Amoxicillin

Generic name: Amoxicillin Trihydrate Trade names: Amoxil, Moxilen, Ospamox, Trimox, Wymox Drug class: Aminopenicillin antibiotic Dosages: 250 mg, 500 mg, 875 mg tablets Amoxicillin combinations: Generic name: Amoxicillin/clavulanic acid Trade names: Augmentin, Co-Amoxiclav, Clavamox Drug class: Penicillin antibiotic/Beta-lactamase inhibitor

Amoxicillin Uses

Amoxicillin is an aminopenicillin antibiotic. It destroys the outer wall of pathogenic bacteria, thereby killing the bacteria but not harming our body's cells. Amoxicillin is used to treat strep throat, tonsillopharyngitis, ear infections (otitis media), sinusitis, bronchitis, infected bite wounds, dental abscess.

Amoxicillin clavulanate (Co-amoxiclav) is a combination of the antibiotic amoxicillin and β-lactamase inhibitor clavulanic acid. This combination provides increased spectrum of activity against amoxicillin-resistant bacteria that produce β-lactamase.

Many prescribers are using amoxicillin clavulanate because they feel amoxicillin is no longer effective. The risk of liver toxicity is about 6 times greater with amoxicillin-clavulanate than with amoxicillin alone.

Amoxicillin for Strep Throat (Streptococcal Pharyngitis)

Strep throat (group A Streptococcal pharyngitis) is most common in children between the ages of 5 and 15, but it affects people of all ages. Group A beta-hemolytic streptococcus (GABHS), the bacteria that cause strep throat, respond quickly to antibiotics, and treatment stops the infection from spreading to other people. Amoxicillin is frequently prescribed for treating strep throat and prevent complications of strep throat such as poststreptococcal glomerulonephritis, rheumatic fever, peritonsillar abscess.

Amoxicillin dosage:

Adults: 500 mg 3 times daily for 10 days.

Children: 40-50 mg/kg/day, divided into 3 doses for 10 days.

The cure rates for amoxicillin exceed 80% [2]. Most GABHS isolates have not developed resistance to penicillins.

How to distinguish Sore throat from Strep?

So, what is the difference between a sore throat, "strep", tonsillitis, and pharyngitis?

Pharyngitis is an inflammation of the pharynx. Tonsillitis is an inflammation of the pharyngeal tonsils (adenoids). Both terms may be used interchangeably.

Both pharyngitis and tonsillitis are commonly called a sore throat. Most cases of sore throat are caused by a viral illnesses.

Strep throat is a tonsillopharyngeal infection (such as tonsillitis or pharyngitis) caused by Group A beta hemolytic streptococci. Group A streptococci cause about 15-30% of acute sore throats in children.

Here are some clues to help you distinguish strep throat:

• Predominant severe sore throat.
• Red, inflamed, swollen tonsils and pharynx.
• White patches or pus on the tonsils.
• Temperature higher than 38.5° C (101.3° F).
• Swollen lymph nodes on the neck.
• Strep throat usually does not cause multiple symptoms such as runny nose, cough, congestion, and diarrhea. However, abdominal pain and vomiting sometimes present.
• A sandpaper-like rash on the trunk is a sign of scarlet fever.

Amoxicillin vs Penicillin

Amoxicillin is able to withstand stomach acid better, releasing more antibiotic into the blood stream. Amoxicillin has a longer half-life than penicillin, thus allowing less frequent dosing. Amoxicillin, compared to penicillin, kills a wider range of bacteria.

The cure rates for amoxicillin are similar to those for penicillin V in treatment of strep throat. Some clinical trials have demonstrated that amoxicillin works a bit better [1].

Amoxicillin suspensions taste better than penicillin V suspensions, and may be taken with food. However, diarrhea and skin rash are more common with amoxicillin.

For more than 40 years, penicillin has been the mainstay for treating strep throat. The American Academy of Family Physicians, the AAFP, the Centers for Disease Control and Prevention, and other organizations still recommend penicillin as the first line choice for streptococcal pharyngitis [2].

Amoxicillin vs Augmentin

The addition of clavulanic acid (beta-lactamase inhibitor) to the amoxicillin improves the effectiveness of amoxicillin against beta-lactamase producing organisms, e.g. Staphylococcus aureus, H. influenzae.

Some medical authorities consider Augmentin has a place in the treatment of middle ear infections after amoxicillin has been tried and failed.

Amoxicillin vs Ampicillin

Amoxicillin and ampicillin are similar in chemical structure and antimicrobial activity spectrum. The main differences lie in the drug absorption from the gastrointestinal tract.

Amoxicillin has replaced oral ampicillin for all infections because amoxicillin yields higher and more prolonged blood and tissue levels as compared to equivalent doses of ampicillin. One exception is in the treatment of bacillary dysentery (shigellosis) where amoxicillin is less effective.

Amoxicillin is better absorbed than ampicillin when taken by mouth, and unlike ampicillin, its absorption is not affected by food.

Other amoxicillin alternatives: bacampicillin, flucloxacillin, dicloxacillin.

• 1. Curtin-Wirt C, Casey JR, Murray PC, Cleary CT, Hoeger WJ, Marsocci SM, Murphy ML, Francis AB, Pichichero ME. Efficacy of penicillin vs. amoxicillin in children with group A beta hemolytic streptococcal tonsillopharyngitis. Clin Pediatr (Phila). 2003 Apr;42(3):219-25.
• 2. Choby BA. Diagnosis and Treatment of Streptococcal Pharyngitis Am Fam Physician. 2009 Mar 1;79(5):383-90.