Cephalosporins

By | 2011-05-09

The cephalosporins comprise a large group of antibacterials containing the beta-lactam ring. They are closely related to the penicillins. Like the penicillins they are bactericidal (operating time-dependent killing), are relatively non-toxic (although less so than the penicillins), and less likely to cause allergic reactions. Cephalosporins are suitable for use in rabbits and rodents.

It is difficult to generalise about the spectrum of activity of cephalosporins and each individual drug can be different. The tradition of classifying these drugs as first, second and third generation can cause confusion particularly as newer drugs are developed. The first generation drugs are active against a range of both Gram-positive and Gram-negative organisms comprising staphylococci (including beta-lactamase-producing strains), Pasteurella, E. coli, Actinobacillus, Actinomyces, Haemophilus, Erysipelothrix, Clostridium, and Salmonella spp. However Pseudomonas and many Proteus spp. are resistant. Successive generations of cephalosporins are characterised by being less well absorbed following oral administration (so that only first generation cephalosporins are available as oral preparations and most other cephalosporins are not suitable for oral administration), have increased stability to Gram-negative beta-lactamases, and generally increased activity against Gram-negative organisms, but reduced activity against Gram-positive organisms particularly staphylococci.

As a general rule, the second generation cephalosporins have good activity against Gram-positive organisms and the Enterobacteriaceae but are not effective against the most intractable Gram-negative organisms such as Klebsiella spp. or Pseudomonas aeruginosa. Further developments among the cephalosporins have been made to produce drugs which are effective against Klebsiella spp. or Pseudomonas aeruginosa or to produce drugs which are effective against the refractory anaerobes, such as Bacteroidesfragilis. These developments have been made sometimes at the expense of the Gram-positive spectrum, such that potency against Sta-phylococcus spp, in particular, may be reduced. Cefoperazone is an example of a cephalosporin (third generation) with activity against Pseudomonas aeruginosa. Cefoxitin is a cephalosporin which is noted for its activity against Bacteroides fragilis. Cefquinome is the most recently developed cephalosporin for veterinary use (sometimes termed fourth generation). It is extremely broad-spectrum being highly active against Enterobacteriaceae, staphylococci (including methicillin resistant strains), and enterococci. In addition, it is not destroyed by the most common plasmid or chromosomal beta lactamases of Klebsiella spp. and Pseudomonas aeruginosa.

CEFALEXIN

(Cephalexin)

Indications. Cefalexin-sensitive infections

Contra-indications. Hypersensitivity to cephalosporins or penicillins

Side-effects. Local tissue reaction; rarely salivation and vomiting in dogs

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; reduce dose in renal impairment to avoid unnecessary accumulation

Dose: Dosages vary. For guidance.

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

Dogs, cats: by mouth, 10-25 mg/kg twice daily by subcutaneous or intramuscular injection, 10 mg/kg once daily

Prescription-only medicine: Cefaseptin (Vetoquinol) UK

Tablets, f/c, cefalexin (as monohydrate) 120 mg, for dogs 5-10 kg body-weight, cats

Tablets, f/c, cefalexin (as monohydrate) 600 mg, for dogs 12-24 kg body-weight

Prescription-only medicine: Ceporex Injection (Schering-Plough) UK

Injection (oily), cefalexin (as sodium salt) 180 mg/mL, for cattle, dogs, cats

Withdrawal Periods.

Cattle: slaughter 19 days, milk withdrawal period nil.

Prescription-only medicine: Cephorum (Forum) UK

Tablets, f/c, scored, cefalexin 250 mg, for dogs

Prescription-only medicine: Ceporex Vet 50/250/500 (Schering-Plough) UK

Tablets, f/c, cefalexin 50 mg, for dogs 6-9 kg body-weight, cats

Tablets, f/c, cefalexin 250 mg, for dogs more than 10 kg body-weight

Tablets, f/c, cefalexin 500 mg, for dogs more than 26 kg body-weight

Prescription-only medicine: Ceporex Vet Oral Drops (Schering-Plough) UK Oral suspension, granules for reconstitution, cefalexin 100 mg/mL, for dogs up to 20 kg body-weight, cats. Life of reconstituted suspension 10 days Note. Store reconstituted suspension in refrigerator

Prescription-only medicine: Rilexine Tablets (Virbac) UK

Tablets, cefalexin 75 mg, for dogs, cats

Tablets, cefalexin 300 mg, 600 mg, for dogs

CEFQUINOME

Indications. Cefquinome-sensitive infections

Contra-indications. Hypersensitivity to cephalosporins or penicillins

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: By intramuscular injection.

Cattle: 1 mg/kg daily; calves: 2 mg/kg daily

Pigs: 1-2 mg/kg

Prescription-only medicine: Cephaguard (Intervet) UK

Injection (oily), cefquinome 25 mg/mL, for cattle,pigs

Withdrawal Periods.

Cattle: slaughter 5 days, milk not less than 12 hours.

Calves: slaughter 4 days.

Pigs: slaughter 3 days

CEFTAZIDIME

Indications. Ceftazidime-sensitive infections

Dose: See Prescribing for reptiles

Prescription-only medicine:® Fortum(GSK) UK

Injection, powder for reconstitution, ceftazidime (as pentahydrate) 250 mg, 500 mg, 1g, 2g, 3g

Prescription-only medicine:© Kefadim (Lilly) UK

Injection, powder for reconstitution, ceftazidime (as pentahydrate) 1 g, 2 g

CEFTIOFUR

Indications. Ceftiofur-sensitive infections

Contra-indications. Hypersensitivity to cephalosporins or penicillins

Side-effects. Transient occasional pain on injection; inflammation at site of injection

Warnings. Safety in pregnant or breeding animals has not been established

Dose:

Horses: by intramuscular injection, 2 mg/kg once daily

Cattle: by subcutaneous injection, 1 mg/kg once daily

Pigs: by intramuscular injection, 3 mg/kg once daily

Prescription-only medicine: Excenel Sterile Powder (Pfizer) UK

Injection, powder for reconstitution, ceftiofur (as sodium salt) 1 g, 4 g, for horses, cattle, pigs

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

Cattle: slaughter 8 hours, milk withdrawal period nil.

Pigs: slaughter 2 days Note. For intramuscular injection in cattle

Prescription-only medicine: Excenel RTU (Pfizer) UK

Injection, ceftiofur (as hydrochloride) 50 mg/mL, for cattle, pigs

Withdrawal Periods.

Cattle: slaughter 8 days, milk withdrawal period nil.

Pigs: slaughter 5 days

Note. For subcutaneous injection in cattle

CEFUROXIME

Indications. Cefuroxime-sensitive infections

Dose: See Prescribing for reptiles

Prescription-only medicine:® Cefuroxime (Non-proprietary) UK

Injection, powder for reconstitution, cefuroxime (as sodium salt) 250 mg, 750 mg, 1.5 g

Prescription-only medicine:® Zinacef(GSK) Wf

Injection, powder for reconstitution, cefuroxime (as sodium salt) 250 mg, 750 mg, 1.5 g