Competitive antagonists bind to receptors without producing biological effects. Increasing the concentration of agonists will reverse the effect of competitive antagonists. In contrast the effect of noncompetitive antagonists cannot be reversed by agonist

Antibodies anticancer drugs inhibit the binding of cancer promoting ligands to their receptors on the cancer cells. Antimetabolites interfere with synthesis of DNA components. Microtubules inhibitors are mainly natural products. Steroid hormones agonists

Bioavailability is defined as the percentage of the drug which reach systematic circulation. At steady state the intravenous administration rate equal to clearance multiply by concentration. Bioavailability of the drug affect the rate of administration of

Cholinergic agonists involve the direct agonists at the muscarinic or nicotinic receptors. The indirect acting agonists inhibit acetylcholinesterase enzyme. Cholinergic antagonists are divided into muscarinic blockers or nicotinic blockers which is divide

Drug for hyperlipidemia. It decreases LDL synthesis, Increases fatty acid degradation. Decreases TAG formation. Additionally it enhance synthesis of apoproteins AI and AII which result in enhancement of HDL synthesis.

Free fatty acids are released from adipose into blood then to hepatocytes. In the liver free fatty acids are incorporated into VLDL which is released into the blood where it transformed to LDL. Niacin anti- hyperlipidemic drug inhibit the release of free

COX-1 and COX-2 isozymes catalyze the production of eicosanoids, such as prostaglandins, prostacyclin and thromboxane from arachidonic acids. Non selective NSAIDs inhibit both COX-1 and COX-2 thus suppress the inflammatory mediators. Selective COX-2 avoid

Partial agonist when binds to empty or receptors occupied by full agonist they produce biological effect that is weaker than full agonists. So partial agonists are better that nothing when occupied to empty receptors but works more as antagonists when bin

Proton pumps (H/K ATPase) in the parietal is the main regulator of gastric acidity. It excrete hydrogen into parietal cells in exchange of K ions. Gastrin, acetycholine and histamine H2 enhance the activity whereas prostaglandins E2 diminish the activity

The glucose molecules transported into the β cells of islets of Langerhans are rapidly metabolized to produce ATP which in turn close the ATP sensitive potassium K channels. Closure of K channels results opening of voltage sensitive calcium Ca channels. C

Estradiol derived from cholesterol in the adipose tissues and ovaries enhances the proliferation of breast cancer cells. Tamoxifen which is selective estrogen receptor modulator antagonize the estradiol effect on the cancer cells.