OSPAMOX

Indications

• Bacterial infections
• Respiratory tract infections
• Urinary tract infections
• Meningitis
• Gastrointestinal infections
• Endocarditis prophylaxis

Dosage

Children: Refer to the BNF for Children for appropriate dosing recommendations in paediatric patients.

Adults: Refer to the BNF for specific dosing guidelines based on the type and severity of infection.

Mechanism of action

Ampicillin exerts its antibacterial effect by inhibiting the synthesis of bacterial cell walls. It binds to penicillin-binding proteins (PBPs) located inside the bacterial cell wall, which interferes with the transpeptidation process necessary for forming stable cell walls. This disruption causes the bacteria to undergo lysis due to osmotic pressure, resulting in cell death.

Pharmacodynamics

Ampicillin has a time-dependent killing effect, meaning its efficacy is related to the duration of time that plasma concentrations remain above the minimum inhibitory concentration (MIC) for the target organism. Its bactericidal activity is primarily against actively dividing bacteria. Resistance can occur through the production of beta-lactamases by certain bacteria, which hydrolyze the beta-lactam ring of ampicillin, rendering it ineffective.

Pharmacokinetics

Ampicillin is absorbed from the gastrointestinal tract, with food potentially affecting its absorption. It is widely distributed throughout body tissues and fluids, including the central nervous system (CNS) in the presence of inflamed meninges. Ampicillin is primarily excreted unchanged in the urine via renal tubular secretion and glomerular filtration. Its half-life is approximately 1 to 2 hours in individuals with normal renal function, and dosage adjustments may be necessary in patients with renal impairment.

Contra-indications

• Hypersensitivity to ampicillin or other penicillins
• History of severe allergic reactions to beta-lactam antibiotics
• History of jaundice or hepatic dysfunction associated with previous use of ampicillin

Adverse effects

• Diarrhea
• Nausea
• Vomiting
• Rash
• Allergic reactions including anaphylaxis
• Clostridium difficile-associated diarrhea
• Hepatic dysfunction
• Renal impairment

Interactions

• Probenecid may inhibit the renal excretion of ampicillin, leading to increased plasma levels
• Increased risk of toxicity when combined with other nephrotoxic agents
• May reduce the effectiveness of oral contraceptives

Precautions

• Use with caution in patients with renal impairment
• Monitor for signs of allergic reactions during treatment
• Consider alternative therapy for patients with a history of severe allergies
• Be aware of potential superinfection with prolonged use

Pregnancy

Ampicillin is generally considered safe for use during pregnancy, as it does not appear to cause harm to the fetus; however, it should be used only if clearly needed.

Breast-feeding

Ampicillin is excreted in breast milk; caution is advised when administering to nursing mothers, although it is generally deemed safe.

Storage

Store in a cool, dry place away from light. Reconstituted solutions should be refrigerated and used within a specified time frame based on manufacturer guidelines.

Formulations

• Capsules
• Tablets
• Oral suspension
• Injectable solution