Phenoxymethyl Penicillin (Penicillin V) is indicated for the treatment of mild to moderately severe bacterial infections caused by penicillin-susceptible organisms that respond to oral penicillin therapy. These include:

• Ear, nose, and throat infections, such as tonsillitis, pharyngitis, laryngitis, otitis media, and sinusitis
• Lower respiratory tract infections, such as bronchitis, pneumonia, and bronchopneumonia
• Infections caused by Group A beta-hemolytic streptococci, including scarlet fever, erysipelas, and rheumatic fever
• Skin infections, such as pyoderma, furunculosis, phlegmon, erysipeloid, and erythema migrans, when the causative organisms are sensitive to penicillin
• Bacterial lymphadenitis and lymphangitis
• Infections of the mouth, gums, or jaws, including inflammatory infiltrates, delayed dentition stages II and III, antral fistulae, and secondary bacterial infections caused by Gram-positive organisms following virus-induced gingivitis or stomatitis

Phenoxymethyl Penicillin is also used for the prophylaxis of scarlet fever and to help prevent recurrent rheumatic fever. It may also be used to prevent infection after dental procedures, oral surgery, or tooth extraction in certain high-risk patients, such as those with congenital heart defects, artificial heart valves, or rheumatic endocarditis. In some situations, it may be necessary to use it in combination with another appropriate antibiotic.

Phenoxymethyl Penicillin, also known as Penicillin V, is acid-stable and is absorbed from the upper part of the small intestine. Among its different forms, the potassium salt is absorbed most effectively. It may be taken with food, but maximum absorption is achieved when the medicine is taken orally at least 1 hour before or 2 hours after meals. Phenoxymethyl Penicillin provides a convenient option for the treatment of Gram-positive infections. Compared with Penicillin G, it has the clear advantage of being more resistant to inactivation by gastric acid.

The dosage of Phenoxymethyl penicillin should be determined according to the sensitivity of the causative microorganism and the severity of the infection, and adjusted to the clinical response of the patient.

Adults: 250-500 mg 6 hourly

Children (above 1 year):

• 125-250 mg 6 hourly
• 125 mg/5 ml powder for suspension: 1-2 teaspoonful (5-10 ml) 6 hourly
• 250 mg/5 ml powder for suspension: ½-1 teaspoonful (2.5-5 ml) 6 hourly

Infants (below 1 year):

• 62.5-125 mg 6 hourly.
• 125 mg/5 ml powder for suspension: ½-1 teaspoonful (2.5-5 ml) 6 hourly, or as prescribed by the physician.

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

Phenoxymethyl Penicillin is best taken on an empty stomach, preferably one hour before meals. The tablets are swallowed without chewing with sufficient amounts of liquid. Before each use of this syrup, the bottle has to be shaken vigorously.

Food interaction: Taking Phenoxymethyl Penicillin with food may reduce the rate of its absorption. Therefore, it is best taken on an empty stomach, preferably 1 hour before meals, to achieve optimal absorption.

Drug interactions:  Concomitant use of penicillins may increase serum methotrexate levels and enhance its toxic effects. For this reason, monitoring of methotrexate serum levels is recommended. If diarrhoea occurs during treatment with Phenoxymethyl Penicillin, the absorption of other orally administered medicines may be affected, which may reduce their effectiveness.

When penicillins are used together with bacteriostatic antibiotics or chemotherapeutic agents such as tetracyclines or chloramphenicol, the antibacterial effect of penicillins may be reduced or completely inhibited.

Concurrent use of probenecid decreases the renal excretion of penicillins. Likewise, indomethacin, phenylbutazone, salicylates, and sulfinpyrazone may increase and prolong serum levels of Phenoxymethyl Penicillin.

Administration of penicillins may also cause a temporary reduction in plasma oestrogen and gestagen concentrations. As a result, the effectiveness of oral contraceptives may become less reliable. The absorption of Phenoxymethyl Penicillin may also be reduced if intestinal sterilization with aminoglycosides such as neomycin has recently been performed or is still ongoing. Combined use of penicillins with oral anticoagulants such as warfarin may prolong prothrombin time/INR.

Interference with laboratory tests: Phenoxymethyl Penicillin may interfere with certain laboratory investigations. Non-enzymatic urine glucose tests and urobilinogen tests may produce false-positive results.

Phenoxymethyl Penicillin should not be used in patients with known hypersensitivity to penicillins or to any component of the formulation. It should also not be used in patients with severe gastrointestinal disorders associated with vomiting and diarrhoea, as these conditions may interfere with proper absorption of the medicine.

Phenoxymethyl Penicillin may occasionally cause hypersensitivity reactions, particularly affecting the skin, such as urticaria, morbilliform or scarlatiniform rash, itching, and eosinophilia. More serious allergic reactions may also occur, including drug fever, vasculitis, serum sickness, and interstitial nephritis. In rare cases, severe anaphylactic or anaphylactoid reactions may develop, with symptoms such as angioedema, laryngeal oedema, bronchospasm, and shock. If signs of such reactions appear, treatment must be stopped immediately.

Occasionally, skin rashes or inflammation of the mucous membranes, especially in the mouth (stomatitis), may occur. Dry mouth and taste disturbances have rarely been reported. In isolated cases, severe bullous skin reactions involving the mucous membranes have been reported, including Stevens-Johnson syndrome and Lyell’s syndrome.

Gastrointestinal side effects may include nausea, vomiting, abdominal pain, loose stools, and diarrhoea. Diarrhoea may sometimes be a sign of enterocolitis, which in some cases may be haemorrhagic. A specific antibiotic-associated form, pseudomembranous colitis—most commonly linked to Clostridium difficile—should be considered in patients who develop severe or persistent diarrhoea during treatment or in the first few weeks afterward. If this condition is suspected, Phenoxymethyl Penicillin should be discontinued immediately, and prompt medical treatment is required. Medicines that reduce intestinal movement should not be used in such cases.

In isolated cases, especially with high doses or prolonged treatment, changes in blood counts may occur, including reduced numbers of white blood cells (such as leucopenia, granulocytopenia, or agranulocytosis), red blood cells (for example due to haemolytic anaemia), platelets, or even pancytopenia and myelosuppression.

During treatment of spirochaetal infections, a Herxheimer reaction may occur, characterized by the appearance or worsening of symptoms such as fever, chills, headache, and joint pain.In rare cases, drug-induced aseptic meningitis has been reported. Very rarely, temporary tooth discoloration may occur during treatment.

Use of antibiotics, especially over a prolonged period, may also lead to overgrowth of resistant microorganisms. Like other beta-lactam antibiotics, Phenoxymethyl Penicillin may increase the risk of encephalopathy, which can include convulsions, confusion, reduced consciousness, and movement disorders, especially in cases of overdose or renal impairment.

Phenoxymethylpenicillin can cross the placenta and reach the unborn baby. When medically necessary, it may be used at any stage of pregnancy under a doctor’s supervision. Small amounts of the medicine can also pass into breast milk. It is generally considered safe during breastfeeding, but in some cases the infant may experience mild diarrhea or yeast infection in the mucous membranes.

Cross-allergy between penicillins and cephalosporins should be taken into account before using phenoxymethylpenicillin. In patients with heart disease or significant electrolyte imbalance, the potassium content of this medicine may need to be considered.

Beta-lactam antibiotics may increase the risk of encephalopathy, particularly in cases of overdose or in patients with kidney impairment. Symptoms may include seizures, confusion, reduced consciousness, or movement disorders.

Prolonged use of antibiotics can sometimes lead to the growth of resistant microorganisms. Therefore, the patient’s condition should be monitored regularly during treatment. If a secondary infection develops, suitable treatment should be provided. For patients with diabetes, the sugar content in phenoxymethylpenicillin syrup should also be considered. This medicine generally does not affect the ability to drive or operate machinery. However, if neurological side effects such as confusion, seizures, or decreased alertness occur, the patient should avoid driving or operating machines.

Phenoxymethylpenicillin generally has low toxicity and a wide therapeutic safety margin. Taking a single oral dose that is higher than the recommended amount usually does not cause serious acute toxicity. However, excessive use of beta-lactam antibiotics may increase the risk of encephalopathy, particularly in patients with kidney problems or when a large overdose occurs. In most cases of overdose, no special treatment is required other than stopping the medication. If necessary, phenoxymethylpenicillin can be removed from the body through haemodialysis.

Penicillin antibiotics, including Benzylpenicillin and Phenoxymethylpenicillin

Keep the medicine in a cool, dry place and protect it from direct light.