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Penicillin V, Penicillin V Potassium

Penicillin V is a natural penicillin antibiotic.

Uses

Penicillin V potassium is used for the treatment of mild to moderately severe infections caused by organisms susceptible to low concentrations of the drug or for prophylaxis of certain streptococcal infections. For specific information on the uses of penicillin V potassium, see Uses in the Natural Penicillins General Statement 8:12.16.04.

Dosage and Administration

Reconstitution and Administration

Penicillin V potassium is administered orally. Penicillin V potassium should not be used for the initial treatment of severe infections and should not be relied on in patients with nausea, vomiting, gastric dilatation, esophageal achalasia, or intestinal hypermotility. Although penicillin V potassium may be given with meals, maximum absorption is achieved when the drug is administered orally at least 1 hour before or 2 hours after meals. Penicillin V potassium powder for oral solution should be reconstituted at the time of dispensing by adding the amount of water specified on the bottle to provide a solution containing 125 or 250 mg of penicillin V per 5 mL. The water should be added to the powder for oral solution in 2 portions and the solution agitated vigorously immediately after each addition.

Dosage

Dosage of penicillin V potassium is expressed in terms of penicillin V. Although dosage of the drug is usually expressed in terms of weight, it may be expressed in terms of USP penicillin V units. Generally, 250 mg of penicillin V is considered equivalent to 400,000 units of the drug. (See Chemistry and Stability: Chemistry.)

Pediatric Dosage

Children 12 years of age or older may receive the usual adult dosage of penicillin V. Dosage of the drug for children younger than 12 years of age should generally be based on weight. The usual daily dosage of penicillin V for the treatment of infections in children older than 1 month of age is 15-62.5 mg/kg (25,000-100,000 units/kg) daily given in 3-6 divided doses; alternatively, a dosage of 0.5-1 g/m2 daily, given in divided doses, has been used.

Staphylococcal and Streptococcal Infections

For the treatment of Streptococcus pyogenes (group A b-hemolytic streptococci) pharyngitis and prevention of initial attacks (primary prevention) of rheumatic fever in children, the Infectious Diseases Society of America (IDSA), American Heart Association (AHA) and the American Academy of Pediatrics (AAP) recommend a penicillin V dosage of 250 mg 2-3 times daily for at least 10 days.

A dosage of 500 mg 2 or 3 times daily for 10 days also has been recommended for adults and adolescents. Follow-up throat cultures 2-7 days after penicillin V therapy are necessary only in patients who remain symptomatic, develop recurring symptoms, or have a history of rheumatic fever and are at unusually high risk for recurrence.

Treatment of asymptomatic pharyngeal carriers of group A streptococci generally is not indicated, and these individuals should not receive repeated courses of anti-infective therapy. However, a second course should be considered in asymptomatic individuals with a personal or family history of rheumatic fever or rheumatic heart disease.

In addition, if there is recurrence of signs and symptoms of pharyngitis shortly after the initial regimen is completed (i.e., within a few weeks) and presence of S. pyogenes is documented, retreatment with the original regimen or an alternative anti-infective agent is indicated.

If there are multiple, recurrent episodes of symptomatic pharyngitis within a period of months to years, it may be difficult to determine whether these are true episodes of S. pyogenes infection or whether the patient is a long-term streptococcal pharyngeal carrier who is experiencing repeated episodes of nonstreptococcal pharyngitis (e.g., viral pharyngitis) in whom treatment is not usually indicated. In this situation, the IDSA suggests that symptomatic individuals with multiple, recurrent episodes of documented S. pyogenes pharyngitis may receive an alternative regimen (oral clindamycin, oral amoxicillin and clavulanic acid, IM penicillin G benzathine with or without oral rifampin).

For the treatment of group A b-hemolytic streptococcal infections such as mild to moderately severe upper respiratory tract infections, otitis media, erysipelas, or scarlet fever, the usual dosage of penicillin V for adults and children 12 years of age or older is 125-250 mg every 6-8 hours for 10 days or, alternatively, 500 mg every 12 hours for 10 days.

For the treatment of mild to moderately severe respiratory tract infections caused by susceptible Streptococcus pneumoniae, including otitis media, the usual dosage of penicillin V for adults and children 12 years of age or older is 250-500 mg every 6 hours until the patient has been afebrile for at least 2 days.

For the treatment of mild skin or skin structure infections caused by susceptible nonpenicillinase-producing staphylococci, the usual dosage of penicillin V for adults and children 12 years of age or older is 250-500 mg every 6-8 hours.

Anthrax

For the treatment of mild, uncomplicated cutaneous anthrax caused by susceptible Bacillus anthracis when IV therapy is not considered necessary, the usual dosage of penicillin V is 200-500 mg orally 4 times daily in adults or 25-50 mg/kg daily given in 2 or 4 divided doses in children.

Although 5-10 days of anti-infective therapy may be adequate for the treatment of mild, uncomplicated cutaneous anthrax that occurs as the result of naturally occurring or endemic exposures to anthrax, the US Centers for Disease Control and Prevention (CDC) and other experts recommend that therapy be continued for 60 days if cutaneous anthrax occurred as the results of exposure to aerosolized Bacilllus anthracis spores since the possibility of inhalational anthrax would also exist.

For young children (i.e., younger than 2 years of age), initial therapy for cutaneous anthrax should be IV rather than oral, and combination anti-infective therapy should be considered since it currently is not known whether infants and young children are at increased risk of systemic dissemination of cutaneous anthrax.

Although anti-infective therapy may limit the size of the cutaneous anthrax lesion and it usually becomes sterile within the first 24 hours of treatment, the lesion will still progress through the black eschar stage despite effective treatment. If penicillin V is used for postexposure prophylaxis following suspected or confirmed exposure to aerosolized anthrax spores (inhalational anthrax), the CDC recommends that adults may receive 7.5 mg/kg of penicillin V orally 4 times daily and that children younger than 9 years of age may receive 50 mg/kg daily given in 4 divided doses.

Because of concerns regarding possible penicillin resistance, the initial drugs of choice for postexposure prophylaxis following a suspected or confirmed bioterrorism-related exposure to aerosolized anthrax spores are ciprofloxacin or doxycycline.

Penicillin V

If exposure is confirmed and in vitro tests indicate that the organism is susceptible to penicillin, consideration can be given to changing the postexposure prophylaxis regimen to a penicillin (e.g., amoxicillin, penicillin V). Penicillin G procaine also has been recommended for postexposure prophylaxis. Anti-infective prophylaxis should be continued until exposure to B. anthracis has been excluded.

If exposure is confirmed, postexposure vaccination with anthrax vaccine (if available) may be indicated in conjunction with prophylaxis. Because of the possible persistence of anthrax spores in lung tissue following an aerosol exposure, the CDC and other experts recommend that anti-infective prophylaxis be continued for 60 days. For additional information on treatment of anthrax and recommendations for postexposure prophylaxis following exposure to anthrax spores, see Anthrax under Uses: Gram-positive Bacterial Infections, in the Natural Penicillins General Statement and see Uses: Anthrax, in Ciprofloxacin 8:12.18.

Necrotizing Ulcerative Gingivitis

The usual dosage of penicillin V for the treatment of mild to moderately severe necrotizing ulcerative gingivitis (Vincent’s infection, trench mouth, Fusobacterium gingivitis or pharyngitis, Leptotrichia buccalis infection) in adults and children 12 years of age or older is 250-500 mg every 6-8 hours.

Prevention of Pneumococcal Infections

For prevention of pneumococcal infections in children with anatomic asplenia (e.g., congenital or resulting from surgery), functional asplenia (e.g., sickle cell disease), or hypogammaglobulinemia, some clinicians suggest that the usual dosage of penicillin V is 125 mg twice daily for children younger than 5 years of age and 250 mg twice daily for children 5 years of age or older.

Prevention of Recurrent Rheumatic Fever

For prophylaxis of recurrent rheumatic fever (secondary prophylaxis), the usual dosage of penicillin V for adults and children is 250 mg twice daily. Prevention of recurrent rheumatic fever requires long-term, continuous prophylaxis. (See Uses: Prevention of Recurrent Rheumatic Fever, in the Natural Penicillins General Statement 8:12.16.04.)

Cautions

Adverse Effects

Adverse effects reported with penicillin V potassium are similar to those reported with other natural penicillins. For information on adverse effects reported with penicillin V potassium, see Cautions in the Natural Penicillins General Statement 8:12.16.04.

Penicillin V

Precautions and Contraindications

Penicillin V potassium shares the toxic potentials of the penicillins, including the risk of hypersensitivity reactions, and the usual precautions of penicillin therapy should be observed. Prior to initiation of therapy with penicillin V potassium, careful inquiry should be made concerning previous hypersensitivity reactions to penicillins, cephalosporins, or other drugs.

There is clinical and laboratory evidence of partial cross-allergenicity among penicillins and other b-lactam antibiotics including cephalosporins and cephamycins.Penicillin V potassium is contraindicated in patients who are hypersensitive to any penicillin.

Renal and hematologic systems should be evaluated periodically during prolonged therapy with penicillin V potassium, particularly if high dosage is used. In such situations, use of penicillin V potassium for longer than 2 weeks may be associated with an increased incidence of serum sickness-like reactions. Individuals with phenylketonuria (i.e., homozygous genetic deficiency of phenylalanine hydroxylase) and other individuals who must restrict their intake of phenylalanine should be warned that Teva’s penicillin V potassium powder for oral solution contains aspartame (NutraSweet®), which is metabolized in the GI tract to phenylalanine following oral administration.

For a more complete discussion of these and other precautions associated with the use of penicillin V potassium, see Cautions: Precautions and Contraindications, in the Natural Penicillins General Statement 8:12.16.04.

Pregnancy, Fertitlity and Lactation

Safe use of penicillin V potassium during pregnancy has not been definitely established. Animal reproduction studies have not been performed with penicillin V. There are no adequate or controlled studies using penicillin V potassium in pregnant women, and the drug should be used during pregnancy only when clearly needed. Because penicillin V is distributed into milk, the drug should be used with caution in nursing women.

Spectrum Based on its spectrum of activity, penicillin V is classified as a natural penicillin.

For information on the classification of penicillins based on spectra of activity, see the Preface to the General Statements on Penicillins 8:12.16. For specific information on the spectrum of activity of penicillin V and resistance to the drug, see the sections on Spectrum and on Resistance in the Natural Penicillins General Statement 8:12.16.04.

Pharmacokinetics

For additional information on the absorption, distribution, and elimination of penicillin V, see Pharmacokinetics in the Natural Penicillins General Statement 8:12.16.04.

Absorption

Penicillin V is more resistant to acid-catalyzed inactivation than penicillin G, and the acid and potassium salt of the drug are better absorbed than penicillin G following oral administration. Approximately 60-73% of an oral dose of penicillin V or penicillin V potassium is absorbed from the GI tract in healthy, fasting adults.

Following oral administration of a single dose of penicillin V or penicillin V potassium in fasting children or adults, peak serum concentrations of penicillin V are generally attained within 30-60 minutes. Peak serum penicillin V concentrations are attained sooner and are slightly higher following administration of the potassium salt than the free acid. Following oral administration of a single 125-mg tablet of penicillin V potassium in healthy, fasting adults in one study, serum penicillin V concentrations averaged 1.2, 1.2, 0.5, and 0.1 mcg/mL at 30 minutes, 1 hour, 2 hours, and 4 hours, respectively, after the dose.

Oral administration of a single 250-mg tablet of the drug in healthy, fasting adults results in serum penicillin V concentrations averaging 2.1-2.8,2.3-2.7, 0.8-0.9, and 0.1-0.2 mcg/mL at 30 minutes, 1 hour, 2 hours, and 4 hours, respectively, after the dose. Following oral administration of a single 500-mg tablet of penicillin V potassium in healthy, fasting adults, serum penicillin V concentrations average 4.7-5, 4.9-6.3,2.3-3, and 0.04-0.1 mcg/mL at 30 minutes, 1 hour, 2 hours, and 6 hours, respectively, after the dose.

Variable results have been obtained in studies evaluating the effect of food on GI absorption of penicillin V and penicillin V potassium. In most studies, presence of food in the GI tract resulted in lower and delayed peak serum concentrations of penicillin V, although the total amount of drug absorbed was unaffected. However, results of several studies in children 2 months to 5 years of age indicate that both the peak serum concentration and the area under the serum concentration-time curve (AUC) are decreased when penicillin V potassium is administered with or immediately prior to milk or food.

Distribution

Penicillin V is readily distributed into ascitic, synovial, pleural, and pericardial fluids. The drug is widely distributed into body tissues with highest concentrations attained in the kidneys and lower amounts in the liver, skin, and intestine.

Penicillin V is also distributed into bile, tonsils, maxillary sinus secretions, and saliva in low concentrations. Minimal concentrations of penicillin V generally distribute into CSF. Penicillin V is approximately 75-89% bound to serum proteins. Penicillin V readily crosses the placenta and is distributed into milk.

Elimination

The serum half-life of penicillin V in adults with normal renal function is reportedly 0.5 hours. Approximately 35-70% of an oral dose of penicillin V or penicillin V potassium is metabolized to penicilloic acid which is microbiologically inactive.

Small amounts of 6-aminopenicillanic acid (6-APA) have also been found in urine of patients receiving penicillin V. In addition, the drug appears to be hydroxylated to a small extent to one or more microbiologically active metabolites which are also excreted in urine. Penicillin V and its metabolites are excreted in urine mainly by tubular secretion. Small amounts of the drug are also excreted in feces and bile.

Following oral administration of a single dose of penicillin V or penicillin V potassium in adults with normal renal function, 26-65% of the dose is excreted in urine as unchanged drug and metabolites within 6-8 hours; approximately 32% of the dose is excreted in feces. Renal clearance of penicillin V is delayed in neonates and young infants and in individuals with impaired renal function. It is not known if penicillin V is removed by hemodialysis or peritoneal dialysis.

Chemistry and Stability

Chemistry

Penicillin V is a natural penicillin produced by fermentation of Penicillium chrysogenum in a medium containing phenoxyacetic acid. Penicillin V is commercially available as the potassium salt. Penicillin V potassium occurs as a white, odorless, crystalline powder. Penicillin V potassium is very soluble in water and slightly soluble in alcohol, having a solubility in alcohol of approximately 6.67 mg/mL at 25°C.

Penicillin V has a pKa of 2.73. Although potency of penicillin V potassium generally is expressed in terms of the weight of penicillin V, potency of the drug may be expressed in terms of USP penicillin V units.

Each mg of penicillin V potassium has a potency of 1380-1610 USP penicillin V units. For labeling purposes, each mg of penicillin V contained in penicillin V potassium preparations is considered equivalent to 1695 USP penicillin V units; however, the manufacturers state that potency of penicillin V potassium preparations containing 125, 250, or 500 mg of penicillin V is approximately equivalent to 200,000, 400,000, or 800,000 USP penicillin V units, respectively. Each 250 mg of penicillin V as the potassium salt contains approximately 0.7 mEq of potassium.

When reconstituted as directed, solutions of penicillin V potassium have a pH of 5-7.5.

Stability

Commercially available penicillin V potassium tablets and powders for oral solution should be stored in tight containers at 15-30°C. Following reconstitution, penicillin V potassium oral solutions should be refrigerated at 2-8°C, and any unused solution should be discarded after 14 days.

For further information on chemistry and stability, mechanism of action, spectrum, resistance, pharmacokinetics, uses, cautions, drug interactions, laboratory test interferences, and dosage and administration of penicillin V, see the Natural Penicillins General Statement 8:12.16.04.

Preparations

Penicillin V Potassium Oral For solution 125 mg (of penicillin V) per Penicillin VK for Oral 5 mL Solution, (with aspartame) Teva 250 mg (of penicillin V) per Penicillin VK for Oral 5 mL Solution, (with aspartame) Teva Tablets 250 mg (of penicillin V) Penicillin V Potassium Tablets , Teva UDL 500 mg (of penicillin V) Penicillin V Potassium Tablets , Teva UDL Tablets, film- 250 mg (of penicillin V) Penicillin V Potassium Tablets coated , Sandoz 500 mg (of penicillin V) Penicillin V Potassium Tablets , Sandoz

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