Usage
Ampicillin + Cloxacillin is a combination antibiotic medication primarily prescribed for bacterial infections caused by susceptible gram-positive and some gram-negative bacteria. It falls under the pharmacological classification of beta-lactam antibiotics, specifically penicillins. This combination is effective against bacteria that produce penicillinase, an enzyme that can break down penicillin, making it ineffective. The mechanism of action involves inhibiting bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs). This disrupts cell wall construction, ultimately leading to bacterial cell death.
Alternate Names
Ampicillin + Cloxacillin is also known as Ampiclox or Axylin, along with various other brand names depending on the manufacturer and region.
How It Works
Pharmacodynamics: Ampicillin + Cloxacillin exerts a bactericidal effect. It inhibits bacterial cell wall synthesis by binding to and inactivating penicillin-binding proteins (PBPs) located on the inner membrane of the bacterial cell wall. This action prevents the formation of cross-links in the peptidoglycan layer, a crucial component for cell wall stability. Consequently, the bacterial cell wall weakens, leading to cell lysis and death.
Pharmacokinetics:
- Absorption: Ampicillin is well-absorbed orally, but food can interfere with its absorption. Cloxacillin is also absorbed orally, but to a lesser extent than ampicillin.
- Distribution: Both drugs are widely distributed throughout the body, reaching therapeutic concentrations in various tissues and fluids, including pleural, pericardial, synovial, and ascitic fluids.
- Metabolism: Both drugs undergo some metabolism in the liver.
- Elimination: Ampicillin and Cloxacillin are primarily eliminated by the kidneys through renal excretion.
Dosage
Standard Dosage
Adults:
Oral: 250-500 mg every 6 hours.
IV/IM: 500mg to 1g every 4-6 hours.
The dose may be increased up to 2g every 6 hours orally for severe infections. The IV/IM maximum daily dose is 12g.
Children:
Oral: Ampicillin/Cloxacillin 125mg every 6 hours.
Neonates: 90mg (60mg ampicillin/30mg cloxacillin) every 4 hours.
Pediatric dosage is often calculated based on weight (25-50mg/kg/day), divided into 4 doses, with a maximum dose of 2g/day.
Special Cases:
- Elderly Patients: Dose adjustments may be needed based on renal function.
- Patients with Renal Impairment: Dosage should be reduced based on creatinine clearance.
- Patients with Hepatic Dysfunction: Dose adjustments may be needed.
- Patients with Comorbid Conditions: Caution is advised in patients with allergies to penicillins, cephalosporins, or other beta-lactam antibiotics.
Clinical Use Cases
Dosage for specific medical settings often follows standard adult or pediatric guidelines adjusted according to the severity of the infection.
Dosage Adjustments
Dose adjustments are crucial in patients with renal or hepatic impairment. Consult specific guidelines for appropriate adjustments based on creatinine clearance or liver function tests.
Side Effects
Common Side Effects:
- Diarrhea
- Nausea
- Vomiting
- Rash
Rare but Serious Side Effects:
- Allergic reactions (anaphylaxis)
- Cholestatic jaundice
- Hepatitis
- Neutropenia
- Agranulocytosis
- Clostridium difficile-associated diarrhea
Long-Term Effects:
Prolonged use can lead to antibiotic resistance and superinfections (fungal or bacterial).
Adverse Drug Reactions (ADR):
Severe allergic reactions, such as anaphylaxis, require immediate medical intervention.
Contraindications
- Hypersensitivity to penicillins, cephalosporins, or other beta-lactam antibiotics.
- Infectious mononucleosis.
Drug Interactions
- Antibiotics: Bacteriostatic antibiotics (e.g., tetracyclines, chloramphenicol) may antagonize the bactericidal action of Ampicillin + Cloxacillin.
- Anticoagulants: May enhance the effect of warfarin.
- Methotrexate: Ampicillin may decrease the excretion of methotrexate, potentially increasing its toxicity.
- Allopurinol: Concurrent use can increase the risk of skin rash.
- Probenecid: May increase and prolong blood levels of Ampicillin + Cloxacillin.
- Oral contraceptives: May reduce the efficacy of combined oral contraceptives.
- Quinoline antimalarials: May reduce the bioavailability of Ampicillin+Cloxacillin.
Pregnancy and Breastfeeding
Caution is advised during pregnancy and breastfeeding. Use only if the potential benefit outweighs the risk to the fetus or infant. Trace amounts of penicillins can be detected in breast milk. Monitor infants for potential side effects.
Drug Profile Summary
- Mechanism of Action: Inhibits bacterial cell wall synthesis.
- Side Effects: Diarrhea, nausea, vomiting, rash, allergic reactions.
- Contraindications: Hypersensitivity to penicillins, cephalosporins, infectious mononucleosis.
- Drug Interactions: Various drug interactions exist, especially with other antibiotics, anticoagulants, methotrexate, and allopurinol.
- Pregnancy & Breastfeeding: Use with caution; monitor infants.
- Dosage: Varies depending on age, condition, and route of administration.
- Monitoring Parameters: Renal function, liver function, complete blood count (CBC), and observation for signs of allergic reaction.
Popular Combinations
Combined use with aminoglycosides may broaden the spectrum of antimicrobial activity in certain cases.
Precautions
- Assess for allergies to penicillins and cephalosporins before administration.
- Monitor renal and hepatic function, especially with prolonged use.
- Observe for signs of superinfection.
- Advise patients about potential side effects and drug interactions.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Ampicillin + Cloxacillin?
A: The recommended dosage varies depending on the patient’s age, the severity of the infection, and the route of administration. See above for detailed guidelines.
Q2: What are the common side effects?
A: Common side effects include diarrhea, nausea, vomiting, and skin rash.
Q3: What are the contraindications for this medication?
A: This medication is contraindicated in patients with a known hypersensitivity to penicillins or cephalosporins, and in patients with infectious mononucleosis.
Q4: Can Ampicillin + Cloxacillin be used during pregnancy?
A: Use with caution during pregnancy only if the potential benefit outweighs the potential risk to the fetus.
Q5: Does this drug interact with other medications?
A: Yes, significant drug interactions can occur. Inform your doctor about all other medications you are taking. Key interactions include allopurinol, probenecid, methotrexate, anticoagulants like warfarin, and oral contraceptives.
Q6: How should Ampicillin + Cloxacillin be administered?
A: It can be administered orally, intravenously (IV), or intramuscularly (IM), following prescribed dosage guidelines. Oral administration should be done preferably 30 minutes before or 2 hours after meals.
Q7: What should I monitor in patients receiving this medication?
A: Monitor patients for signs of allergic reactions, renal and hepatic function, and any evidence of superinfection.
Q8: What are the signs of an allergic reaction to this medication?
A: Allergic reactions can range from mild skin rashes to severe anaphylaxis. Seek immediate medical attention if any signs of an allergic reaction occur.
Q9: Can this drug be used in patients with renal impairment?
A: Yes, but dosage adjustments are necessary based on the degree of renal impairment.
Q10: What if a patient misses a dose?
A: Take the missed dose as soon as remembered, unless it is close to the next scheduled dose. Do not double the dose to catch up.
