AMOXICILLIN
For general information on the penicillins, including adverse effects, contraindications, overdosage, drug interactions and monitoring parameters, refer to the monograph: Penicillins, General
Information.Chemistry - An aminopenicillin, amoxicillin is commercially available as the trihydrate. It occursas a practically odorless, white, crystalline powder that is sparingly soluble in water. Amoxicillindiffers structurally from ampicillin only by having an additional hydroxyl group on the phenyl ring.
Amoxicillin may also be known as amoxycillin, p-hydroxyampicillin, or BRL 2333.
Pharmacology/
Pharmacokinetics (specific) - Amoxicillin trihydrate is relatively stable in the presence of gastricacid. After oral administration, it is about 74-92% absorbed in humans and animals (monogastric).
Food will decrease the rate, but not the extent of oral absorption and many clinicians suggest givingthe drug with food, particularly if there is concomitant associated GI distress. Amoxicillin serumlevels will generally be 1.5-3 times greater than those of ampicillin after equivalent oral doses.
After absorption the volume of distribution for amoxicillin is approximately 0.3 L/kg in humansand 0.2 L/kg in dogs. The drug is widely distributed to many tissues, including liver, lungs, prostate(human), muscle, bile, and ascitic, pleural and synovial fluids. Amoxicillin will cross into the CSFwhen meninges are inflamed in concentrations that may range from 10-60% of those found inserum. Very low levels of the drug are found in the aqueous humor, and low levels found in tears, sweat and saliva. Amoxicillin crosses the placenta, but it is thought to be relatively safe to useduring pregnancy. It is approximately 17-20% bound to human plasma proteins, primarily albumin.
Protein binding in dogs is approximately 13%. Milk levels of amoxicillin are considered to be low.
Amoxicillin is eliminated primarily through renal mechanisms, principally by tubular secretion, butsome of the drug is metabolized by hydrolysis to penicilloic acids (inactive) and then excreted in theurine. Elimination half-lives of amoxicillin have been reported as 45-90 minutes in dogs and cats, and 90 minutes in cattle. Clearance is reportedly 1.9 ml/kg/min in dogs.
Information.Chemistry - An aminopenicillin, amoxicillin is commercially available as the trihydrate. It occursas a practically odorless, white, crystalline powder that is sparingly soluble in water. Amoxicillindiffers structurally from ampicillin only by having an additional hydroxyl group on the phenyl ring.
Amoxicillin may also be known as amoxycillin, p-hydroxyampicillin, or BRL 2333.
Storage, Stability, Compatibility
Amoxicillin capsules, tablets, and powder for oral suspensionshould be stored at room temperature (15-30°C) in tight containers. After reconstitution, the oralsuspension should preferably be refrigerated (refrigeration not absolutely necessary) and any unused product discarded after 14 days. After reconstitution, the injectable veterinary suspension isstable for 3 months at room temperature and 12 months when refrigerated.Pharmacology/
Uses, Indications
Although there may be some slight differences in activityagainst certain organisms, amoxicillin generally shares the same spectrum of activity and uses asampicillin. Because it is better absorbed orally (in non-ruminants), higher serum levels may beattained than with ampicillin. Refer to the ampicillin monograph or the general penicillin statementfor more information.Pharmacokinetics (specific) - Amoxicillin trihydrate is relatively stable in the presence of gastricacid. After oral administration, it is about 74-92% absorbed in humans and animals (monogastric).
Food will decrease the rate, but not the extent of oral absorption and many clinicians suggest givingthe drug with food, particularly if there is concomitant associated GI distress. Amoxicillin serumlevels will generally be 1.5-3 times greater than those of ampicillin after equivalent oral doses.
After absorption the volume of distribution for amoxicillin is approximately 0.3 L/kg in humansand 0.2 L/kg in dogs. The drug is widely distributed to many tissues, including liver, lungs, prostate(human), muscle, bile, and ascitic, pleural and synovial fluids. Amoxicillin will cross into the CSFwhen meninges are inflamed in concentrations that may range from 10-60% of those found inserum. Very low levels of the drug are found in the aqueous humor, and low levels found in tears, sweat and saliva. Amoxicillin crosses the placenta, but it is thought to be relatively safe to useduring pregnancy. It is approximately 17-20% bound to human plasma proteins, primarily albumin.
Protein binding in dogs is approximately 13%. Milk levels of amoxicillin are considered to be low.
Amoxicillin is eliminated primarily through renal mechanisms, principally by tubular secretion, butsome of the drug is metabolized by hydrolysis to penicilloic acids (inactive) and then excreted in theurine. Elimination half-lives of amoxicillin have been reported as 45-90 minutes in dogs and cats, and 90 minutes in cattle. Clearance is reportedly 1.9 ml/kg/min in dogs.