PODOFILOX

PODOFILOX- podofilox solution
Paddock Laboratories, Inc.

DESCRIPTION

Podofilox Topical Solution is an antimitotic drug which can be chemically synthesized or purified from the plant families Coniferae and Berberidaceae (e.g. species of Juniperus and Podophyllum). Podofilox Topical Solution 0.5% is formulated for topical administration. Each milliliter of solution contains 5 mg of podofilox, in a vehicle containing lactic acid and sodium lactate in alcohol 95%, USP.

Podofilox has a molecular weight of 414.4 daltons, and is soluble in alcohol and sparingly soluble in water. Its chemical name is 5,8,8a,9-Tetrahydro-9-hydroxy-5-(3,4,5-trimethoxylphenyl)furo[3',4':6,7] naphtho[2,3,d]-1, 3-dioxol-6(5aH)-one. Podofilox has the following structural formula:

Chemical StructureChemical Structure

CLINICAL PHARMACOLOGY

Mechanism of Action

Treatment of genital warts with podofilox results in necrosis of visible wart tissue. The exact mechanism of action is unknown.

Pharmacokinetics

In systemic absorption studies in 52 patients, topical application of 0.05 mL of 0.5% podofilox solution to external genitalia did not result in detectable serum levels. Applications of 0.1 to 1.5 mL resulted in peak serum levels of 1 to 17 ng/mL one to two hours after application. The elimination half-life ranged from 1.0 to 4.5 hours. The drug was not found to accumulate after multiple treatments.

CLINICAL STUDIES

In clinical studies with podofilox solution, the test product and its vehicle were applied in a double-blind fashion to comparable patient groups. Patients were treated for two to four weeks, and reevaluated at a two-week follow-up examination. Although the number of patients and warts evaluated at each time period varied, the results among investigators were relatively consistent.

The following table represents the responses noted in terms of frequency of response by lesions treated and the overall response by patients. Data are presented for the 2-week follow-up only for those patients evaluated at that time point.

Response in Treated Patients
Initially Cleared * Recurred after Clearing Cleared at 2-Week Follow-up *
*
Cleared and clearing mean no visible wart tissue remained at the treated sites
% Warts(n=524) 79%(412/524) 35%(146/412) 60%(269/449)
% Patients(n=70) 50%(35/70) 60%(21/35) 25%(14/57)

PODOFILOX Indications and Usage

Podofilox Topical Solution 0.5% is indicated for the topical treatment of external genital warts (Condyloma acuminatum). This product is not indicated in the treatment of perianal or mucous membrane warts (see PRECAUTIONS).

Diagnosis

Although genital warts have a characteristic appearance, histopathologic confirmation should be obtained if there is any doubt of the diagnosis. Differentiating warts from squamous cell carcinoma (so-called “Bowenoid papulosis”) is of particular concern. Squamous cell carcinoma may also be associated with human papillomavirus but should not be treated with Podofilox Topical Solution 0.5%.

CONTRAINDICATIONS

Podofilox Topical Solution 0.5% is contraindicated for patients who develop hypersensitivity or intolerance to any component of the formulation.

WARNINGS

Correct diagnosis of the lesions to be treated is essential. See the Diagnosis subsection of the INDICATIONS AND USAGE statement.

Podofilox Topical Solution 0.5% is intended for cutaneous use only. Avoid contact with the eye. If eye contact occurs, patient should immediately flush the eye with copious quantities of water and seek medical advice.

PRECAUTIONS

General

Data are not available on the safe and effective use of this product for treatment of warts occurring in the perianal area or on mucous membranes of the genital area (including the urethra, rectum and vagina). The recommended method of application, frequency of application, and duration of usage should not be exceeded (see DOSAGE AND ADMINISTRATION).

Information for Patients

The patient should be provided with a Patient Information leaflet when a Podofilox Topical Solution prescription is filled.

Carcinogenesis, Mutagenesis and Impairment of Fertility

Reports of lifetime carcinogenicity studies in mice are not available. Published animal studies, in general, have not shown the drug substance, podofilox, to be carcinogenic.1,2,3,4,5 There are published reports that, in mouse studies, crude podophyllin resin (containing podofilox) applied topically to the cervix produced changes resembling carcinoma in situ.6 These changes were reversible at five weeks after cessation of treatment. In one reported experiment, epidermal carcinoma of the vagina and cervix was found in 1 out of 18 mice after 120 applications of podophyllin7 (the drug was applied twice weekly over a 15-month period).

Podofilox was not mutagenic in the Ames plate reverse mutation assay at concentrations up to 5 mg/plate, with and without metabolic activation. No cell transformation related to potential oncogenicity was observed in BALB/3T3 cells after exposure to podofilox at concentrations up to 0.008 µg/mL without metabolic activation and 12 µg/mL podofilox with metabolic activation. Results from the mouse micronucleus in vivo assay using podofilox 0.5% solution in concentrations up to 25 mg/kg, indicate that podofilox should be considered a potential clastogen (a chemical that induces disruption and breakage of chromosomes).

Daily topical application of Podofilox Topical Solution 0.5% at doses up to the equivalent of 0.2 mg/kg (5 times the recommended maximum human dose) to rats throughout gametogenesis, mating, gestation, parturition and lactation for two generations demonstrated no impairment of fertility.

Pregnancy

Teratogenic Effects:

Pregnancy Category C:

Podofilox was not teratogenic in the rabbit following topical application of up to 0.21 mg/kg (5 times the maximum human dose) once daily for 13 days. The scientific literature contains references that podofilox is embryotoxic in rats when administered systemically in a dose approximately 250 times the recommended maximum human dose.8,9 Teratogenicity and embryotoxicity have not been studied with intravaginal application. Many antimitotic drug products are known to be embryotoxic. There are no adequate and well-controlled studies in pregnant women. Podofilox should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Nursing Mothers

It is not known whether this drug is excreted in human milk. Because of the potential for serious adverse reactions in nursing infants from podofilox, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.

Pediatric Use

Safety and effectiveness in pediatric patients have not been established.

Adverse Reactions to PODOFILOX

In clinical trials, the following local adverse reactions were reported at some point during treatment.

Adverse Experience Males Females
Burning 64% 78%
Pain 50% 72%
Inflammation 71% 63%
Erosion 67% 67%
Itching 50% 65%

Reports of burning and pain were more frequent and of greater severity in women than in men.

Adverse effects reported in less than 5% of the patients included pain with intercourse, insomnia, tingling, bleeding, tenderness, chafing, malodor, dizziness, scarring, vesicle formation, crusting edema, dryness/peeling, foreskin irretraction, hematuria, vomiting and ulceration.

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