Ammonium Molybdate / Ammonium Tetrathiomolybdate
Ammonium Molybdate, Ammonium Tetrathiomolybdate
Also known as: Molypen · Molybdene Injectable · TTM · Ammonium tetrathiomolybdate
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Sheep
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Copper poisoning | 200 mg per head | PO | once daily | 3 weeks | 🌎 NA |
| Copper poisoning | 1.7-3.4 mg per head | IV or SC | every other day | 3 treatments | 🌎 NA |
| Copper poisoning | 100 mg with 1-gram sodium sulfate | PO | daily | — | 🌎 NA |
| Copper poisoning | 200 mg ammonium or sodium molybdate plus 500 mg of sodium thiosulfate | PO | daily | up to 3 weeks | 🌎 NA |
| Copper poisoning | 1.7 mg/kg IV or 3.4 mg/kg SC | IV/SC | every other day | 3 treatments | 🌎 NA |
| Copper poisoning | 50-500 mg ammonium molybdate and 300-1000 mg sodium thiosulfate | PO | once daily | 3 weeks | 🌎 NA |
| Copper poisoning | 2-15 mg/kg | IV | q24h | 3-6 days | 🌎 NA |
- Copper poisoning: Ammonium molybdate
- Copper poisoning: Ammonium tetrathiomolybdate
- Copper poisoning: Ammonium molybdate
- Copper poisoning: Ammonium tetrathiomolybdate
- Copper poisoning: Alternative to TTM
- Copper poisoning: Ammonium tetrathiomolybdate
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Ammonium molybdate and ammonium tetrathiomolybdate (TTM) are specialized antidotes primarily utilized in veterinary medicine for the investigational or compassionate treatment of copper poisoning in food animals, particularly sheep.
Clinical Pearl: Sheep are uniquely susceptible to copper accumulation and toxicity. These compounds are often used to rapidly bind and excrete excess systemic copper to prevent fatal hemolytic crisis and liver failure.
- Ammonium molybdate is typically administered orally and is often combined with sulfates or thiosulfates.
- Ammonium tetrathiomolybdate (TTM) is administered parenterally (IV or SC) but does not go into solution readily.
- These compounds are often sourced from chemical supply houses as there are no veterinary-labeled products available.
Mechanism of action
Molybdate interacts with sulfur and copper in the gastrointestinal tract and systemic circulation to form thiomolybdates.
- In the GI tract: Molybdate and sulfur combine to form thiomolybdates, which bind to dietary copper → forms insoluble copper-thiomolybdate complexes → prevents copper absorption and promotes excretion in feces.
- Systemically: Parenteral TTM binds to free copper in the blood and extracts copper from metallothionein in the liver → forms a stable, inert complex → safely excreted by the kidneys.
Safety & warnings
Contraindications
- Use with caution in pregnant animals (FDA Category C in humans)
Adverse effects
- Long-term toxic endocrinopathy (retention of TTM in CNS, pituitary, and adrenal glands)
- Infertility (delayed onset, 2-3 years post-treatment)
- Progressive unthriftiness and death (delayed onset)
Precautions
Regulatory Warning: It is highly recommended to contact the FDA for guidance before treating food animals with molybdate compounds.
- Withdrawal Times: FARAD recommends a minimum 10-day preslaughter withdrawal time and a minimum 5-day milk withholding interval.
- Preparation: Ammonium tetrathiomolybdate does not go into solution readily; therefore, orally administered ammonium molybdate is often preferred in field settings.
- Pregnancy: FDA Category C. Animal studies have shown adverse effects on the fetus, though adequate human/veterinary studies are lacking.
Monitoring
- Clinical signs of copper toxicity (jaundice, hemoglobinuria, weakness)
- Liver and kidney function
- Long-term monitoring for unthriftiness or reproductive failure
Pharmacokinetics
Distribution
TTM can be retained in the CNS, pituitary, and adrenal glands long-term.
Overdose
While acute overdose information is limited, long-term retention of ammonium tetrathiomolybdate (TTM) in the CNS, pituitary, and adrenal glands has been documented to cause a toxic endocrinopathy. This can result in delayed infertility, progressive unthriftiness, and death 2-3 years post-treatment.
Available products
Formulations
- Injection (human-labeled): 25 mcg/mL
- Chemical powder (for compounding oral or injectable solutions)
Veterinary
- None (obtained from chemical supply houses)
Human-labeled
- Ammonium Molybdate Injection: 25 mcg/mL (as 46 mcg/mL ammonium molybdate tetrahydrate) in 10 mL vial (Molypen)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Client information
Important Safety Note: This medication is a specific antidote used to treat copper poisoning, a life-threatening condition in sheep and other ruminants.
- Administration: Follow your veterinarian's exact dosing schedule. Oral forms are often mixed with other compounds (like sodium sulfate) to enhance effectiveness.
- Food Safety: Strictly adhere to the 10-day meat and 5-day milk withdrawal times to ensure food safety for human consumption.
- Long-term Monitoring: Treated animals may require long-term monitoring. The antidote itself can have delayed effects on fertility and overall health years after treatment.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.