Broad-spectrum penicillins

Ampicillin and amoxicillin have slightly less activity than benzylpenicillin against Gram-positive bacteria and obligate anaerobes but considerably greater activity against Gram-negative bacteria, although their action is poor against Klebsiella, some Proteus spp., and Pseudomonas spp. In addition, they are broken down by beta-lactamases, both the staphylococcal enzymes and those produced by Gram-negative organisms such as E. coli and Haemophilus spp. Acquired resistance in such organisms has limited the usefulness of these antibiotics.

Amoxicillin is better absorbed following administration by mouth than ampicillin, giving higher plasma and tissue concentrations. Its absorption is less affected by the presence of food in the stomach. Ampicillin should be given to fasted animals and at least an hour should then elapse before food is provided. Ampicillin and amoxicillin are excreted into both bile and urine.

Depot preparations of both amoxicillin and ampicillin are available. The drug is incorporated into an oily vehicle to prolong the action of the antibacterial. Depot oil-based ampicillin preparations include aluminium monostearate in the formulation.

Pivampicillin is the pivaloyloxymethyl ester of ampicillin and as such is a prodrug. It is hydrolysed by non-specific esterases in the mucosal wall of the gastro-intestinal tract and in plasma to release ampicillin (75% by weight is converted to ampicillin).

Clavulanic acid has no significant antibacterial activity, but is a potent beta-lactamase inhibitor. Therefore, its inclusion in preparations of amoxicillin (co-amoxiclav) renders the combination active against most strains of Staph. aureus, some E. coli spp., in addition to Bacteroides and Klebsiella spp.

AMOXICILLIN

(Amoxycillin)

Indications. Amoxicillin-sensitive infections; hepatic encephalopathy

Contra-indications. Penicillin or cephalosporin hypersensitivity; gerbils, guinea pigs, hamsters, rabbits; oral administration to horses or calves with a functional rumen

Side-effects. Allergic reactions; diarrhoea

Warnings. Penicillins and cephalosporins may cause hypersensitivity (allergy) following self-injection, inhalation, ingestion, or skin contact; operators should wear suitable protective clothing; operators with known hypersensitivity should not handle these drugs; clinical signs of allergic reaction in operators include skin rash, swelling of the face, lips, or eyes, or difficulty breathing; operators should seek medical advice

Dose: Dosages vary. For guidance.

Cattle: by intramuscular injection, 7 mg/kg daily by depot intramuscular injection, 15 mg/kg, repeat after 2 days

calves: by mouth, 8 mg/kg twice daily

Sheep: by intramuscular injection, 7 mg/kg daily by depot intramuscular injection, 15 mg/kg, repeat after 2 days

Pigs: by addition to drinking water, 20 mg/kg daily by intramuscular injection, 7 mg/kg daily by depot intramuscular injection, 15 mg/kg, repeat after 2 days

Piglets: by addition to feed, 15 mg/kg body-weight daily for 14 days

Dogs, cats: by mouth, 10 mg/kg twice daily by subcutaneous or intramuscular injection, 7 mg/kg daily by depot subcutaneous or intramuscular injection, 15 mg/ kg, repeat after 2 days

Poultry: by addition to drinking water, 15-20 mg/kg

Pigeons, ducks: by addition to drinking water, 20 mg/kg

Fish: see Prescribing for fish for preparation details and dosage

Note. Amoxicillin 1 g = amoxicillin trihydrate 1.15 g

Prescription-only medicine: Amoxinsol 50 (Vetoquinol) UK

Oral powder, for addition to drinking water, amoxicillin trihydrate 500 mg/g, fovpigs, chickens, turkeys, ducks

Withdrawal Periods.

Pigs, chickens: slaughter 2 days.

Turkeys: slaughter 5 days.

Ducks: slaughter 9 days. Should not be used in birds producing eggs for human consumption

Prescription-only medicine: Amoxinsol Tablets (Vetoquinol) UK

Tablets, scored, amoxicillin (as trihydrate) 40 mg, for dogs, cats

Tablets, scored, amoxicillin (as trihydrate) 200 mg, for dogs

Prescription-only medicine: Amoxycare Capsules (Animalcare) UK

Capsules, amoxicillin (as trihydrate) 250 mg, for dogs

Prescription-only medicine: Amoxycare Injection (Animalcare) UK

Injection, amoxicillin (as trihydrate) 150 mg/mL, for cattle, sheep, pigs, dogs, cats

Withdrawal Periods.

Cattle: slaughter 10 days, milk 1 day.

Sheep: slaughter 18 days, should not be used in sheep producing milk for human consumption.

Pigs: slaughter 16 days

Prescription-only medicine: Amoxycare LA Injection (Animalcare) UK

Depot injection, amoxicillin (as trihydrate) 150 mg/mL, for cattle, sheep, pigs, dogs, cats

Withdrawal Periods.

Cattle: slaughter 21 days, milk 2.5 days.

Sheep: slaughter 16 days, should not be used in sheep producing milk for human consumption.

Pigs: slaughter 16 days

Prescription-only medicine: Amoxycare Palatable Drops (Animalcare) UK

Oral suspension, powder for reconstitution, amoxicillin (as trihydrate) 50 mg/mL, for dogs, cats. Life of reconstituted suspension 7 days

Prescription-only medicine: Amoxycare Tablets (Animalcare) UK

Tablets, scored, amoxicillin (as trihydrate) 40 mg, for dogs, cats

Tablets, scored, amoxicillin (as trihydrate) 200 mg, for dogs

Prescription-only medicine: Amoxypen Injection (Intervet) UK

Injection (oily), amoxicillin (as trihydrate) 150 mg/mL, for cattle, sheep, pigs, dogs, cats

Withdrawal Periods.

Cattle: slaughter 18 days, milk 1 day.

Sheep: slaughter 10 days, should not be used in sheep producing milk for human consumption.

Pigs: slaughter 16 days

Prescription-only medicine: Amoxypen LA (Intervet) UK

Depot injection (oily), amoxicillin (as trihydrate) 150 mg/mL, for cattle, sheep, pigs, dogs, cats

Withdrawal Periods.

Cattle: slaughter 23 days, milk 79 hours.

Sheep: slaughter 16 days, should not be used in sheep producing milk for human consumption.

Pigs: slaughter 16 days

Prescription-only medicine: Amoxypen Oral Suspension (Intervet) UK

Oral suspension, powder for reconstitution, amoxicillin (as trihydrate) 50 mg/mL, for dogs, cats. Life of reconstituted suspension 7 days

Prescription-only medicine: Betamox Injection (Norbrook) UK

Injection, amoxicillin (as trihydrate) 150 mg/mL, for cattle, sheep, pigs, dogs, cats

Withdrawal Periods.

Cattle: slaughter 18 days, milk 1 day.

Sheep: slaughter 10 days, milk from treated sheep should not be used for human consumption.

Pigs: slaughter 16 days

Prescription-only medicine: Betamox LA (Norbrook) UK

Depot injection, amoxicillin (as trihydrate) 150 mg/mL, for cattle, sheep, pigs, dogs, cats

Withdrawal Periods.

Cattle: slaughter 23 days, milk 79 hours.

Sheep: slaughter 16 days, should not be used in sheep producing milk for human consumption.

Pigs: slaughter 16 days

Prescription-only medicine: Betamox Palatable Drops (Norbook) UK

Oral suspension, powder for reconstitution, amoxicillin (as trihydrate) 50 mg/mL, for dogs, cats. Life of reconstituted suspension 7 days

Prescription-only medicine: Betamox Palatable Tablets (Norbook) UK

Tablets, scored, amoxicillin (as trihydrate) 40 mg, for dogs, cats

Tablets, scored, amoxicillin (as trihydrate) 200 mg, for dogs

Tablets, scored, amoxicillin (as trihydrate) 400 mg, for dogs

Prescription-only medicine: Bimoxyl (Bimeda) UK

Capsules, amoxicillin 250 mg, for dogs

Prescription-only medicine: Bimoxyl LA (Bimeda) UK

Depot injection (oily), amoxicillin (as trihydrate) 150 mg/mL, for cattle, sheep, pigs, dogs

Withdrawal Periods.

Cattle: slaughter 21 days, milk 3 days.

Sheep: slaughter 21 days, should not be used in sheep producing milk for human consumption.

Pigs: slaughter 11 days

Prescription-only medicine: Clamoxyl (Pfizer) UK

Tablets, scored, amoxicillin (as trihydrate) 40 mg, for dogs, cats

Tablets, scored, amoxicillin (as trihydrate) 200 mg, for dogs

Prescription-only medicine: Clamoxyl Oral Multidoser (Pfizer) UK

Mixture, amoxicillin (as trihydrate) 40 mg/dose, for piglets; dose applicator

Withdrawal Periods.

Piglets: slaughter 7 days

Dose:

Piglets: by mouth, (up to 7 kg body-weight) 1 dose twice daily, (7-15 kg body-weight) 2 doses twice daily

Prescription-only medicine: Clamoxyl LA (Pfizer) UK

Depot injection (oily), amoxicillin (as trihydrate) 150 mg/mL, for cattle, sheep, pigs, dogs, cats

Withdrawal Periods.

Cattle: slaughter 21 days, milk 4 days.

Sheep: slaughter 21 days, should not be used in sheep producing milk for human consumption.

Pigs: slaughter 21 days

Prescription-only medicine: Clamoxyl Ready to Use Injection (Pfizer) UK

Injection, amoxicillin (as trihydrate) 150 mg/mL, for cattle, sheep, pigs, dogs, cats

Withdrawal Periods.

Cattle: slaughter 21 days, milk 2 days.

Sheep: slaughter 35 days, milk from treated sheep should not be used for human consumption.

Pigs: slaughter 14 days

Prescription-only medicine: Duphamox (Fort Dodge) UK

Tablets, scored, amoxicillin (as trihydrate) 40 mg, for dogs, cats

Tablets, scored, amoxicillin (as trihydrate) 200 mg, for dogs

Prescription-only medicine: Duphamox (Fort Dodge) UK

Injection, amoxicillin (as trihydrate) 150 mg/mL, for cattle, sheep, pigs, dogs, cats

Withdrawal Periods.

Cattle: slaughter 18 days, milk 1 day.

Sheep: slaughter 10 days, should not be used in sheep producing milk for human consumption.

Pigs: slaughter 16 days

Prescription-only medicine: Duphamox LA (Fort Dodge) UK

Depot injection, amoxicillin (as trihydrate) 150 mg/mL, for cattle, sheep, pigs, dogs, cats

Withdrawal Periods.

Cattle: slaughter 21 days, milk 2.5 days.

Sheep: slaughter 21 days, should not be used in sheep producing milk for human consumption.

Pigs: slaughter 21 days

Prescription-only medicine: Duphamox Palatable Drops (Fort Dodge)

Oral suspension, powder for reconstitution, amoxicillin (as trihydrate) 50 mg/mL, for dogs, cats. Life of reconstituted suspension 7 days

Prescription-only medicine: Stabox 5% Premix (Virbac) UK

Premix, amoxicillin 50 g/kg, for weaned piglets

Withdrawal Periods.

Pigs: slaughter 4 days

Prescription-only medicine: Trioxyl LA (Tulivin) UK

Depot injection (oily), amoxicillin (as trihydrate) 150 mg/mL, for cattle, sheep, pigs

Withdrawal Periods.

Cattle: slaughter 21 days, milk 5 days.

Sheep: slaughter 21 days, should not be used in sheep producing milk for human consumption.

Pigs: slaughter 21 days

Prescription-only medicine: Vetremox (Alpharma) UK

Oral powder, for addition to drinking water, amoxicillin trihydrate 100%, for chickens, turkeys

Withdrawal Periods.

Chickens: slaughter 24 hours.

Turkeys: slaughter 5 days. Should not be used in chickens or turkeys laying eggs for human consumption

Prescription-only medicine: Vetremox Pigeon (Genitrix) UK

Oral powder, for addition to drinking water, amoxicillin trihydrate 100%, for pigeons

Withdrawal Periods. Should not be used in pigeons intended for human consumption or laying eggs for human consumption

Prescription-only medicine: Vetrimoxin Paste (Ceva) UK

Oral paste, amoxicillin (as trihydrate) 20 mg/mL, for small dogs, cats; metered dose applicator

AMOXICILLIN with CLAVULANIC ACID

(Co-amoxiclav: preparations of amoxicillin (as trihydrate or the sodium salt) and clavulanic acid (as potassium clavulanate); the proportions are expressed in the form x/y, where x and y are the strengths in milligrams of amoxicillin and clavulanic acid respectively)

Indications. Amoxicillin-sensitive infections including beta-lactamase-producing micro-organisms

Contra-indications. Penicillin or cephalosporin hypersensitivity; gerbils, guinea pigs, hamsters, rabbits; oral administration to horses or calves with a functional rumen

Side-effects. Allergic reactions; diarrhoea

Warnings. Penicillins and cephalosporins may cause hypersensitivity (allergy) following self-injection, inhalation, ingestion, or skin contact. Operators with known hypersensitivity should not handle these drugs. Clinical signs of allergic reaction in operators include skin rash, swelling of the face, lips, or eyes, or difficulty breathing. Operators should seek medical advice

Dose: Expressed as amoxicillin

Cattle: by intramuscular injection, 7 mg/kg once daily calves: by mouth, 5-10 mg/kg twice daily

Pigs: by intramuscular injection, 7 mg/kg once daily

Dogs, cats: by mouth, 10-20 mg/kg twice daily by subcutaneous or intramuscular injection, 7 mg/kg once daily

Prescription-only medicine: Nisamox Tablets (Fort Dodge) UK

Tablets, scored, amoxicillin (as trihydrate) 40 mg, clavulanic acid (as potassium salt) 10 mg, for dogs

Tablets, scored, amoxicillin (as trihydrate) 200 mg, clavulanic acid (as potassium salt) 50 mg, for dogs

Prescription-only medicine: Noroclav Injection (Norbook) UK

Injection, amoxicillin (as trihydrate) 140 mg, clavulanic acid (as potassium salt) 35 mg/mL, for cattle

Withdrawal Periods.

Cattle: slaughter 42 days, milk 80 hours

Prescription-only medicine: Noroclav Tablets (Norbrook) UK

Tablets, scored, amoxicillin (as trihydrate) 40 mg, clavulanic acid (as potassium salt) 10 mg, for dogs

Tablets, scored, amoxicillin (as trihydrate) 200 mg, clavulanic acid (as potassium salt) 50 mg, for dogs

Prescription-only medicine: Synulox 500 mg Bolus (Pfizer) UK

Tablets, f/c, scored, amoxicillin (as trihydrate) 400 mg, clavulanic acid (as potassium salt) 100 mg, for calves

Withdrawal Periods.

Calves: slaughter 4 days

Prescription-only medicine: Synulox Palatable Drops (Pfizer) UK

Oral suspension, powder for reconstitution, amoxicillin (as trihydrate) 40 mg, clavulanic acid (as potassium salt) 10 mg/mL, for dogs, cats. Life of reconstituted suspension 7 days (1 drop = amoxicillin 2.3 mg)

Prescription-only medicine: Synulox Palatable Tablets (Pfizer) UK

Tablets, scored, amoxicillin (as trihydrate) 40 mg, clavulanic acid (as potassium salt) 10 mg, for dogs, cats

Tablets, scored, amoxicillin (as trihydrate) 200 mg, clavulanic acid (as potassium salt) 50 mg, for dogs

Tablets, scored, amoxicillin (as trihydrate) 400 mg, clavulanic acid (as potassium salt) 100 mg, for dogs

Prescription-only medicine: Synulox Ready to Use Injection (Pfizer) UK

Injection, amoxicillin (as trihydrate) 140 mg, clavulanic acid (as potassium salt) 35 mg/mL, for cattle, pigs, dogs, cats

Withdrawal Periods.

Cattle: slaughter 42 days, milk 60 hours.

Pigs: slaughter 31 days

AMPICILLIN

Indications. Ampicillin-sensitive infections

Contra-indications. Penicillin or cephalosporin hypersensitivity; gerbils, guinea pigs, hamsters, rabbits; oral administration to horses or calves with a functional rumen; severe renal impairment with anuria and oliguria in cats; presence of beta-lactamase producing bacteria

Side-effects. Allergic reactions; diarrhoea; occasional reaction at site of injection

Warnings. Penicillins and cephalosporins may cause hypersensitivity (allergy) following self-injection, inhalation, ingestion, or skin contact. Operators with known hypersensitivity should not handle these drugs. Clinical signs of allergic reaction in operators include skin rash, swelling of the face, lips, or eyes, or difficulty breathing. Operators should seek medical advice

Dose:

Horses: by intramuscular injection, 7.5 mg/kg once daily

Cattle, sheep: by intramuscular injection, 7.5 mg/kg once daily by depot intramuscular injection, 15 mg/kg, repeat after 2 days

Pigs: by intramuscular injection, 7.5 mg/kg once daily by depot intramuscular injection, 25 mg/kg, repeat after 2 days

Dogs: by mouth, 10-20 mg/kg twice daily given on an empty stomach

by subcutaneous or intramuscular injection, 7.5 mg/kg once daily

by depot subcutaneous injection, 15 mg/kg, repeat after 2 days

Cats: by mouth, 10-20 mg/kg twice daily given on an empty stomach

by subcutaneous or intramuscular injection, 7.5 mg/kg once daily

by depot subcutaneous injection, 20 mg/kg, repeat after 2 days

Prescription-only medicine: Amflpen Tablets (Intervet) UK

Tablets, ampicillin 50 mg, 125 mg, for dogs, cats

Tablets, ampicillin 500 mg, for dogs

Prescription-only medicine: Amfipen 15% (Intervet) UK

Injection (oily), ampicillin 150 mg/mL, for horses, dogs, cats

Withdrawal Periods. Should not be used in horses intended for human consumption

Prescription-only medicine: Amflpen LA (Intervet)

Depot injection (oily), ampicillin 100 mg/mL with aluminium monostearate, for cattle, sheep, pigs, dogs, cats

Withdrawal Periods.

Cattle: slaughter 60 days, milk 7 days.

Sheep: slaughter 60 days, should not be used in sheep producing milk for human consumption.

Pigs: slaughter 60 days

Accidental self-injection with oil-based formulations can cause severe pain and intense swelling, which may result in ischaemic necrosis and loss of a digit. Prompt medical attention is essential.

Prescription-only medicine: Ampicaps (Bimeda) UK

Capsules, ampicillin (as trihydrate) 250 mg, for dogs more than 10 kg body-weight

Prescription-only medicine: Ampicare (Animalcare) UK

Capsules, ampicillin (as trihydrate) 250 mg, for dogs more than 10 kg body-weight

Prescription-only medicine: Ampitab (Vetoquinol) UK

Oral suspension, ampicillin (as trihydrate) 380 mg/mL, for cats

Tablets, ampicillin (as trihydrate) 50 mg, 180 mg, for dogs

Prescription-only medicine: Duphacillin (Fort Dodge) UK

Injection (oily), ampicillin (as trihydrate) 150 mg/mL, for cattle, sheep, pigs

Withdrawal Periods.

Cattle: slaughter 18 days, milk 1 day.

Sheep: slaughter 18 days, should not be used in sheep producing milk for human consumption.

Pigs: slaughter 18 days

Prescription-only medicine: Norobrittin (Norbrook) UK

Injection (oily), ampicillin (as trihydrate) 150 mg/mL, for cattle, sheep, pigs

Withdrawal Periods.

Cattle: slaughter 18 days, milk 1 day.

Sheep: slaughter 18 days, should not be used in sheep producing milk for human consumption.

Pigs: slaughter 18 days