Sau khi uống, có những khác biệt đáng kể liên và intraindividual trong sự hấp thu của 8-MOP. Vì vậy, nó là rất quan trọng là liều psoralen, loại và số lượng thức ăn, và thời gian của đèn chiếu sau khi uống psoralen được giữ không đổi. Psoralen là thích hợp hơn để được thực hiện trên một dạ dày trống rỗng | 134 Kerr et al. 70 mg. Following oral administration there are significant inter- and intraindividual variations in the absorption of 8-MOP. Therefore it is very important that the psoralen dose type and amount of food intake and timing of phototherapy after ingestion of psoralen are kept constant. Psoralen is preferable to be taken on an empty stomach as food intake slows absorption and reduces the peak blood levels. However due to gastrointestinal side effects especially with 8-MOP non-fat small meals may be taken to alleviate some of these symptoms. In some patients the capsules may have to be ingested 10 minutes apart to minimize the gastrointestinal side effects. Antiemetics may have to be given to some patients. In patients who are unable to tolerate systemic PUVA psoralen can be administered in a bath or cream lotion avoiding the gastrointestinal tract. In our institution topical PUVA is administered using 8-MOP solution in Lubriderm lotion applied 20 minutes prior to exposure to UVA. The UVA dose protocol is shown in Table 3. Bath PUVA is only performed in very few centers in the United States because of the need for a bathtub. A bath containing L of 8-MOP or mg L of TMP needs to be freshly prepared the patient will then soak in it for 15 to 30 minutes. At some phototherapy facilities . University of California San Francisco UCSF effective bath PUVA is being conducted simply by dissolving 50 mg of Oxsoralen Ultra in a hot cup of water first and then adding it to 100 L of bath water. Exposure to the UVA needs to be performed within 30 minutes after the patient steps out of the bathtub. In Europe oral 5-MOP is commonly used. It is less phototoxic than 8-MOP therefore requiring a higher cumulative UVA dose. The dose range used is kg. It has less of a gastrointestinal side effect hence is better tolerated. It is not available in the United States. Avoidance of prolonged sun exposure and wearing UVA-absorbing sunscreens on the .
