A 76-year-old woman has since August 1992 had recurring unilaterally reddish exanthema on the skin

Fråga: A 76-year-old woman has since August 1992 had recurring unilaterally reddish exanthema on the skin of the hip. She has been treated with several antihypertensive drugs (Midamor, Plendil, Seloken and Lasix). The last recurrence appeared two weeks after reinstitution of isradipine. Have fixed drug eruptions previously been reported for calcium antagonists (felodipine, isradipine)? Are cross-reactions known? The patient is now on isradipine and lisinopril treatment.

Sammanfattning: Cutaneous side-effects are rather common among the dehydropyridines. Isradipine has been on the market for only a short period of time and, therefore, only a few cases can be expected none of which have been reported to the Swedish Side Effect Register. Nifedipine has been found to cause fixed drug eruptions in a single case. It is concluded that isradipine may be the cause of fixed drug eruption in the present case.

Svar: The calcium antagonisms licensed for cardiovascular use in Sweden belong either to the group of dehydropyridines such as nifedipine, isradipine, felodipine etc, or they are chemically different from this class of compound: diltiazem and verapamil (1). In general, side-effects not related to the mechanism of clinical action of a compound sometimes occur within a chemical class but are not likely to be elicited by compounds with a different chemical structure even if they have the same mode of action with respect to the clinical effects. Fixed drug eruptions can be elicited by compounds having entirely different clinical indications, mode of actions, clinical side-effects and chemical structures (2). The published papers on fixed drug eruptions are limited to case studies, and it is notoriously difficult to find papers other than case reports. The severity of fixed drug eruption can vary considerably (2,3,4).

Although diltiazem is known to cause dermatological side-effects, these will not be discussed here because the compound is chemically different from isradipine and acts on a different class of calcium channels. Hence, there is no reason to assume that cross reactivity between diltiazem and dihydropyridines should exist. Cutaneous side-effects of dihydropyridines is not an uncommon symptom. For felodipine 68 out of a total of 279 reported side-effects to the Swedish Side Effect Register (5) were dermatological. However, for isradipine, which is a relatively new compound, there are no reports in the Swedish Side Effect Register. Unfortunately, fixed drug eruption is not a specific class in registration of these side effecs (5). In reference literature, erythematous rash with painful oedema, photosensitivity and generalised bullous eruption has been attributed to nifedipine (6). There is one case report of a fixed drug eruption due to nifedipine (7). The patient was an 80-year-old man who had been treated for several months with nifedipine before he was admitted to hospital having a large bullous fixed drug eruption. A rechallenge, made by the patient, resulted in reappearance of the eruption. It is suggested that the present case be reported to the SADRAC. 1 FASS 1994 2 Raviglione MC, Pablos-Mendez A, Battan R: Clinical features and management of severe dermatological reactions to drugs. Drug Safety 1990; 5: 39-64 3 Sehgal VN, Gangwani OP: Hydralazine-induced fixed drug eruption. Int J Dermatol 1986; 25: 394 4 Baird BJ, de Villez RL: Widespread Bullous fixed drug eruption mimicking toxic epidermal necrolysis. Int J Dermatol 1988; 27: 170-174 5 Swedis 6 Alcalay J, Sandbank DM: Cutaneous reactions to nifedipine. Dermatologica 1987; 175: 191-193