parmacodynamic 2

3 - metabolsim - biotransformation :

chemical alternation of drugs aiming to convert active lipophilic non-ionized drug to inactive hydrophilic ionized easily excreted metabolites

metabolism of drugs under go two phases - not always - but common

types :

a- phase 1 : non-synthetic " include

1- oxidation
2- reduction
3- hydrolysis

results oh this phase :

- convert inactive drugs to active drug 

- convert active drug to active metabolites as phenacetin to paracetamol

- convert active drug to inactive metabolites as acetyl-choline to acetic acid

b- phase 2 : synthesis " conjugation 

convert the drug to conjugation which is inactive , more water soluble

Molecules or groups

involved in phase II reactions include acetate, glucuronic acid,

glutamine, glycine and sulphate, which may combine with

reactive groups introduced during phase I metabolism (‘functionalization’)

site of biotransformation :

1- hepatic microsomal enzymes 

there are drugs induce by increase activity of hepatic enzyme so increase degardation of drug 

inducers : rifampicin , phenytoin , smoker , androgens

inhibitors : chloramphenicol , estrogen , progesterone , diazepam 

2- non-microsoaml drug biotransformation :

digestive juices , palsma , flora