A. Said et al., SPECTROFLUOROMETRIC DETERMINATION OF 5-METHOXYPSORALEN PHARMACOKINETIC IN PATIENTS SERUM, Experimental dermatology, 6(2), 1997, pp. 57-63
In medicine, psoriasis and vitiligo are most often treated with PUVA t
herapy (psoralen plus ultraviolet A). The determination of psoralen in
patients' blood is necessary, as it is admitted that the therapeutic
efficiency depends on drug concentration in patients' serum. The amoun
t of UVA to administer is inversely proportional to serum peak concent
ration. High-performance liquid chromatography (HPLC) and gas chromato
graphy are the most employed methods for determining psoralens in pati
ents' serum. The 2 techniques are precise and very sensitive, but time
consuming. The aim of this paper is to propose a suitable method whic
h is rapid and simple. It is a spectrofluorimetric technique for 5-met
hoxypsoralen (5-MOP) determination in the serum of patients treated wi
th PUVA therapy. 5-MOP extraction was carried out with an heptane/ dic
hloromethane mixture (4/1; v/v), according to the Stolk method (1980).
A calibration curve (CC) was plotted from 5-MOP concentrations (range
50, 100, 200, 300, 400, 500 ng/ml). The CC was linear with a good coe
fficient of correlation: r=0.9971, and a suitable coefficient of varia
tion (CV) of 7.0%. The recovery of the method ranged from 85.3 +/- 4.2
to 108 +/- 4.1%. The assay precision gave a CV ranging from 0.10 to 6
.90%, with an error inferior to +/-10%. The method did not reveal any
interference from serum components on the 5-MOP emission wavelength. T
he limit of detection of 5-MOP was 15 ng/ml. The proposed procedure wa
s proved to be appropriate for a rapid determination of 5-MOP in patie
nts' serum. This technique could also be employed for other psoralens
used in PUVA therapy (e.g., 8-methoxypsoralen).