablets

inject a long-lasting drug into muscle, contains oil with an anti-psychotic

Question 3

Tubular secretion and reabsorption

Answer 3

Penicllin
Actively secreted from the blood, not filtered out
Transporter can be blocked to increase half life

Question 4

Drugs and plasma binding proteins

Answer 4

Digoxin and warfarin bins to albumin, compete for binding site which can cause issues as they both have a narrow therapeutic index

Question 5

L-DOPA

Answer 5

dopamine can’t be given orally, and not IV as it can’t cross the BBB
Give as pro-drug L-dopa, can pass through BBB and then converted into dopamine

Question 6

MAO inhibitors

Answer 6

catecholamines undergo rapid oxidation with MAO

if prevent breakdown, can reduce depression

Question 7

Selective seratonin re-uptake inhibitor

Answer 7

NA relates to alertness, dopamine to reward and 5-HT to mood

SSRI act on just 5-HT transporter to increase length of time acting on the brain