Alkalinizing drugs

Alkalinizing drugs

Alkalinizing drugs are used to treat metabolic acidosis and to in-crease blood pH. These include:

·                 sodium bicarbonate

·                 sodium citrate

·                 sodium lactate

·                 tromethamine.

Increasing another pH

Sodium bicarbonate is also used to increase urine pH.

Pharmacokinetics

All of the alkalinizing drugs are absorbed well when given orally.

Metabolism and excretion

Sodium citrate and sodium lactate are metabolized to the active ingredient, bicarbonate. Sodium bicarbonate isn’t metabolized. Tromethamine undergoes little or no metabolism and is excreted unchanged in urine.

Pharmacodynamics

Sodium bicarbonate separates in the blood, providing bicarbonate ions that are used in the blood buffer system to decrease the hy-drogen ion concentration and raise blood pH. (Buffers prevent ex-treme changes in pH by taking or giving up hydrogen ions to neu-tralize acids or bases.) As the bicarbonate ions are excreted in urine, urine pH rises. Sodium citrate and lactate, after conversion to bicarbonate, alkalinize the blood and urine in the same way.

Hitching up with hydrogen

Tromethamine acts by combining with hydrogen ions to alkalinize the blood; the resulting tromethamine–hydrogen ion complex is excreted in urine.

Pharmacotherapeutics

Alkalinizing drugs are commonly used to treat metabolic acidosis. Other uses include raising urine pH to help remove certain sub-stances, such as phenobarbital, after an overdose.

Drug interactions

The alkalinizing drugs sodium bicarbonate, sodium citrate, and sodium lactate can interact with a wide range of drugs to increase or decrease their pharmacologic effects.

·                 They may increase excretion and reduce the effects of chlor-propamide, ketoconazole, lithium, and salicylates.

·                 They may reduce the excretion and increase the effects of am-phetamines, flecainide, quinidine, and pseudoephedrine.

·                 The antibacterial effects of methenamine are reduced when tak-en with alkalinizing drugs. (See Adverse reactions to alkalinizingdrugs)