Usage
Cefalexin + Clavulanic Acid is prescribed for a wide range of bacterial infections, including skin and soft tissue infections (such as impetigo, furuncles, erysipelas, cellulitis, and mastitis), respiratory tract infections (including pneumonia, strep throat, and upper respiratory tract infections), urinary tract infections (including cystitis and pyelonephritis), bone infections, otitis media, and genitourinary tract infections. It is also used in postpartum upper genital tract infections, as a second-line treatment of acute otitis media and acute sinusitis, and in parenteral to oral switch therapy in severe infections. It’s particularly effective against beta-lactamase-producing strains of Staphylococcus aureus. This combination is not effective against viral infections like the common cold or flu.
Its pharmacological classification is antibiotic, specifically a combination of a beta-lactam antibiotic (cephalexin) and a beta-lactamase inhibitor (clavulanic acid).
Cefalexin inhibits bacterial cell wall synthesis, leading to bacterial death. Clavulanic acid enhances cefalexin’s effectiveness by inhibiting beta-lactamase, an enzyme produced by some bacteria that can break down cefalexin.
Alternate Names
While “Cefalexin + Clavulanic Acid” is the generic name, this combination is often referred to as Co-Amoxiclav when amoxicillin is combined with clavulanic acid. There isn’t a common combined name for specifically cefalexin with clavulanic acid.
A popular brand name under which a similar combination (amoxicillin/clavulanic acid) is marketed is Augmentin.
How It Works
Pharmacodynamics: Cefalexin, a first-generation cephalosporin, exerts its bactericidal effect by inhibiting bacterial cell wall synthesis. It binds to penicillin-binding proteins (PBPs), which are enzymes crucial for the final steps of peptidoglycan synthesis, a key component of the bacterial cell wall. Clavulanic acid, a beta-lactamase inhibitor, has little intrinsic antibacterial activity but binds and inactivates beta-lactamases produced by some bacteria. These beta-lactamases would otherwise degrade beta-lactam antibiotics like cefalexin, rendering them ineffective. The combination provides broader spectrum activity than cefalexin alone.
Pharmacokinetics: Cefalexin is acid-stable and well-absorbed orally, achieving peak plasma concentrations within one hour. Food does not significantly affect its absorption. It is widely distributed in body fluids, including bone, and achieves therapeutic concentrations in most tissues. Approximately 10% to 15% of cefalexin is protein-bound. Cefalexin does not undergo significant hepatic metabolism and is primarily excreted unchanged by the kidneys. Clavulanic acid is also well-absorbed orally. It undergoes extensive metabolism and is primarily excreted in the urine.
Elimination: Cefalexin is primarily eliminated via renal excretion, while clavulanic acid undergoes metabolism followed by renal excretion.
Dosage
Standard Dosage
Adults:
- Standard Dosage: Typically, 250 mg to 1 g every 6 to 12 hours. Dosages may be adjusted based on the severity and type of infection.
- Maximum Dosage: Up to 4 g per day.
Children:
- Standard Dosage: Dosage is weight-based: 25 to 100 mg/kg per day, divided into doses every 6, 8, or 12 hours, depending upon the severity of infection. Consult with a pharmacist to determine the correct volume of suspension for the prescribed dose, especially in children aged 6-12 years, where a twice-daily formulation is often preferred.
- Pediatric Considerations: Use with caution. Closely monitor infants for potential side effects, particularly diarrhea.
Special Cases:
- Elderly Patients: Dose adjustments may be necessary for elderly patients with reduced renal function.
- Patients with Renal Impairment: Dosage reduction is required for patients with moderate to severe renal impairment, with dosing frequency adjusted based on creatinine clearance.
- Patients with Hepatic Dysfunction: Caution advised; dosage adjustment may be necessary.
- Patients with Comorbid Conditions: Individualized dosing may be required based on specific comorbid conditions. For example, caution is warranted in patients with colitis or seizure disorders.
Clinical Use Cases
Dosage recommendations for specific medical settings are not well-defined for this specific combination. Dosing would be determined by the infection being treated and patient-specific factors.
Dosage Adjustments
Dose adjustments are necessary based on renal function, hepatic function, age, and the severity of the infection.
Side Effects
Common Side Effects:
Diarrhea, nausea, vomiting, indigestion, abdominal pain, skin rashes, urticaria, vaginitis, abdominal discomfort, flatulence, and headache.
Rare but Serious Side Effects:
Watery or bloody stools, stomach cramps, fever, severe vomiting, difficulty breathing or swallowing, swelling of the face, throat, tongue, lips, and eyes, wheezing, peeling, blistering, or shedding skin, return of fever, sore throat, chills, or other signs of infection, jaundice, cholestatic hepatitis (with prolonged use), easy bruising or bleeding, reversible hepatitis, allergic reactions (including anaphylaxis), bloody or prolonged diarrhea, and toxic epidermal necrolysis.
Long-Term Effects:
Chronic complications from prolonged use are rare but can include antibiotic-associated colitis and Clostridium difficile infection.
Adverse Drug Reactions (ADR):
Anaphylaxis, severe skin reactions (Stevens-Johnson syndrome, toxic epidermal necrolysis), Clostridium difficile-associated diarrhea, and drug-induced liver injury.
Contraindications
- Known allergy to cephalosporins or penicillins.
- History of hepatic disorders associated with previous use of clavulanic acid/amoxicillin combinations.
- Confirmed or suspected infectious mononucleosis.
Drug Interactions
- Antibiotics: Probenecid, other aminoglycosides, other cephalosporins.
- Anticoagulants: May potentiate the effects of warfarin.
- Metformin: Cefalexin can reduce metformin clearance.
- Diuretics: Furosemide can reduce cefalexin clearance.
- Alcohol: Avoid alcohol consumption as it may increase the risk of side effects or sensitivity to alcohol.
- Oral contraceptives: Cephalosporins may reduce the effectiveness of oral contraceptives.
Pregnancy and Breastfeeding
- Pregnancy: Generally considered safe; no evidence of fetal harm. However, always consult with a doctor before use during pregnancy.
- Breastfeeding: Small amounts are excreted in breast milk and may cause diarrhea in infants. Monitor infant for diarrhea, rash, or oral thrush. Consult with a doctor before using while breastfeeding.
Drug Profile Summary
- Mechanism of Action: Cefalexin inhibits bacterial cell wall synthesis; clavulanic acid inhibits beta-lactamase.
- Side Effects: Diarrhea, nausea, rash; rarely, anaphylaxis, C. difficile infection.
- Contraindications: Penicillin or cephalosporin allergy, history of hepatic disorders with clavulanic acid/amoxicillin.
- Drug Interactions: Probenecid, metformin, furosemide, alcohol.
- Pregnancy & Breastfeeding: Generally safe; monitor infant for side effects during breastfeeding.
- Dosage: Adults: 250mg-1g every 6-12 hours (up to 4g/day); Children: 25-100mg/kg/day divided every 6-12 hours.
- Monitoring Parameters: Renal function, liver function tests, signs of superinfection (e.g., thrush, C. difficile infection).
Frequently combined with other antibiotics (like metronidazole) for specific infections, offering synergistic effects.
Precautions
- Assess for penicillin or cephalosporin allergy.
- Evaluate renal and hepatic function before and during treatment.
- Monitor for signs of superinfection.
- Avoid alcohol.
- Caution in patients with a history of colitis or seizures.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Cefalexin + Clavulanic Acid?
A: Adults: 250mg-1g every 6-12 hours, up to 4g/day. Children: 25-100mg/kg/day, divided every 6, 8, or 12 hours based on severity. Adjustments are necessary for patients with renal or hepatic impairment.
Q2: What infections does this combination treat?
A: Bacterial infections of skin, respiratory tract, urinary tract, bone, ear (otitis media), among others, especially those caused by beta-lactamase producing organisms.
Q3: Is this combination safe during pregnancy and breastfeeding?
A: Generally considered safe during pregnancy. During breastfeeding, monitor the infant for adverse reactions. Consult with a doctor before use.
Q4: What are the most common side effects?
A: Diarrhea, nausea, vomiting, and skin rash.
Q5: What are the serious side effects to watch for?
A: Allergic reactions (including anaphylaxis), C. difficile infection, and liver dysfunction.
Q6: What are the contraindications for this combination?
A: Penicillin or cephalosporin allergy, history of hepatic disorders with clavulanic acid/amoxicillin.
Q7: What drug interactions are clinically significant?
A: Probenecid, metformin, furosemide, other antibiotics, and alcohol.
Q8: What are important monitoring parameters during therapy?
A: Monitor renal function, liver function tests, and signs of superinfection.
Q9: Can I take this medication with food?
A: Yes, Cefalexin can be taken with or without food. However, check the specific instructions given by your doctor or on your medication packaging.
Q10: What if I miss a dose?
A: Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one.
