Ampik capsules

Indications

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

Dosage

Children: Refer to the BNF for Children for age-specific dosing recommendations.

Adults: Refer to specific guidelines or the BNF for exact dosing recommendations. Dosing may vary based on the type and severity of infection.

Mechanism of action

Ampicillin exerts its antibacterial effects by binding to penicillin-binding proteins (PBPs) located on the inner membrane of the bacterial cell wall. This binding inhibits the transpeptidation reaction, which is crucial for cross-linking peptidoglycan layers in the bacterial cell wall, ultimately leading to cell lysis and death due to osmotic instability.

Pharmacodynamics

The pharmacodynamics of ampicillin involve its time-dependent antibacterial activity, where the efficacy of the drug is related to the duration of time that plasma concentrations are above the minimum inhibitory concentration (MIC) for the target organism. It demonstrates a post-antibiotic effect (PAE), meaning that bacterial growth remains inhibited even after drug levels have fallen below the MIC.

Pharmacokinetics

Ampicillin is well absorbed after oral administration, with a bioavailability of approximately 40-60%. It is widely distributed in body tissues and fluids, including the central nervous system in cases of meningitis. The drug is primarily excreted unchanged in the urine, with renal clearance being a significant route of elimination. The half-life of ampicillin is approximately 1-2 hours in healthy individuals, but it can be prolonged in patients with renal impairment.

Contra-indications

• History of hypersensitivity to penicillins or cephalosporins
• Severe renal impairment (with caution)
• Mononucleosis (risk of rash)

Adverse effects

• Allergic reactions (rash, anaphylaxis)
• Gastrointestinal disturbances (nausea, vomiting, diarrhea)
• Hematological reactions (eosinophilia, thrombocytopenia)
• Clostridium difficile-associated diarrhea
• Nephrotoxicity (rare)

Interactions

• Probenecid (increased ampicillin levels)
• Methotrexate (increased toxicity of methotrexate)
• Allopurinol (increased risk of skin rash)
• Anticoagulants (enhanced effect)

Precautions

• Caution in patients with renal impairment
• Use with caution in patients with a history of allergy to other beta-lactam antibiotics
• Monitor for signs of superinfection (especially with prolonged use)

Pregnancy

Ampicillin is classified as category B. It is generally considered safe but should be used only if clearly needed.

Breast-feeding

Ampicillin is excreted in breast milk. It is generally considered safe, but caution is advised due to potential effects on the infant.

Storage

Store below 25 degrees Celsius in a dry place, protected from light. Reconstituted solutions should be refrigerated and used within 7 days.

Formulations

• Capsules (250 mg, 500 mg)
• Oral suspension (125 mg/5 mL, 250 mg/5 mL)
• Injection (500 mg, 1 g, 2 g)