What is Acidic drug is more ionized at- and explain in detail?
Ans. is 'a' i.e., Alkaline pH Implication of ionization Acidic drugs ionize more at alkaline pH. o Basic drugs ionize more at acidic pH. o Unionized drug is lipid-soluble and diffusible. o Ionised drug is lipid-insoluble and nondiffusible. o Acidic drugs (salicylates, barbiturates) are predominently unionized in acid gastric juice and are absorbed from stomach. Basic drugs (morphine, quinine) are predominently unionized in intestinal alkaline pH and are absorbed from intestine. o In the stomach acidic drug (aspirin, pKa - 3.5) arc unionised (lipid soluble & diffusable) and so diffuses into gastric epithelial cells. In gastric epithelial cell, it will ionize (pH-7.4) becomes less diffusable and so will localize there. This ion trapping is one mechanism where by aspirin is concentrated in, and so harms, gastric mucosa. o Basic drugs attain higher concentration intracellularly (pH 7.0 Vs 7.4 of plasma). o Acidic drugs are ionized more in alkaline urine - do not back diffuse in the kidney tubules and arc excreted faster. o Similarly basic drugs are excreted faster in acidic urine.