Ammonium Chloride
**Ammonium chloride** is a systemic and urinary acidifying agent used in veterinary medicine. * **Primary Uses:** Helps prevent and dissolve certain types of uroliths (e.g., struvite), enhances renal excretion of specific toxins (e.g., strontium, strychnine) or drugs (e.g., quinidine), and improves the efficacy of certain antimicrobials (like penicillins and tetracyclines) in the urinary tract. * **Metabolic Alkalosis:** Can be administered intravenously for the rapid correction of severe metabolic alkalosis. * **Clinical Pearl:** Due to the advent of highly effective struvite-dissolution diets (which inherently cause aciduria), ammonium chloride is now rarely recommended for feline struvite management. It remains a staple for urolith prevention in small ruminants, though dietary roughage-to-concentrate ratios can heavily influence its efficacy.
Mechanism: Ammonium chloride induces acidification through hepatic metabolism: * **Dissociation:** In vivo, it dissociates into **chloride** and **ammonium** ions. * **Hepatic Conversion:** The liver converts the ammonium cation to urea, releasing a **hydrogen ion (Hโบ)**. * **Acidification Pathway:** Hโบ combines with bicarbonate โ HโO + COโ. This depletes extracellular alkaline reserves, decreasing serum bicarbonate and lowering both blood and urine pH. * **Renal Excretion:** Excess chloride ions exceed tubular reabsorption capacity and are excreted alongside cations (mainly sodium) and water, causing a mild, transient **diuretic effect**.
Dosing by species
- Urolithiasis prevention ยท 300 mg/kg PO ยท PO ยท Unknown
- Urolithiasis prevention ยท 0.5-1% of the daily dry matter ยท PO ยท Daily ยท Table sugar may improve palatability
- Urolithiasis prevention ยท 300 mg/kg PO ยท PO ยท Unknown
- Urolithiasis prevention ยท 0.5-1% of the daily dry matter ยท PO ยท Daily ยท Table sugar may improve palatability
- Struvite dissolution therapy if diet and antimicrobials do not result in acid urine or to help prevent idiopathic FUS in a non-obstructed cat ยท 20 mg/kg PO twice daily ยท PO ยท q12h
- Adjunctive therapy for struvite uroliths ยท 20 mg/kg PO twice daily ยท PO ยท q12h
- Urolithiasis prevention ยท 200 mg/kg PO ยท PO ยท Unknown
- Urolithiasis prevention ยท 15-30 grams PO ยท PO ยท Unknown
- General dosing ยท 4-15 grams PO ยท PO ยท Unknown
Routes of administration
Contraindications
- Severe hepatic disease
- Uremia
- Urate calculi
- Respiratory acidosis
- Severe renal insufficiency with metabolic alkalosis secondary to vomiting
Adverse effects
- Metabolic acidosis
- Gastric irritation
- Nausea
- Vomiting
- Pain at injection site (IV)
- Increased risk of calcium oxalate urolith formation (cats)
Drug interactions
- Aminoglycosides ยท Urine acidification may diminish effectiveness in treating bacterial urinary tract infections
- Erythromycin ยท Urine acidification may diminish effectiveness in treating bacterial urinary tract infections
- Quinidine ยท Urine acidification may increase renal excretion
Monitoring
- Urine pH (goal is โค6.5)
- Blood pH (if clinical signs of toxicity or treating metabolic alkalosis)
- Serum electrolytes (with chronic use or treating metabolic acidosis)
- Carbon dioxide combining power of serum (prior to IV use to prevent serious acidosis)
Overdose
**Clinical Signs:** Nausea, vomiting, excessive thirst, hyperventilation, bradycardia or other arrhythmias, and progressive CNS depression. Laboratory results may show profound acidosis and hypokalemia. **Treatment:** * Correct acidosis by administering sodium bicarbonate or sodium acetate intravenously. * Treat hypokalemia using a suitable oral (if possible) potassium product. * Perform intense, ongoing acid-base and electrolyte monitoring until the patient is stable.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturerโs current label.