Study of pharmacokinetics and cutaneous photosensitization of hemoporfin in healthy volunteers

Background Hemoporfin is a porphyrin-based photosensitizer and has been used for photodynamic therapy of port wine stain birthmarks in China. This study assessed the pharmacokinetics and cutaneous photosensitization of Hemoporfin in healthy volunteers. Methods Sixteen healthy subjects received a single intravenous infusion injection of Hemoporfin (5 mg/kg). The concentrations of Hemoporfin (MHD) and its metabolite Haematoporphyrin (HP) in plasma, urine and faeces were determined. The pharmacokinetic parameters were calculated. In addition, the cutaneous photosensitization was evaluated under the irradiation of solar simulator, 532 nm laser, and sunlight. Results The Cmax of MHD and HP were 46.7 ± 8.41 and 1.04 ± 0.265 μg/ml, respectively. The t1/2 of MHD and HP were 5.09 ± 0.945 and 5.71 ± 2.65 h, respectively. The AUC0-24h of MHD and HP were 29.8 ± 6.19 and 0.757 ± 0.285 h·μg/ml, respectively. The AUC0–∞ of MHD and HP were 29.8 ± 6.2 and 0.792 ± 0.308 h·μg/ml, respectively. The cumulative fecal excretion rate of MHD and HP were 45.3% and 1.05% at 96 h, respectively. Whereas, the cumulative urinary excretion rate of MHD was only 0.132% at 96 h. The concentration of HP in urine was less than 10% of MHD. After 52 h of administration, the cutaneous photosensitization associated with the exposure to various light sources was minimal. Conclusion MHD and HP were excreted mainly through the faeces after intravenous infusion. Hemoporfin associated cutaneous photosensitization was insignificant.