Indications

Phenoxymethyl Penicillin is indicated in the treatment of mild to moderate revere infections caused by susceptible organisms which are mostly Gram-positive. The following infections usually respond to adequate dosage of Phenoxymethyl Penicillin.

Streptococcal infections (without bacteremia): mild to moderately sever infections of upper respiratory tract scarlet fever, mid erysipelas. Bacterial endocarditis due to L-Haemolytic streptococci (combined with streptomycin), lobar pneumonia, infections due to non-penicillinase producing staphylococci Pneumococci infections Acute otitis medie, Meningococci infections Fusospirochetosis vincent’s gingivitis and pharyngitis.

Prophylaxis: Prevention of recurrence following rheumatic fever and chorea. Puerperal sepsis, Diphtheria, Anthrax Gonococcal infections, Syphilis and yaws, Actinomycosis.

Therapeutic Class

Benzylpenicillin & Phenoxymethyl penicillin

Pharmacology

Phenoxymethyl Penicillin inhibits the final cross-linking stage of peptidoglycan production through binding and inactivation of transpeptidases on the inner surface of the bacterial cell membrane, thus inhibiting bacterial cell wall synthesis.

By binding to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall, Phenoxymethyl Penicillin inhibits the third and last stage of bacterial cell wall synthesis. Cell lysis is then mediated by bacterial cell wall autolytic enzymes such as autolysins; it is possible that Phenoxymethyl Penicillin interferes with an autolysin inhibitor.

It may be less active against some susceptible organisms, particularly gm-ve bacteria. It is suitable for mild to moderate infections.

Dosage

The dosge of Phenoxymethyl Penicillin should be determded accoedgto the snsitivityof the raustive mnro-orgnism and tie severity of tie infection, and adjusted to the clinical respons of the patient

Adults: 250-500 mg 6 hourly

Children: 125-250 mg 6 hourly

125 mg/5 ml Syrup: 1 to 2 teaspoonful (5-10 ml) 6 homiy

250 mg/5 ml Syrup: ½ to 1 teaspoonful (2.5-5 ml) 6 hourly

Infants: 62.5 -125 mg 6 hourly

125 mg/5 ml Syrup: ½ to 1 tea spoonful (2.5-5 ml) 6 hourly, or as prescribed by the physician.

Phenoxymethyl Penicillin is best taken with a empty stomach, preferably at least 1 hour before or 2 hour after meal.

Administration

Should be taken on an empty stomach. Take 1 hr before or 2 hr after meals.

Interaction

Reduced absorption with neomycin. May interfere with anticoagulant control. Antagonism of bactericidal effect by chloramphenicol, erythromycin and tetracyclines. May increase toxicity of methotrexate. May reduce the efficacy of OC. Reduced excretion with probenecid and sulfinpyrazone. May inactivate oral typhoid vaccine if ingested concomitantly.

Contraindications

It is contraindicated in patients known to be hypersensitive to penicillin. It is also contraindicated in severe acute infections.

Side Effects

Common encountered untoward effects include nausea, vomiting, epigastric distress& diarrhoea. The hypersensitivity reactions reported are skin eruptions urticara ad other serum sickness reactions, laryngeal oedema and aaphylaxis.

Pregnancy & Lactation

There are no contraidications to the ues of penicmin in pregnancy. Phenoxymethyl pencillin is excreted in the breast milk, which might cause allergic reaction to the infants.

Precautions & Warnings

Patient with history of asthma, seizure disorders, history of β-lactam allergy. Severe renal impairment. Pregnancy and lactation.

Overdose Effects

Symptoms: Nausea, vomiting, stomach pain, diarrhoea, and rarely, major motor seizures. If other symptoms are present, consider the possibility of an allergic reaction. Hyperkalaemia may result, particularly for patients with renal insufficiency.

Management: Symptomatic and supportive treatment. May admin activated charcoal with a cathartic, e.g. sorbitol to hasten drug elimination. May be removed by haemodialysis.

Reconstitution

Powder for oral solution: Add the amount of water specified on the bottle to provide a solution containing 125 mg or 250 mg per 5 ml. The water should be added to the powder in 2 portions and the solution agitated vigorously immediately after each addition.

Storage Conditions

Tablet or Powder for Oral Solution: Store between 20-25°C.

Reconstituted oral Solution: Store between 2-8°C. Protect from light.