8-Methoxypsoralen levels in blood of vitiligo patients and in skin, ophthalmic fluids, and ocular tissues of the guinea pig.

8-Methoxypsoralen (8-MOP) levels in the blood of vitiligo patients were determined through the use of a reverse-phase high-performance liquid chromatographic method. The overall recovery of the internal standards was 85-94%, with the lower detection limit of 8-MOP at 2 ng. Peak blood levels as low as 130 ng/ml and as high as 3892 ng/ml were obtained in patients at 1-3 h following the oral administration of 0.6 mg/kg body weight of Oxsoralen capsules (Elder Pharmaceuticals Co.). These results are consistent with the clinical observation that maximum response in phototherapy is obtained at about 2 h after oral administration of the drug. Two hours after oral administration of 0.6 mg/kg of Oxsoralen, 8-MOP levels in the epidermis, dermis, and whole skin of the guinea pig (in ng/g) were: epidermis, 330 +/- 20; dermis, 89 +/- 16; whole skin, 379 +/- 19. Also detected were 8-MOP levels of 441 +/- 22 ng/ml in aqueous humor, 166 +/- 18 ng/ml in vitreous gel, 355 +/- 15 ng/g in lens, and 410 +/- 26 ng/g in retina. These results point to the fact that the eyes of the patient must be protected from exposure to sunlight after psoralen UV treatment, and that 8-MOP is absorbed in blood unevenly and varies from patient to patient. The fact that only 50-60% of the patients responded to psoralen photochemotherapy for vitiligo may be related to the variation of absorption of the drug in individual patients.

Autoantibodies and their clinical significance in a black vitiligo population.

The frequency of autoantibodies was determined in 70 black vitiligo patients and controls. Both groups were screened for antithyroid, antinuclear, antigastric parietal cell, anti-smooth muscle cell, and antimitochondrial autoantibodies. The significance of autoantibodies was determined in vitiligo patients by correlating their presence or absence with various clinical features of the patients. The overall frequencies of autoimmune and endocrine diseases were also assessed in vitiligo patients, controls, and their respective families. Vitiligo patients had an increased frequency of antithyroid antibodies and an increased frequency of autoimmune and/or endocrine diseases. These diseases included, especially, hyperthyroidism, hypothyroidism, and alopecia areata. Autoantibody-positive vitiligo patients had an increased frequency of first- and second-degree relatives having autoimmune and/or endocrine diseases. These findings tend to support an autoimmune cause of vitiligo in black patients.

Determination of trimethylpsoralen in blood, ophthalmic fluids, and skin.

Trimethylpsoralen (TMP) levels in the blood of vitiligo patients were determined through the use of a high-performance liquid chromatographic method. TMP was extracted from blood buffered at pH 9.0 with 95:5 (V/V) hexane-isopropanol mixture; evaporated to dryness, and reconstituted in 50 microliters of ethanol. A 10-microliters aliquot was injected into a Micropack MCH-10 column (Varian HPLC model #5000). The mobile phase consisted of a mixture of water and acetonitrile with a linear gradient. The retention time of TMP was 16.5 min. The calibration curve of the external standards was linear. Overall recovery of the internal stands was 75-92%, with the lower detection limit of TMP at 2 ng/ml. Peak blood levels as low as 140 ng/ml and as high as 800 ng/ml were obtained in vitiligo patients 1-2 hr following the oral administration of 30 mg of trioxsalen tablets (Paul B. Elder Co.). Blood TMP levels peaked consistently at 2 hr when patients were fasted for 8 hr prior to drug ingestion. These results are consistent with the clinical observation that maximum response due to phototherapy is obtained 1-2 hr after oral administration of the drug. Two hours after oral drug administration, TMP levels in the epidermis, dermis, and whole skin of the guinea pig (in ng per g tissue) were: epidermis, 226 +/- 15; dermis, 25 +/- 6; and whole skin 176 +/- 12. Also detected were TMP levels 244 +/- 17 ng/ml in aqueous humor and 63 +/- 6 mg/ml in vitreous humor. These results point to the fact that the eyes of patients must be protected from overexposure to sunlight after psoralen-ultraviolet treatment.

Determination of optimal topical photochemotherapy for vitiligo.

The efficacy of topical 8-methoxypsoralen (8-MOP) in varying concentrations and vehicles was assessed in 73 vitiligo patients. The response rates in different anatomic sites were also assessed. Seven patients (9%) had 100% repigmentation; 26 (36%) had 50% or greater repigmentation, 29 (40%) had some degree of pigment return, but less than 50%; 11 (15%) had no repigmentation. Results suggest that neither concentration of drug nor vehicle is a crucial factor for inducing repigmentation of vitiliginous patches on the face, trunk, and extremities. Low-dose 8-MOP (0.1%) was as effective as high dose 8-MOP (0.5%, 1%), while causing fewer side effects. However, when treating recalcitrant areas (distal extremities), 1% 8-MOP may be the most efficacious preparation for topical photochemotherapy. A phototoxic response preceded repigmentation in all cases. The following responses were obtained for the various anatomic sites treated: 56% of facial lesions; 35% of trunk areas; 36% of the extremities, and 13% of the recalcitrant areas had greater than 50% repigmentation.