CAS No.: 137-88-2
Amprolium Hydrochloride is a synthetic antiprotozoal agent primarily used as a coccidiostat in veterinary medicine and animal husbandry. Structurally, it is a pyrimidine derivative designed as a thiamine (Vitamin B1) analog, which enables it to selectively interfere with thiamine metabolism in coccidia parasites while exhibiting relatively low toxicity to host animals.
It is widely registered and used globally across poultry, cattle, sheep, and rabbit farming systems, either as a standalone feed additive or in combination with other anticoccidial agents such as Ethopabate.
Mechanism:
Amprolium Hydrochloride exerts its anticoccidial effect by acting as a competitive antagonist of thiamine (Vitamin B1) :
Coccidia parasites require thiamine for normal carbohydrate metabolism and energy production.
Amprolium competitively inhibits thiamine uptake by the parasite, disrupting its intracellular thiamine utilization.
Without adequate thiamine metabolism, the parasite cannot sustain normal development, leading to arrested growth and eventual elimination.
Because mammalian hosts metabolize thiamine differently and have alternative compensatory pathways, Amprolium exhibits selective toxicity toward parasites with relatively lower acute toxicity to the host animal when used appropriately.
This mechanism makes Amprolium particularly useful as a prophylactic agent in continuous feeding programs, although it can also be deployed in therapeutic doses during early-stage outbreaks.
Spectrum of Activity:
Amprolium Hydrochloride is effective against multiple Eimeriaspecies across different animal hosts:
Poultry
Eimeria tenella— cecal coccidiosis (highly sensitive)
Eimeria necatrix— intestinal coccidiosis (moderate sensitivity)
Eimeria acervulina— mild to moderate infections
Eimeria maxima— limited standalone activity; often paired with Ethopabate
Eimeria brunetti— limited standalone activity; often paired with Ethopabate
Ruminants
Eimeria bovis— calf coccidiosis
Eimeria zuernii— cattle and sheep coccidiosis
Other Species
Eimeria stiedae— rabbit hepatic coccidiosis
Various Isosporaspecies affecting dogs and cats (off-label use)
⚠️ Limitation Note: Amprolium has limited standalone activity against E. maximaand E. brunetti. For comprehensive protection, it is frequently formulated in combination with Ethopabate (e.g., Amprolium 250 g/kg + Ethopabate 16 g/kg premix), which extends coverage to these resistant species.
Applications by Animal Species:
🐔 Poultry (Broilers, Layers, Turkeys)
Primary use: Prevention and control of caecal and intestinal coccidiosis
Administration routes: Feed premix, oral drench, or drinking water (via compounded oral solution)
Key advantage: Can be used in replacement pullets and breeding stock where ionophore carryover is a concern
🐄 Cattle and Calves
Primary use: Prevention of calf coccidiosis caused by E. bovisand E. zuernii
Administration: Oral bolus, drench, or medicated feed
Strategic timing: Often administered during weaning, transport, or confinement periods when coccidial challenge peaks
🐑 Sheep and Goats
Primary use: Control of ovine coccidiosis, particularly in lambs
Administration: Oral drench or medicated water
Note: Lambs are highly susceptible; early intervention prevents severe enteritis and mortality
🐰 Rabbits
Primary use: Prevention of hepatic coccidiosis (E. stiedae)
Administration: Medicated feed or drinking water
Benefit: Reduces liver damage and improves growth performance.
