Pyrithione zinc is a topical antiseborrheic agent. It is a cytostatic agent that reduces the turnover rate of the epidermal cells and is used to help control dandruff and seborrheic dermatitis of the body and scalp. It also exhibits antifungal and antibacterial properties. Pyrithione zinc is effective in controlling dry scalp and associated symptoms and is also used in the treatment of tinea versicolor and psoriasis. Pyrithione zinc is also employed as a preservative in alcohol-based antiseptic products to provide antimicrobial persistence for sustained periods of skin antisepsis. It was first compounded in the 1930s, and its primary function was as an antifungal agent; pyrithione zinc was approved by the FDA in 1961.
General Administration Information
For storage information, see the specific product information within the How Supplied section.
Route-Specific Administration
Topical Administration
-Do not apply to thin skin areas or mucous membranes.
Cream/Ointment/Lotion Formulations
-Cream: Apply directly to the affected area and rub in gently.
Other Topical Formulations
-Cleansing bar: Lather cleansing bar using warm water, massage into affected areas. Rinse well.
-Shampoo: Apply to wet hair and massage into hair and scalp, working up a lather. Leave on the scalp for several minutes, then thoroughly rinse. The process may be repeated.
-Spray: Apply to affected area thoroughly.
Use of pyrithione zinc may result in skin irritation.
The use of pyrithione zinc is contraindicated in patients with known pyrithione hypersensitivity.
There have been no documented problems in humans following the use of topically administered pyrithione zinc products during pregnancy.
The use of pyrithione zinc has not been reported to cause problems when used during breast-feeding.
Pyrithione zinc is not recommended for use in the treatment of seborrheic dermatitis in neonates and infants (i.e., cradle cap).
For the treatment of seborrheic dermatitis or dandruff:
Topical dosage (cleansing bar):
Adults: Wash affected area in place of regular soap; use at least twice weekly for best results.
Topical dosage (shampoo):
Adults: Wash hair and scalp in place of regular shampoo; use at least twice weekly for best results.
Topical dosage (cream and spray):
Adults: Apply to affected area 1 to 4 times daily.
For the treatment of tinea versicolor*:
Topical dosage (shampoo):
Adults: Once daily, apply shampoo to skin as a lotion, leave on for 5 minutes, and then rinse off. Treatment should continue for 2 weeks.
Maximum Dosage Limits:
No maximum dosage information is available.
Patients with Hepatic Impairment Dosing
Specific guidelines for dosage adjustments in hepatic impairment are not available; it appears that no dosage adjustments are needed.
Patients with Renal Impairment Dosing
Specific guidelines for dosage adjustments in renal impairment are not available; it appears that no dosage adjustments are needed.
*non-FDA-approved indication
There are no drug interactions associated with Pyrithione Zinc products.
Pyrithione zinc is thought to treat skin conditions by its actions as a cytostatic agent and through its antifungal and antibacterial activity. The cytostatic actions suppress cellular growth and multiplication, resulting in a reduction in the turnover of epidermal cells. Pyrithione zinc exhibits in vivo and in vitro activity against multiple fungi, bacteria, and yeast, but it appears that the antifungal activity is most useful in treating common skin conditions. Pyrithione is a general inhibitor of membrane transport processes in fungi; the degree of transport inhibition increases with increasing exposure time to pyrithione. Specifically, pyrithione zinc has good antifungal activity against Malassezia species of fungus, an organism normally present on the skin but appears to overgrow in conditions such as dandruff and seborrheic dermatitis.
Pharmacokinetics:
Pyrithione zinc is administered topically to the skin as a bar soap, lotion, cream, or shampoo. Most pyrithione zinc-based shampoos available today are manufactured by shaping pyrithione zinc as a thin plate, 2.5 microns across. This allows the pyrithione zinc to precipitate on the scalp during shampooing and remain on the scalp after rinsing the shampoo from the hair. Active product then remains on the scalp, preventing fungal recolonization and delaying the return of dandruff and resultant seborrheic dermatitis. Older manufacturing processes of pyrithione zinc-based shampoos allowed for the pyrithione zinc to remain as a particulate, produced in a cuboidal shape and suspended in a shampoo base; this formulation did not allow for as effective delivery of the pyrithione onto the scalp.
-Route-Specific Pharmacokinetics
Topical Route
Following topical application, pyrithione zinc is deposited in the epidermis, with the largest proportion being deposited on the outer layers of the stratum corneum. Pyrithione zinc is soluble in sebum, and when applied to the skin pyrithione is localized in the hair follicles. No transepidermal penetration occurs. Deposited particles of pyrithione zinc appear to adhere firmly to the hair and stratum corneum and to withstand copious rinsing. These adherent particles probably act as a reservoir and are responsible for prolonged antimicrobial effects. Diminution of the antibacterial effect with time is probably due to normal turnover of the stratum corneum.