Penicillin V

Phenoxymethylpenicillin potassium.

Each tablet contains: Phenoxymethyl Penicillin Potassium equivalent to 125mg of Phenoxymethyl Penicillin.

Pharmacology: Phenoxymethylpenicillin is an antimicrobial acid derived from the growth of certain strains of Penicillum notatum. Its action may be bacteriostatic or bactericidal, depending on its concentration against most Gram-positive bacteria and Gram-negative cocci and against some spirochetes and actinomycetes. In adequately high concentrations at the site of action, it has a bactericidal effect caused by inhibition of the synthesis of the bacterial cell wall. It is more resistant to inactivation by gastric acid secretions and more slowly inactivated by penicillinase thus it is slightly more active than benzyl-pencinillin against some staphylococci, but is slightly less active against streptococci and much less active against Gram-negative micro-organisms including gonococci. Though it is more slowly inactivated by penicillinase, resistance of microorganisms to it is usually natural and is associated with insensitive organisms and those which produce penicillinase. Resistance is more common among staphylococci.
Phenoxymethylpenicillin is more stable in gastric acid secretions and is more completely absorbed than benzylpenicillin from G.I.T. following oral administration. Absorption is usually rapid, but peak serum concentrations may be variable. Peak serum concentrations of about 0.7μg per ml have been observed following a dose of 125 mg and 3 to 5 μg per ml following 250 to 500 mg. Absorption of phenoxymethylpenicillin appears to be reduced in subjects with celiac disease and appears to be more rapid in fasting state. Its half-life is about 30 minutes. Phenoxymethylpenicillin is widely distributed throughout the body and enters pleural, pericardial, ascitic and synovial fluids and also the cerebrospinal fluid when the meninges are inflamed.
It crosses the placenta and is also secreted in milk. About 50 to 80% of phenoxymethylpenicillin is bound to plasma proteins in the blood. Phenoxymethylpenicillin may be metabolised in the liver by hydroxylation. Excretion of phenoxymethylpenicillin is mainly renal where 20 to 35% of an oral dose is excreted in the urine in 24 hours. This renal excretion is delayed by probenecid. It is also excreted in small amounts in bile.

Disease which are caused by penicillin-susceptible organisms, such as angina tonsillaris, bacterial bronchitis, acute otitis media, acute sinusitis, scarlet fever, furuncles, abscesses: supportive therapy in bacterial pneumonia in as much as parenteral therapy is not necessary; infection or danger of infection by haemolytic streptococci for the prophylaxis of recurrences in rheumatic fever, polyarthritis, bacterial endocarditis, glomerulonephritis, particularly after tonsillectomy; prophylaxis against infection in stomatology (e.g, tooth extractions).

Usual Adult Dose: Oral, the equivalent of penicillin V: 125 to 500 mg (200,000 to 800,000 units) every six to eight hours.
Note: Continuous prophylaxis of streptococcal infections in patients with a history of rheumatic heart disease and/or chorea: Oral, the equivalent of penicillin V-125 to 250 mg (200,000 to 400,000 units) every twelve hours.
Usual Adult Prescribing Limits: The equivalent of Penicillin V- up to 7.2 gm.
Usual Paediatric Dose: Oral, the equivalent of Penicillin V- infant and children up to 12 years of age: 2.5 to 9.3 mg per kg body weight every 4 hours; 3.75 to 14 mg per kg body weight every 6 hours; 5.0 to 18.7 mg per kg body weight every 8 hours.

Overdosage Symptoms: Severe nausea and vomiting, confusion, drowsiness and myoclonus which may progress to convulsion. Large dose may also cause hyperkalemia.
Overdosage Treatment: Symptomatic and supportive.
Hemodialysis may aid in removing penicillins from the blood.
Symptoms of Hypersensitivity Reactions: Urticarial, joint pains, bronchospasm, angioneurotic oedema, circulatory failure and shock.
Treatment: At the first sign to an immediate reaction to penicillin treatment, 0.3 to 1 ml of Adrenaline Injection should be given intramuscularly (or in severe cases 0.2 ml well diluted intravenously) followed by a further dose if no improvement occurs. This should be followed by an antihistamine, such as diphenhydramine or chlorpheniramine given parenterally and a corticosteroid given intravenously. If bronchospasm is severe, aminophylline (250 mg in 10 ml) may be given intravenously. Assisted respiration is necessary if there is upper airway obstruction and plasma or suitable electrolyte solutions should be given intravenously if circulatory failure occurs. Urticaria and joint pains, if severe, may be treated with corticosteroids by mouth.

Known or suspected hypersensitivity to penicillins and/or cephalosporins.

Bactericidal penicillins should not be given in association with bacteriostatic antibiotics. On concurrent administration of antiphlogistics, antirheumatics and antipyretics one should bear in mind the competitive inhibition of excretion. Owing to the virtual atoxicity of penicillin. It is not necessary to reduce the dosage in renal insufficiency. Under certain circumstances penicillin can stimulate glycosuria when performing diagnostic blood sugar determinations. The physician should be consulted if side-effects occur.

Risk-benefit must be considered when Penicillin V is intended for use in pregnancy and during breast-feeding.

Penicillin V is well tolerated. Allergic reactions occur less frequently and runs a milder course than applying parenteral penicillin therapy.

Aspirin, Sulphamethoxypyridazine and Sulphaethidole inhibit the serum binding of phenoxymethyl penicillin. Chloroquine Phosphate diminishes the antibacterial action of phenoxymethyl penicillin.

Keep container tightly closed in a dry place, below 25°C; Protect from light.
Shelf-Life: 2 years from the date of manufacture.

Penicillins

J01CE02 - phenoxymethylpenicillin ; Belongs to the class of beta-lactamase sensitive penicillins. Used in the systemic treatment of infections.

B