Amoxicillin

Some clinicians select amoxicillin over penicillin VK to treat odontogenic infection because of a more convenient dosing regimen e.g., 2-3 doses daily for amoxicillin versus 4 doses daily for penicillin VK. Except for coverage of Haemophilus influenzae in acute sinus and otitis media infections, amoxicillin is not any more effective than penicillin VK for the treatment of odontogenic infections. It is less effective than penicillin VK against aerobic gram-positive cocci and similar in efficacy against anaerobes. Thus penicillin VK is the drug of choice for treating odontogenic infections.

Contraindications: Hypersensitivity to amoxicillin, penicillin or any component of the formulation.

Warnings/Precautions: Use with caution in patients with severe renal impairment (modify dosage); low incidence of cross-allergy with other beta-lactams and cephalosporins exists.

The usual daily oral dose for treating odontogenic infections in children is:

Children under 12 years: 20-40 mg/kg divided in 2-3 doses daily for 10 days.
Children over 12 years and adults: 250-500 mg 3 times/day, maximum 2-3 gm/day for 10 days.
Amoxicillin is supplied as a 125, 200, 250, 400 mg/5 ml solution or chewable tablets; 250 or 500 mg capsules.

Sample amoxicillin prescription for a 3-year-old patient weighing 12 kg (25 lb) with facial swelling:

Rx: Amoxicillin 125 mg/5 ml
Disp: 150 ml
Sig: Take 1 teaspoon every 8 hours for 10 days

In situations when amoxicillin is ineffective due to possible bacterial resistance to the drug and the patient cannot tolerate the adverse gastrointestinal side effects of clindamycin, clavulanate potassium can be administered in conjunction with amoxicillin (Augmentin®). Clavulonic acid binds and inhibits beta-lactamases that inactivate amoxicillin. It is recommended to be taken with food to increase absorption and decrease GI intolerance.

Contraindications: Hypersensitivity to amoxicillin, clavulanic acid, penicillin or any component of the formulation; history of hepatic dysfunction.

Warnings/Precautions: Prolonged use may result in superinfection. Use with caution in patients with severe renal impairment (modify dosage). Incidence of diarrhea is higher than with amoxicillin alone.

The usual daily oral dose of Augmentin® for treating odontogenic infections in children is:

Children ≥ 3 months and < 40 kg: 20-40 mg/kg/day in 3 divided doses.
Children > 40 kg and adults: 250-500 mg every 8 hours or 875 mg every 12 hours.
Augmentin® is supplied as 125, 200, 250, 400 mg /5ml solution, chewable tablets and tablets.

Sample amoxicillin/clavulanate (Augmentin®) prescription for a 3-year-old patient weighing 12 kg (25 lb) with facial swelling:

Rx: Augmentin® 125 mg/5 ml solution (or chewable tablets)
Disp: 150 ml (or 30 chewable tablets)
Sig: 1 tsp (or tablet) every 8 hours for 10 days