| How is fat as reservoir? | Could be a reservoir for lipid soluble drugs as it is stable and has low blood flow.
Ex: thiopental presents in fat 3 hours after admin
Ex: insectiscide DDT
Ex: Antianxiety drug clorazepate |
| How is bone as a drug reservoir? | Tetracyclins and heavy metals accumulate and crystallizes in bone tissue
Could be toxic (lead Pb2+ poisoning)
Could be therapeutic (osteoporosis bisphosphonate make hydroxyapatite crystals reducing osteoclastic function) |
| What is drug redistribution? | Redistribution of drugs is a way of terminating the action of a drug
Drugs go to another tissue than the action mediated one.
Terminates effect of liposoluble drugs in heart and CNS like anesthetic thiopental which acts within seconds on brain, but then diffuses with time into muscles giving a rapid onset and termination of the anesthesia |
| How is the placenta drug distribution? | Critical for anomalies in children, drugs transferred through placenta are liposoluble, plasma bound, and anionized (as fetal plasma is more acidic than mothers pH=7
There are efflux proteins Pgp proteins limiting fetal exposure to toxic substances, also there are influx transporters |
| How is CNS drug distribution? | needs liposoluble drugs transport is primarily transcellular (not paracellular cause of increased tight junctions)
Imp for side effects
Ex: Loratidine antihistamine is non sedating as it is hydrophilic whereas diphenhydramine could cause sedation with antihistamine effect
Drugs may enter CNS by specific uptake transporters into brain and CSF
Also output is possible by efflux carriers (like Pgp, or OATP (also seen in GI)) |
