VPT 311: General and Systemic Veterinary Pharmacology (2+1)

ALKALISATION OF URINE

Alteration of urine pH

Alteration is sometimes desirable as in the case of poisoning and in the excretion of some drugs to prevent side effects.

Alkalinisation of urine

• Alkalinising agents reduce the irritation of an inflamed urinary tract and discourage the growth of certain organisms like E.coli.
• Urine can be made alkaline by sodium bicarbonate intravenous administration or by potassium citrate oral administration.
• Sodium or potassium citrate is metabolised to form a stable cation (Na⁺ or K⁺) and a labile anion (citrate).
• Citrate is taken up for use by the TCA. The Na⁺ or K⁺ is excreted with the most common anion (HCO3^-.
• Hence, there will be alkaline urine.

Administration and use

• To decrease the adverse effects of sulphonamides alkalinisation is useful. Sulphonamides are generally insoluble in acid urine. They may thus precipitate out and crystallise. Therefore, to increase solubility, the urine is made more alkaline.
• To increase the excretion of acidic drugs like Aspirin, salicylates and barbiturates.
• Alkalinisation of urine increases the antibacterial activity of aminoglycosides in urinary tract infection.
• Alkalinisation of the urine in usually recommended to prevent the recurrence of urate stones in dogs after cystotomy. Sodium bicarbonate at 0.5 to 1.0 g is given orally thrice daily.