AMOXICILLIN AND CLAVULANATE POTASSIUM

AMOXICILLIN AND CLAVULANATE POTASSIUM
(a-mox-i-sill'in)
Augmentin, Augmentin-ES600, Augmentin XR, Clavulin

Classifications: beta-lactam antibiotic; aminopenicillin;
Therapeutic: antibiotic
Prototype: Ampicillin
Pregnancy Category: B

Availability

250 mg, 500 mg, 875 mg tablets; 125 mg, 200 mg, 400 mg chewable tablets; 125 mg/5 mL, 200 mg/5 mL, 250 mg/5 mL, 400 mg/5 mL, 600 mg/5 mL oral suspension; 1000 mg amoxicillin/62.5 mg clavulanate sustained-release tablets

Action

As a beta-lactam antibiotic, amoxicillin is bactericidal. It inhibits the final stage of bacterial cell wall synthesis by binding with specific penicillin-binding proteins (PBPs) that are located inside the bacterial cell wall that leads to bacterial cell lysis and death.

Therapeutic Effect

Effectivenes of ampicillin is synergistic in combination with clavulanic acid. Clavulanic acid in combination with ampicillin inhibits enzyme (beta-lactamase) degradation of amoxicillin and by synergism extends both spectrum of activity and bactericidal effect of amoxicillin against many strains of beta-lactamase-producing bacteria resistant to amoxicillin alone.

Uses

Infections caused by susceptible beta-lactamase-producing organisms: lower respiratory tract infections, acute bacterial sinusitis, community acquired pneumonia, otitis media, sinusitis, skin and skin structure infections, and UTI.

Contraindications

Hypersensitivity to penicillins; infectious mononucleosis; patient with previous history of drug-induced cholestasis, jaundice, or other hepatic dysfunction.

Cautious Use

Allergic disorders; cephalosporin hypersensitivity; GI disorders; hepatic or renal disease; elderly; pregnancy (category B), lactation.

Route & Dosage

Mild to Moderate Infections
Adult: PO 250 or 500 mg tablet (each with 125 mg clavulanic acid) q8–12h; Sustained-release tabs: 2 tablets (2000 mg amoxicillin/125 mg clavulanate) q12h x 7–10 d
Child: PO <40 kg, 20–40 mg/kg/d (based on amoxicillin component) divided q8–12h; >3 mo, 90 mg/kg/d of 600 ES divided q12h x 10 d
Neonate/Infant (<3 mo): PO 30 mg/kg/d (amoxicillin) divided q12h

Administration

Oral

Give at the start of a meal to minimize GI upset and enhance absorption.
Note that both 250- and 500-mg tablets contain the exact amount of clavulanic acid (125 mg and potassium salt); therefore, two 250-mg tablets are not equivalent to one 500-mg tablet.
Reconstitute oral suspension by adding amount of water specified on container to provide a 5 mL suspension. Tap bottle before adding water to loosen powder, then add water in 2 portions, agitating suspension well before each addition.
Agitate suspension well just before administration of each dose.
Give dialysis patient an additional 2 doses on the day of dialysis; one dose before and another dose after dialysis.
Store tablets in tight containers at <24° C (71° F). Reconstituted oral suspension should be refrigerated at 2°–8° C (36°–46° F), then discarded after 10 d.

Adverse Effects (≥1%)

GI: Diarrhea, nausea, vomiting. Skin: Rash, urticaria. Other: Candidal vaginitis; moderate increases in serum ALT, AST; glomerulonephritis; agranulocytosis (rare).

Diagnostic Test Interference

May interfere with urinary glucose determinations using cupric sulfate, Benedict's solution, Clinitest; does not affect glucose oxidase methods (e.g., Clinistix, TesTape). Positive direct antiglobulin (Coombs') test results may be reported, a reaction that could interfere with hematologic studies or with transfusion cross-matching procedures.

Interactions

Drug: tetracyclines may inhibit activity of amoxicillin; probenecid prolongs the activity of amoxicillin.

Pharmacokinetics

Absorption: Nearly complete absorption. Peak: 1–2 h. Distribution: Diffuses into most tissues and body fluids, except synovial fluid and CSF (unless meninges are inflamed); crosses placenta; distributed into breast milk in very small amounts. Metabolism: In liver. Elimination: 50–73% of the amoxicillin and 25–45% of the clavulanate dose excreted in urine in 2 h. Half-Life: Amoxicillin 1–1.3 h, clavulanate 0.78–1.2 h.

Nursing Implications

Assessment & Drug Effects

Determine previous hypersensitivity reactions to penicillins, cephalosporins, and other allergens prior to therapy.
Lab tests: Baseline C&S tests prior to initiation of therapy; start drug pending results.
Monitor for S&S of an urticarial rash (usually occurring within a few days after start of drug) suggestive of a hypersensitivity reaction. If it occurs, look for other signs of hypersensitivity (fever, wheezing, generalized itching, dyspnea), and report to physician immediately.
Note: Generalized, erythematous, maculopapular rash (ampicillin rash) is not due to hypersensitivity. It is usually mild, but can be severe. Report onset of rash to physician, since hypersensitivity should be ruled out.

Patient & Family Education

Female patients should report onset of symptoms of Candidal vaginitis (e.g., moderate amount of white, cheesy, nonodorous vaginal discharge; vaginal inflammation and itching; vulvar excoriation, inflammation, burning, itching). Therapy may have to be discontinued.
Note: Use Clinistix or TesTape when monitoring urinary glucose to avoid false readings with diabetes mellitus.

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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