IC2 PK PD Flashcards
Gastric acid suppression therapy results in reduced levels of ________
Vit B12, Ca, Fe
Gastric acid suppression therapy results in reduced absorption of which drugs?
- Itraconazole (85%)
- Ketoconazole (64-66%)
- tinib (tyrosine kinase inhibitors) e.g., erlotinib, dasatinib and nilotinib
Which drug prolong GI transit
Anticholinergics, opioids, antispasmodic
Key absorption changes in old age
- Mucosal atrophy (resulting in reduced gastric acid secretion)
- Prolonged GI transit time
- First pass metabolism in small intestine
- Thinner epidermis and dermis
- Cutaneous blood supply drops
Clarithromycin is a PGP-_____ which increases Cmax of___ by 84% and levels of the drug by 64%
inhibitor; digoxin
Phenytoin is a PGP-____ which reduces ____ ‘s oral bioavailability from 84% to 33%
inducer; dexamethasone
Key distribution changes in old age
- Total body water and lean muscle mass drop
- Fat increases
- Decrease in serum albumin, more drop if sick
- Incr alpha-1 glycoprotein
- More leaky BBB
- Lower PGP activity
Fluconazole is CYP___ inhibitor. At high dose of 200mg it is also a CYP____ inhibitor.
2C9; 3A4
Drugs metabolised by CYP2C9
SU, glipizide, tolbutamide
Key metabolism changes in old age
- Phase I metabolism lower
- Lower UGT activity
Major enzyme is Phase I and II metabolism
Phase I: CYP3A4
Phase II: UGT
Why is Phase I metabolism lower in old age
due to reduced liver mass, hepatic blood flow, and thickening of
sinusoidal endothelium
CYP inhibitors
Azole agents, clarithromycin, cimetidine
CYP inducers
phenytoin, carbamazepine, rifampicin
Key excretion changes in old age
Decline in kidney functions
