Alkaline diuresis is done for treatment of poisoning due to:

* Phenobarbitone- is a derivative of barbituric acid (weakly acidic drug) and its excretion can be enhanced by making the urine alkaline. * Tubular reabsorption depends on the lipid solubility. If a drug is lipid soluble, more of it will be reabsorbed and less will be excreted. Opposite is true for lipid insoluble drugs. * As lipid solubility depends on ionization, the ionized drug will be excreted by the kidney. Thus, in acidic drug poisoning (salicylate, barbiturates etc.) urine should be alkalinized with sodium bicarbonate because weak acids are in ionized form in alkaline urine and thus are easily excreted. * Similarly, for basic drug poisoning (e.g. morphine, amphetamine etc.), urine should be acidified using ammonium chloride.