Cefalexin

Products

Cefalexin is commercially available as a veterinary drug in the form of tablets, chewable tablets, and suspensions. It is available both as a monopreparation (e.g., Cefacat, Cefadog) and in combination with kanamycin (Ubrolexin). It has been approved in many countries since 1986.

Structure and properties

Cefalexin (C16H17N3O4S , Mr = 347.4 g/mol) exists as a white crystalline powder. It has a characteristic odor and is highly soluble in water. The monohydrate is used. It is acid stable and does not decompose in the stomach. Cefalexin is a semisynthetic derivative of cephalosporin C obtained from the fungal species. The core structure of cefalexin is a β-lactam ring, which is responsible for its bactericidal activity.

Effects

Cefalexin (ATCvet QJ01DB01, ATCvet QJ51DA01) is bactericidal with a broad spectrum of activity. It belongs to the 1st-generation cephalosporin group and is therefore primarily active against Gram-positive pathogens (especially against ), but also against some Gram-negative germs. Susceptible bacteria include staphylococci (including penicillinase-producing), streptococci, pneumococci, clostridia, E. coli, klebsia, salmonella, and shigella. Cefalexin acts in a time-dependent manner and only on pathogens that are growing.

Mechanism of action

Antibacterial action is due to disruption of bacterial cell wall synthesis. Bacterial murein transpeptidase is inhibited, preventing cross-linking of bacterial cell wall murein. Damage to the bacterial cell structure occurs. This results in high osmotic pressure inside the bacterial cell, which eventually leads to its dissolution.

Indications

For the treatment of bacterial infectious diseases in dogs, cats, and cows. Dogs and cats:

  • Urinary tract infections
  • Infections of the skin such as inflammation of the skin and hair follicles.
  • Superficial pyoderma (purulent skin inflammation) in dogs.
  • Severe respiratory infections in the cat.
  • Wounds and abscesses in cats

Dairy cows:

  • Udder inflammation (mastitis)

Dosage

According to the SmPC. Cefalexin is administered orally to dogs and cats. It should be taken with feeding to avoid side effects such as vomiting. Cows are injected into the teats (intramammary). Cefalexin is given twice daily.

Contraindications

Because of cross-allergies, cefalexin is contraindicated in cases of hypersensitivity to β-lactam antibiotics. This also applies to the user. Direct contact with the drug should be avoided. In case of resistance to cefalexin, cross-resistance to other β-lactam antibiotics is to be expected. In cases of chronic renal insufficiency, the dose must be adjusted or the interval between administrations extended. For complete precautions, see the drug label.

Interactions

Cefalexin should not be co-administered with antibiotics that have bacteriostatic activity, such as tetracyclines, chloramphenicol, sulfonamides, and macrolides, because antibacterial activity is impaired. The combination of cefalexin with aminoglycosides, polymyxin B and colistin, methoxyflurane, furosemide, and etacrynic acid may result in the potentiation of possible renal impairment.

Adverse effects

Adverse effects include allergic reactions and gastrointestinal symptoms in the form of occasional vomiting, diarrhea, increased salivation, loss of appetite, and listlessness. Vomiting and diarrhea can be avoided by administering the drug together with food. In case of overdose, mainly digestive symptoms such as vomiting and diarrhea occur.