Methoxsalen

IX. DRUG DOSAGE & ADMINISTRATION CAUTION: Methoxsalen Capsules, USP represents a new dose form of methoxsalen. This new dosage form of methoxsalen exhibits significantly greater bioavailability and earlier photosensitization onset time than previous methoxsalen dosage forms. Each patient should be evaluated by determining the minimum phototoxic dose (MPD) and phototoxic peak time after drug administration prior to onset of photochemotherapy with this dosage form. Human bioavailability studies have indicated the following drug dosage and administration directions are to be used as a guideline only. PSORIASIS THERAPY 1. DRUG DOSAGE -INITIAL THERAPY: Methoxsalen capsules should be taken 1-1/2 to 2 hours before UVA exposure with some low-fat food or milk according to the following table: Patient's Weight Dose (kg) (lbs) (mg) <30 <66 10 30-50 66-110 20 51-65 112-143 30 66-80 146-176 40 81-90 179-198 50 91-115 201-254 60 >115 >254 70 Geriatric patients should generally be started at the low end of the dose recommended according to body weight and closely monitored during PUVA therapy. Although clinical experience has not identified differences in response between elderly and younger patients, the use of methoxsalen in older individuals may be affected by the presence of pre-existing medical conditions. 2. INITIAL EXPOSURE: The initial UVA exposure energy level and corresponding time of exposure is determined by the patient's skin characteristics for sun burning and tanning as follows: *Patients with natural pigmentation of these types should be classified into a lower skin type category if the sunburning history so indicates. Skin Type History Recommended J/cm 2 I Always burn, never tan (patients with erythrodermic psoriasis are to be classed as Type I for determination of UVA dosage.) 0.5 J/cm 2 II Always burn, but sometimes tan 1.0 J/cm 2 III Sometimes burn, but always tan 1.5 J/cm 2 IV Never burn, always tan 2.0 J/cm 2 Skin Type Physician Examination J/cm 2 V* Moderately pigmented 2.5 J/cm 2 VI* Blacks 3.0 J/cm 2 If the MPD is done, start at 1/2 MPD. Additional drug dosage directions are as follows: Weight Change: In the event that the weight of a patient changes during treatment such that he/she falls into an adjacent weight range/dose category, no change in the dose of methoxsalen is usually required. If, in the physician's opinion, however, a weight change is sufficiently great to modify the drug dose, then an adjustment in the time of exposure to UVA should be made. Dose/Week: The number of doses per week of methoxsalen capsules will be determined by the patient's schedule of UVA exposures. In no case should treatments be given more often than once every other day because the full extent of phototoxic reactions may not be evident until 48 hours after each exposure. Dosage Increase: Dosage may be increased by 10 mg. after the 15th treatment under the conditions outlined in section XI.B.4.b. X. UVA RADIATION SOURCE SPECIFICATIONS AND INFORMATION A. IRRADIANCE UNIFORMITY The following specifications should be met with the window of the detector held in a vertical plane: Vertical Variation: For readings taken at any point along the vertical center axis of the chamber (to within 15 cm from the top and bottom), the lowest reading should not be less than 70 % of the highest reading. Horizontal Variation: Throughout any specific horizontal plane, the lowest reading must be at least 80 % of the highest reading, excluding the peripheral 3 cm of the patient treatment space. B. PATIENT SAFETY FEATURES: The following safety features should be present: (1) Protection from electrical hazard: All units should be grounded and conform to applicable electrical codes. The patient or operator should not be able to touch any live electrical parts. There should be ground fault protection. (2) Protective shielding of lamps: The patient should not be able to come in contact with the bare lamps. In the event of lamp breakage, the patient should not be