Podophyllin

Podophyllin is a resinous powder obtained by precipitating an alcoholic tincture of the rhizome of American Mayapple (Podophyllum peltatum) by means of water acidified with hydrochloric acid. It varies in color from grayish to bright yellow or greenish-brown, the first-named being the purest.

The powder is soluble in alcohol and strong solutions of alkalis, such as ammonia. Its composition is somewhat complex. There are certainly at least two resins in the powder (which is known officially as Podophylli resina), one of them being soluble and the other insoluble in ether. Each of these contains an active substance, which can be obtained in crystalline form, and is known as podophyllotoxin. It is soluble in alcohol, ether, chloroform and boiling water.

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Reactivity

Alkalis decompose it into picro-podophyllic acid and picro-podophyllin, minute traces of both of which occur in a free state in the rhizome. The acid is inert, but picro-podophyllin is the active principle.

It is a crystalline body, soluble only in concentrated alcohol. Hence the inutility of the pharmacopeial tinctura podophylli, which cannot be diluted before administration. The properties of podophyllin resin vary with the reaction of the tissue with which it is in contact; where this is acid the drug is inert, the picro-podophyllin being precipitated.

The resin does not affect the unbroken skin, but may be absorbed from a raw surface, and will then cause purging. When taken internally it is both a secretory and an excretory cholagogue, but so irritant and powerful that its use in cases of jaundice is generally undesirable. Its value, however, in certain cases of constipation of hepatic origin is undeniable. It is largely used in patent medicines, usually as an auxiliary to aloes. The best method of prescribing podophyllin is in pill form.

Toxicity

In toxic doses podophyllin causes intense enteritis, with all its characteristic symptoms, and severe depression, which may end in death. The treatment is symptomatic, there being no specific antidote.

Medical Applications

Podophyllin is also used to remove genital warts. This requires several applications of podophyllin toxin to the warts over a period of time. Podophyllin resin and podofilox lotion or gel remove genital warts by stopping cell growth. A health professional applies podophyllin resin to the warts. Petroleum jelly, such as Vaseline, to protect normal tissue near the warts from irritation. Resin is washed off within 4 hours to reduce side effects. Your health professional usually applies the resin once a week for at least 6 weeks or until warts disappear.

You can apply podofilox in lotion or gel at home. The usual schedule is twice a day for 3 days, followed by 4 days without any lotion. You repeat this schedule for 4 weeks. Podofilox lotion or gel has been found to be effective in clearing warts. It has mild side effects and is well-suited for treatment at home.

Neither podophyllin resin nor podofilox lotion or gel is used during pregnancy because these medications can be harmful to the fetus. The most common side effects near the application site are skin reactions, including:

• Burning
• Redness
• Pain
• Itching
• Swelling

Complications from podophyllin resin application are rare. Complications are more likely when podophyllin resin is:

• Applied to large areas.
• Applied to areas that are already swollen and irritated.
• Left on longer than 12 hours so that more of the medication is absorbed into the body (systemic toxicity). *Podofilox lotion or gel has milder side effects at the application area than podophyllum resin.

Podophyllin resin must be applied by a health professional so that the amount used can be carefully monitored to avoid more serious side effects.

Because podofilox lotion or gel can be applied at home, you need fewer visits to a health professional. This reduces the cost of treatment.

Neither podophyllin resin nor podofilox lotion or gel is used during pregnancy because these medications can be harmful to the fetus.

Genital warts often go away on their own. Also, treating genital warts does not cure infection with human papillomavirus (HPV), the virus that causes genital warts. The virus remains in the body in an inactive state after warts are removed. A person treated for genital warts may still be able to spread the infection. Condoms may help reduce the risk of HPV infection, but it is not known how much protection they provide.

The benefits and effectiveness of each type of treatment need to be compared with the side effects and cost. Discuss this with your health professional.

References

• This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.
• Kelly M, Hartwell J. L. (1954). "The biological effects and the chemical composition of podophyllin: a review.". Journal of the National Cancer Institute 14 (4): 967-1010.
• J. L. Hartwell, A. W. Schrecker (1951). "Components of Podophyllin. V. The Constitution of Podophyllotoxin". Journal of the American Chemical Society 73 (6): 2909 - 2916. doi:10.1021/ja01150a143.