On rifampin treatment of psoriasis

Correspondence On rifampin treatment of psoriasis To the Editor: We read the article "A Therapeutic Trial of the Use of Penicillin V or Erythromycin With or Without Rifampin in the Treatment of Psoriasis" by Vincent et al. (J AM ACAD DERMATOL 1992;26:458-61) with great interest. The authors conclude that there was no apparent benefitfor patients with Streptococcus-associated psoriasis. We recently published the results of our study on 10 patients with severepsoriasis treated with rifampin.' Not all patients had clinical or microbiologic evidence of streptococcal carriage. Rifampin, 300 mg, twice daily, was administered for 30 days to sevenpatients and for 45 days to three patients.There was moderate improvement to complete remission in six patients. The patients also reported significant relief from pruritus. Rifampin has an antipruritic effect in patients with biliary cirrhosis.v 3 However, a similar mechanism of action is unlikely in psoriasis. In experimental studies rifampin suppresses humoral as well as cellularimmune responses but so far no clinical equivalent of this phenomenon has been observed." Our resultsseem to justify further studies on the antipruritic and immunosuppressive effects of more prolonged rifampin treatment in patients with psoriasis. Nikolai Tsankov, MD, PhD Maya Krasteva, MD Institute of Dermatology 1, G. Sofiyski Str. 1431 Sofia, Bulgaria

REFERENCES 1. Tsankov N,Krasteva M. Rifampicin therapy insevere forms of psoriasis. J Dermatol Treat J 992;3:69-71. 2. Bachs L,Pares A,Elena M, et al.Comparison ofrifampicin

withphenobarbitone for thetreatment ofpruritus in biliary cirrhosis. Lancet 1989;1:574-6. 3. Bernhard JD. Pruritus: advances in treatment. Adv Dermatol1991;6:57-71. 4. Tsankov N, Karnarashev 1. Rifampicin indermatology. Int J Dermato1 1993;32:401-6.

Reply To the Editor: We read the letter of Tsankov and Kresteva with interest. Their group of 10 patients is small and without controls.' Only 6 of the 10patients werereported to be improved or have complete remission in 30 to 45 days with rifampicin only. Two different dose regimens were used. It was not stated whether the patients were treated as inpatientsor as outpatients. The AST, regarded as significant at more than 200 units, was the only serologic test used.Our study, whichwas controlled, followed the preliminary report of Rosenberg et al,,2 in which rif-

ampicin was added in the last 5 days of a 14-day course of penicillin or erythromycin. As Tsankov and Kresteva state, we were unable to show any benefit. Psoriasis is remarkably variable in its natural history. Therefore it is difficult to determine efficacyof treatment in small numbers of patients in uncontrolled trials. We recall an initial enthusiasm for the use of intramuscular vitamin B12 for the management of psoriasis that was subsequently refuted by a controlled study.' The reported association between infection and psoriasis3 is strongenoughto warrant continued study. To date there has been no significant response to antibiotic treatment reported in an adequately controlled trial. Although rifampicinmay yet be proved to be beneficialfor the condition, we are concerned that if more patients receivethe drug in the dosage and duration given by Tsankov and Krasteva in contrast to our study, they may be subject to significant adverse effects. In our view, only larger wellcontrolled trials performed collaboratively between several different geographiccenters willshow whether antibiotic treatment of psoriasis is effective. J. Barrie Ross, ME, FRCPCG Franklynne Vincent, MD, FRCPCb Division ofDermatology, Department of Medicine, Dalhousie University, Halifax, Nova Scotia" Toronto, Ontario' REFERENCES

I. Tsankov N, Krasteva M. Rifampicin therapy insevere forms of psoriasis. J Dermatol Treat 1992;3:69-71. 2. Rosenberg EW, Noah PW, Zanolli MD, et al. Use of rifampin with penicillin and erythromycin in the treatment

of psoriasis. JAM ACAD DERMATOL 1986;14:761-4. 3. Baker H, ComaishJS. Is vitamin Bl2 of value in psoriasis? Br Med J 1962;2: \729-30.

Is the screening patch test tray still worth using? To the Editor: A recent American Academy of Dermatology survey of the members by James et al. indicated that approximatelyonethird do not patch test patients for evaluation of possible contact allergy (J AM ACAD DERMATOL 1992;26:991-4). Among the reasons cited by the non-patch-testing dermatologists is that there are not enough allergens available to make testing worthwhile. The allergen patch test series currently available in the United States (Hermal, Inc., Delmar, N.Y.) consists of 20allergensor allergenmixes and isdesignedto detect the most frequent contact allergens (other than poison ivy/ oak) likely to be encountered by patients in this country. A figureof 80% is quoted as the percentage of contact allergies that this screening series can detect. I.2 A recent

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