Amoxicillin Tri Hydrate

amoxicillin trihydrate (a mox i sill' in) Amoxil, Amoxil Pediatric Drops, Apo-Amoxi (CAN), DisperMox, Novamoxin (CAN), Nu-Amoxi (CAN), Trimox Pregnancy Category B Drug class

Antibiotic (penicillin–ampicillin type) Therapeutic actions

Bactericidal: Inhibits synthesis of cell wall of sensitive organisms, causing cell death. Indications

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Infections due to susceptible strains of Haemophilus influenzae, Escherichia coli, Proteus mirabilis, Neisseria gonorrhoeae, Streptococcus pneumoniae, Enterococcus faecalis, streptococci, nonpenicillinase-producing staphylococci Helicobacter pylori infection in combination with other agents Post-exposure prophylaxis against Bacillus anthracis Unlabeled use: Chlamydia trachomatis in pregnancy

Contraindications and cautions

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Contraindicated with allergies to penicillins, cephalosporins, or other allergens. Use cautiously with renal disorders, lactation.

Available forms

Chewable tablets—125, 200, 250, 400 mg; tablets—500, 875 mg; capsules—250, 500 mg; powder for oral suspension—50 mg/mL; 125 mg/5 mL, 200 mg/5 mL, 250 mg/5 mL, 400 mg/5 mL; tablets for oral suspension—200, 400 mg Available in oral preparations only. Dosages ADULTS AND PEDIATRIC PATIENTS > 40 KG

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URIs, GU infections, skin and soft-tissue infections: 250–500 mg PO q 8 hr or 875 mg PO bid. Post-exposure anthrax prophylaxis: 500 mg PO tid. Lower respiratory infections: 500 mg PO q 8 hr or 875 mg PO bid. Uncomplicated gonococcal infections: 3 g amoxicillin with 1 g probenecid PO. C. trachomatis in pregnancy: 500 mg PO tid for 7 days or 875 mg PO bid. Prevention of SBE in dental, oral, or upper respiratory procedures: 2 g 1 hr before procedure. Prevention of SBE in GI or GU procedures: 2 g ampicillin plus 1.5 mg/kg gentamicin IM or IV 30 min before procedure, followed by 1 g amoxicillin; for low-risk patients, 2 g 1 hr before procedure.

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H. pylori: 1 g bid with clarithromycin 500 mg bid and lansoprazole 30 mg bid for 14 days.

PEDIATRIC PATIENTS < 40 KG

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URIs, GU infections, skin, and soft-tissue infections: 20–40 mg/kg/day PO in divided doses q 8 hr. Post-exposure anthrax prophylaxis: 80 mg/kg/day PO divided into 3 doses. Prevention of SBE: Dental, oral, or upper respiratory procedures: 50 mg/kg 1 hr before procedure. Prevention of SBE in GI or GU procedures: 50 mg/kg ampicillin plus 2 mg/kg gentamicin IM or IV 30 min before procedure followed by 25 mg/kg amoxicillin. For moderate-risk patients, 50 mg/kg PO 1 hr before procedure.

PEDIATRIC PATIENTS

< 12 wk: Up to 30 mg/kg daily in divided doses q 12 hr. > 3 mo: • Mild to moderate URIs, GU infections, and skin infections: 20 mg/kg daily in divided doses q 8 hr or 25 mg/kg in divided doses q 12 hr. • For lower respiratory infections, or severe URIs, GU, or skin infections: 40 mg/kg daily in divided doses q 8 hr or 45 mg/kg daily in divided doses q 12 hr. Pharmacokinetics Route Oral

Onset Varies

Peak 1 hr

Duration 6–8 hr

Metabolism: T1/2: 1–1.4 hr Distribution: Crosses placenta; enters breast milk Excretion: Unchanged in the urine Adverse effects

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CNS: Lethargy, hallucinations, seizures GI: Glossitis, stomatitis, gastritis, sore mouth, furry tongue, black "hairy" tongue, nausea, vomiting, diarrhea, abdominal pain, bloody diarrhea, enterocolitis, pseudomembranous colitis, nonspecific hepatitis GU: Nephritis Hematologic: Anemia, thrombocytopenia, leukopenia, neutropenia, prolonged bleeding time Hypersensitivity: Rash, fever, wheezing, anaphylaxis Other: Superinfections—oral and rectal moniliasis, vaginitis

Interactions

Drug-drug • Increased effect with probenecid • Decreased effectiveness with tetracyclines, chloramphenicol • Decreased efficacy of hormonal contraceptives Drug-food • Delayed or reduced GI absorption with food

Nursing considerations Assessment

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History: Allergies to penicillins, cephalosporins, or other allergens; renal disorders; lactation Physical: Culture infected area; skin color, lesion; R, adventitious sounds; bowel sounds; CBC, liver and renal function tests, serum electrolytes, Hct, urinalysis

Interventions

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Culture infected area prior to treatment; reculture area if response is not as expected. Give in oral preparations only; absorption may be affected by presence of food; drug should be taken 1 hr before or 2 hr after meals. Continue therapy for at least 2 days after signs of infection have disappeared; continuation for 10 full days is recommended. Use corticosteroids, antihistamines for skin reactions.

Teaching points

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Take this drug around-the-clock. The drug should be taken on an empty stomach, 1 hr before or 2 hr after meals. Take the full course of therapy; do not stop because you feel better. This antibiotic is specific for this problem and should not be used to self-treat other infections. These side effects may occur: Nausea, vomiting, GI upset (eat small, frequent meals); diarrhea; sore mouth (perform frequent mouth care). Report unusual bleeding or bruising, sore throat, fever, rash, hives, severe diarrhea, difficulty breathing.

Adverse effects in Italic are most common; those in Bold are life-threatening.