Treating PIH: Retinoids favored; uncertainty surrounds hydroquinone

September 1, 2008

With hydroquinone's status in the U.S. marketplace uncertain due to safety concerns, retinoids are increasingly gaining favor in the treatment of postinflammatory hyperpigmentation.

Key Points

Sewickley, Pa. - With retinoids continuing to represent a highly effective standard of care for postinflammatory hyperpigmentation (PIH), some newer combinations are offering even better results for topical treatments.

PIH is common in dark-skinned individuals with acne or rosacea, as inflammatory lesions can leave dark spots or macules. Retinoids can offer effective treatment on a variety of levels for such patients, says Joseph Bikowski, M.D., F.A.A.D., director of the Bikowski Skin Care Center.

"Acne patients with darker complexions usually have PIH in addition to inflammatory lesions, and you want to be able to treat those with topical medications such as retinoids, which can not only help prevent the recurrence of inflammatory lesions, but also with a reduction in the incidence of PIH," Dr. Bikowski tells Dermatology Times.

One recent study indicates that combination of mequinol 2 percent and 0.01 percent tretinoin can be a more effective treatment than hydroquinone.

Study parameters

The study involved 61 black patients with PIH secondary to acne, with 61 percent of cases representing severe PIH and the remaining 31 percent with mild PIH.

In the split-face trial, one side of patients' faces was treated with hydroquinone 4 percent cream alone; the other, with a compound combining mequinol 2 percent plus tretinoin 0.01 percent (Solage, Barrier Therapeutics).

Among the 47 subjects who completed the 12-week trial, success scores were much higher in the hydroquinone sides early in the treatment, with success scores of 75 percent at four weeks and 90 percent at eight weeks, compared to 50 percent and 76 percent for mequinol 2 percent plus tretinoin 0.01 percent at the same time points.

By the twelfth week, however, the mequinol-tretinoin combination had a higher success rate of 87 percent versus 83 percent with hydroquinone 4 percent.

Both groups experienced adverse events including burning, scabbing, peeling, dryness, stinging, erythema, treatment-induced hyperpigmentation and milia, with most cases reported to be mild-to-moderate.

None of the patients withdrew from the study due to adverse events.

Further study

A fixed-dose combination of hydroquinone 4 percent and 0.15 percent retinol has emerged for the treatment of PIH, which is formulated in microsponge technology (EpiQuin Micro, SkinMedica) that releases hydroquinone gradually to extend exposure and minimize skin irritation.

In an open-label study on the system, 25 patients applied the formulation to the full face twice daily, and also used a broad-spectrum sunscreen once in the morning and 15 minutes after the application of the product. Patient evaluations at four, eight and 12 weeks showed statistically significant improvement at all points, compared with the baseline.

The lesion area and colorimetry measurements were significantly improved at each visit, and the formulation was well-tolerated, with one patient dropping out due to a non-serious allergic reaction (Cutis. 2004 Dec;74(6):362-368).

Physicians are also finding success in treating acne or rosacea-related PIH with triple combination (TC) cream containing fluocinolone acetonide 0.01 percent, hydroquinone 4 percent and tretinoin 0.05 percent.

"As soon as the TriLuma became available in a nice combination in one tube, I went to that, because it improved patient compliance and was reasonably priced for prolonged usage," he says.

The new 0.3 percent formulation of the retinoid adapalene (Differin, Galderma), approved by the Food and Drug Administration in 2007, is also a useful addition, Dr. Bikowski says.

"Topical retinoids certainly can cause some irritation, depending on the strength and type of patient being treated, and the mild adapalene formulations have shown the least amount of irritation," he says.

Disclosure: Dr. Bikowski is on the advisory boards for SkinMedica, Coria and Galderma, and also has consulting, honoraria and speakers bureau relationships with Coria and Galderma.

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