Description

Phenoxymethyl penicillin or penicillin V is acid-stable and is absorbed from the upper part of the small intestine. Of different forms of Phenoxymethyl penicillin, the potassium salt of Phenoxymethyl penicillin is best absorbed. This may be given with meals but maximum absorption is achieved when drug is administered orally at least 1 hour before or 2 hours after the meal. Phenoxymethyl penicillin offers a very convenient means of treating Grampositive infections. Phenoxymethyl penicillin has the distinct advantage over penicillin G in resistance to inactivation by gastric acid.

For the treatment of mild to moderately severe bacterial infections, if these are due to penicillin susceptible pathogens and respond to therapy with oral penicillin, such as: infections of the ear, nose and throat regions, e.g., tonsillitis, pharyngitis, laryngitis, otitis media, sinusitis. infections of the lower respiratory tract, e.g., bronchitis and pneumonia, bronchopneumonia. infections due to beta-hemolytic streptococci of group A, e.g., scarlet fever, erysipelas, rheumatic fever. skin infections, e.g., pyodermia, furunculosis, phlegmon, erysipeloid, erythema migrans, insofar as the micro-organisms are penicillin-susceptible. lymphadenitis and lymphangitis of bacterial origin. infections of the buccal cavity, gums or jaws, e.g., inflammatory infiltrates, delayed dentition stages II and III, antral fistulae, secondary bacterial infection with Gram-positive pathogens following virus-induced gingivitis or stomatitis. For prophylaxis of scarlet fever; also to prevent recurrences of rheumatic fever. For prophylaxis of infection after dental and oral surgical procedures or dental extractions in certain high risk patients (e.g. with congenital cardiac defects, artificial heart valves, rheumatic endocarditis). In some cases, combination with another appropriate antibiotic may be indicated.

Food: Concurrent intake of food leads to a reduction in the rate of absorption. Therefore, Phenoxymethyl penicillin is best taken on an empty stomach, preferably one hour before meals, in order to reach the highest possible rate of absorption. Drug interactions: Concomitant administration of penicillins may lead to increased levels of methotrexate in serum and potentiate its toxic effects. Monitoring of methotrexate serum levels is therefore necessary. If diarrhoea occurs as a consequence of treatment with Phenoxymethyl penicillin, the absorption of other orally administered drugs may be disturbed and their effcacy may consequently be impaired. If penicillins are combined with bacteriostatic chemotherapeutics or antibiotics (e.g., tetracyclines, chloramphenicol), the activity of penicillins may be attenuated or abolished. Concurrent administration of probenecid inhibits the renal excretion of penicillins. Concurrent use of indomethacin, phenylbutazone, salicylates or sulfinpyrazone may cause elevated and prolonged serum levels of phenoxymethylpenicillin. Administration of penicillins may cause a transient reduction in plasma concentrations of oestrogens and gestagens. The effectiveness of oral contraceptives is therefore uncertain. The absorption of Phenoxymethyl penicillin may be reduced where intestinal sterilization with aminoglycosides (e.g. neomycin) has just been performed or is still in progress. Combined use of penicillins and oral anticoagulants (e.g. warfarin) may prolong prothrombin time/INR. Interference with laboratory and diagnostic tests: Non-enzymatic urine glucose determinations and tests for urobilinogen may give false-positive results.

Phenoxymethyl Penicillin must not be administered in patients with hypersensitivity to penicillins or any of the excipients of this. Phenoxymethyl Penicillin must not be used to treat patients with severe gastrointestinal disorders accompanied by vomiting and diarrhea.

Occasionally, hypersensitivity reactions involving the skin (e.g. urticaria, morbilliform or scarlatiniform rashes, pruritus), eosinophilia or more serious allergic reactions, e.g. drug fever, vasculitis, serum sickness or interstitial nephritis, may develop. Anaphylactic or anaphylactoid reactions accompanied by, e.g- angioneurotic oedema, oedema of the larynx, bronchial spasm and shock may occur. In the event of signs pointing to anaphylactic/anaphylactoid reactions, the treatment must be terminated immediately. In occasional instances, there may be skin rashes or inflammation of mucous membranes, especially in the region of the mouth (stomatitis); dryness of the mouth and disorders of taste may rarely occur. The occurrence of severe bullous skin reactions- usually involving the mucosae- has been reported in isolated cases (Stevens-Johnson syndrome, Lyell's syndrome). Gastrointestinal disturbances with, e.g., nausea, vomiting, abdominal pain, loose stools, or diarrhoea may develop. Diarrhoea may sometimes be a symptom of enterocolitis which may, in some cases, be haemorrhagic. A particular form of enterocolitis that can occur with antibiotics is pseudomembranous colitis (in most cases due to Clostridium diffcile). This must be considered in patients in whom severe, persistent diarrhoea occurs during treatment or in the initial weeks thereafter. Even if pseudomembranous colitis is only suspected, administration of Phenoxymethyl penicillin must be halted immediately. This type of colitis requires immediate and appropriate treatment by a physician. Drugs that inhibit intestinal peristalsis must not be taken in such cases. In isolated cases, particularly after high doses and prolonged administration, changes in blood picture such as reduction in the number of white blood cells (e.g.,leucopenia, granulocytopenia, agranulocytosis), erythrocytes (e.g., due to haemolytic anaemia), thrombocytes, or pancytopenia and myelosuppression may occur. During treatment for spirochaetal infections, Herxheimer's reaction characterized by the occurrence or worsening of general symptoms such as fever, chills, headache, and joint pains may develop. In isolated cases, drug-induced aseptic meningitis may occur. In extremely rare cases, transient discolouration of the teeth may be seen during treatment with Phenoxymethyl penicillin. Administration of antibiotics, especially if prolonged, may lead to the proliferation of resistant micro organisms. Beta-lactams predispose the patient to encephalopathy risk (which may include convulsions, confusion, impairment of consciousness, movement disorders), particularly in case of overdose or renal impairment.

Phenoxymethylpenicillin crosses the placenta. Given the appropriate indication, this may be used at any time throughout pregnancy. Phenoxymethylpenicillin passes into the breast milk in small amounts. This may be used during lactation; however, diarrhoea and yeast colonization of mucous membranes may occur in the infant.