Evaluation of minimal erythema dose in patients who use dihydropyridinic calcium channel blockers

Evaluation of minimal erythema dose in patients who use dihydropyridinic calcium channel blockers. Aim-hypothesis: Flushing as a result of vasodilatation is an expected side effect of calcium channel blockers used in the treatment of hypertension. Thus, patients using these drugs may have a lower minimal erythema dose (MED) of ultraviolet light This study aims to investigate the possible phosensitivity effect of dihydropyridinic calcium channel blockers by MED measurements. Methods: MED measurements of 39 hypertensive patients on dihydropyridinic calcium channel blockers were completed after one week of treatment and these values were compared with MED measurements obtained prior to therapy. UV 7002 phototherapy cabin was used. UVA in 8 increments of 0.2j/cm2, beginng with 0.2j/ cm2 and up to 1.6 j/cm2 was irradiated to the back of patients who wore a cover designed to leave only the test areas open. All patients used eye protection for UVA and UVB. Results: There was no significant difference between pretreatment MED (MED1) values and MED measurements obtained after one week of dihydropyridinic calcium channel blocker use (MED2) (p:0.206). A different value for MED2 compared with MED1 was observed in 3 of the 20 female patients and 4 of the 19 male patients. Gender, age and skin phototype were found to be unrelated to any change from MED1 to MED2 (p:0.695, 0.347, 1.00 respectively). Drug type or dosage were not of importance either (p:0.105 and 0.222). Conclusion: Based on the hypothesis that patients who use dihydropyridinic calcium channel blockers may have a lower erythema threshhold due to their vasodilatation effect, change in MED values in relation to dihydropyridinic calcium channel blocker use was investigated in this study. No statistically significant change in MED measurements prior and after therapy were observed in 39 patients. Thus we conclude that this group of drugs is not a cause of phototoxic reaction. However as photosensitivity may not only be of a toxic nature but could also be the result of an allergic raction our findings are limited to solely exclude the phototoxic effects of these compounds. Considering the common use of these drugs studies with larger number of patients and longer follow-up are warranted to fully define the nature their photosensitivity effects. Keywords: hypertension, dihydropyridine, calcium channel blocker, MED, photosensitivity