INTRODUCTION
The clinical usefulness of patch testing in adverse cutaneous reaction has been reported, especially for systemic contact dermatitis. However, the clinical characteristic of cutaneous reactions are polymorphous and the pathophysiological mechanisms cannot be defined.
Captopril is an angiotensin-converting enzyme (ACE) inhibitor. Its delated cutaneous reactions have been reported, but there have been few reports of cutaneous reactions to captopril with positive patch test.
CASE REPORT
We presented the case of a patient who developed a cutaneous reaction induced by captopril. A 74-year-old man, began oral treatment for hypertension with the angiotensin-converting enzyme (ACE) inhibitor captopril 25 mgr, one time daily. He has been diagnosticated of glomerulonephritis and chronic renal insufficiency 3 years ago. His medications included furosemide and prednisone. Two months after, he developed a pruritic maculopapular rash involving his trunk, back and lower extremities, and he was treated initially with an hydrocortisone cream and diphenhydramine. These symptons improved completely within 20 days of stopping the hypertension treatment.
MATERIAL AND METHODS
Pach testing was performed with captopril, furosemide, prednisone, other ACE inhibitors (enalapril, lisinopril, ramipril) and European standard series (True-Test-Alk-Abello, Madrid Spain). Commercial captopril (Capoten), as well as commercial enalapril (Renitecn), lisinopril (Donekan) and ramipril (Caraseln) were tested at 10 % pet.
A double-blind oral challenge was performed with enalapril and lisinopril in order to find an alternative treatment.
RESULTS
Positive reaction were obtained to commercial captopril at 4 days. The same test were negative in 5 control patients without adverse cutaneous reaction to captopril. The only positive reaction was to captopril, wich was confirmed by a repeated positive reaction.
We performed a double-blind oral challenge test with Renitecn and Donekan. The patient tolerated enalapril and lisinopril without problems.
DISCUSSION
Up to 15 % of patients treated with captopril develop a rash during the first few weeks of treatment: maculopapular, urticarial, pityriasis rosea-like, psoriasis-form, and lupus erythematosus-like have all been reported with captopril (1). There have been also few reports of systemic reactions to ACE inhibitors (2).
The clinical usefulness of patch testing in adverse cutaneous drug reactions has been recognized. The only study performed on a sample of 15 patients with captopril reactions gave positive results in 1/3 of the cases (3). When patch tests are performed with several ACE inhibitors, results seem to indicate an absence of cross-sensitivity permiting the replacement of the causative drug by another product ot the same family. In several patients, oral provocation test were needed because patch tests gave no conclusive information.
Captopril is the only such drug containing a sulfydryl group, wich is considered to be cause of positive patch test reactions (4). The negative patch test, as well as oral tolerance, of other ACE inhibitors lead us to believe that there is no cross-reactivity among these compounds (5).
The allergological studies confirmed sensitisation to captopril and tolerance to lisinopril and enalapril. This case confirms that in the contact dermatitis due to ACE inhibitors drugs sensitisation it is not always necessary to prohibit the use of all the drugs in the pharmacological group of the one causing the reaction. An allergological study is advisable in order to stablish which drugs should be avoided.
