Question

1. Why do drugs not have the same effect on all patients?

Answer 1

factors affecting drug action -

body size-large person generally needs more of a drug than a small person needs for the same effect

pregnancy-drug absorption is affected by slower gastric emptying and slower bowel and colonic transit time.The increased plasma volume ,change in protein binding ,and lower ratio of lean muscle to adipose tissue during pregnancy may result ina greater volume of drug distribution for lipophilic drug

lactation - generally drugs that are poorly absorbed or have high first -pass metabolism are less likely to be problematical during breast feeding

age-infants and older people particularly have problems with drug response because their liver and kidney function less effectively,so drug that are broken down by the liver or excreted by the kidneys tend to accumulate,

genetic factors-many medicines are metabolised by the cytochrome p450 super-family of enzymes.The term cytochrome P450is a generic term for the entire family of enzymes.Under this system,the P450 enzymes are divided into families and subfamilies.The activity of metabolising enzyme such as the cytochrome P450 is influenced by variety of factors ,including genetic difference between people ,enzyme inhibitionand induction,diet,healthstatus,gender and age

disease status -the absorption,distribution,metabolism and elimination of drugs can be influenced by the physiological and biochemical changes that occur due to various diseases for example hepatic diseases may slow drug metabolism

route of drug administration-drug absorption various according to route of administration

Tolerance and resistance- depends on the overall health status of the patient

PHYSIOLOGICAL FACTORS AFFECTING DRUG ABSORPTION ARE ,

Age,gastric emptying,intestinal transit,gastro intestinal PH, DISEASE STATE,Gastro intestinal contents,Presystemic metabolism