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# Mega-CV (Amoxicillin/Potassium Clavulanate)
## Overview
Mega-CV is a fixed-dose combination antibiotic consisting of amoxicillin (a beta-lactam) and potassium clavulanate (a beta-lactamase inhibitor). The addition of clavulanate extends the spectrum of amoxicillin to include beta-lactamase-producing bacteria.
## Primary Indications
* Acute bacterial rhinosinusitis
* Community-acquired pneumonia
* Lower respiratory tract infections
* Otitis media
* Skin and skin structure infections
* Urinary tract infections
## Adult Dosing
Standard dosing for mild-moderate infection: 500 mg/125 mg orally every 8 or 12 hours.
For severe infections/respiratory infections: 875 mg/125 mg orally every 12 hours OR 2000 mg/125 mg (extended-release) every 12 hours.
*Note: Maximum daily dose of clavulanate should not exceed 375 mg to limit GI toxicity.*
## Pediatric Dosing
Dosing is based on the amoxicillin component.
* **Standard dose:** 20–45 mg/kg/day divided every 8–12 hours.
* **Recurrent/Resistant Otitis Media:** 90 mg/kg/day divided every 12 hours.
* *Note: Always use specific concentrations (e.g., 200 mg/5 mL vs 400 mg/5 mL) to ensure the correct ratio of amoxicillin to clavulanate.*
## Dose Adjustments
* **Renal Impairment:** Reduce frequency or dose based on creatinine clearance (CrCl).
* **CrCl <30 mL/min:** 875 mg tablet is contraindicated.
* **Hemodialysis:** Requires supplemental dosing. Consult local institutional protocol or renal dosing guidelines.
## Contraindications
* Known hypersensitivity to amoxicillin, clavulanate, or any penicillin.
* History of cholestatic jaundice or hepatic dysfunction associated with amoxicillin/clavulanate therapy.
## Adverse Effects
* **Common:** Diarrhea (frequently related to clavulanate content), nausea, vomiting, skin rash.
* **Serious:** Anaphylaxis, Clostridioides difficile-associated diarrhea, drug-induced hepatitis, Stevens-Johnson syndrome.
## Key Drug Interactions
* **Warfarin:** May increase INR and risk of bleeding due to alteration of gut flora.
* **Methotrexate:** May decrease renal clearance of methotrexate, increasing risk of toxicity.
* **Probenecid:** Decreases renal excretion of amoxicillin, increasing serum levels.
* **Oral Contraceptives:** May reduce efficacy; backup contraception is recommended.
## Monitoring
* Baseline and periodic hepatic function tests (LFTs) during prolonged therapy.
* Renal function (BUN/SCr).
* Monitor for signs of hypersensitivity (rash, urticaria, wheezing).
* Assess for presence of diarrhea (monitor for *C. difficile* symptoms).
## Clinical Pearls
* **Administration:** Take with a meal or snack to minimize gastrointestinal upset.
* **Ratio:** Different formulations have different amoxicillin-to-clavulanate ratios. Do not substitute 875 mg tablets for two 250 mg tablets, as the clavulanate content will differ.
* **Suspension:** Shake well before use. Reconstituted suspension must be stored in the refrigerator and discarded after 10 days.
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*Disclaimer: This information is for educational purposes and does not replace professional clinical judgment. Always verify dosages, contraindications, and drug interactions using current internal institutional protocols and the manufacturer's official prescribing information (package insert) before prescribing or administering medication.*
