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PubMed2003

LC determination of impurities in methoxsalen drug substance: isolation and identification of isopimpinellin as a major impurity by atmospheric pressure chemical ionization LC/MS and NMR.

A gradient elution LC method was developed to separate methoxsalen from three of its known impurities: isopimpinellin, bergapten, and ammidin. The method employs a methanol-6%THF (aq) mobile phase, phenyl column, and detection at 254 nm. The gradient LC procedure was applied to seven lots of methoxsalen from five different manufacturers. Six of the seven lots tested contained isopimpinellin as the major impurity at a concentration range of 0.2-2.5%. Identification of the impurity as isopimpinellin was accomplished by a combination of analytical and preparative LC, atmospheric pressure chemical ionization liquid chromatography/mass spectrometry, and NMR.

Drug Contamination↗
PubMed1976

Phototoxicity of methoxsalen in various vehicles.

Methoxsalen (8-methoxypsoralen) was used as the photoxic substance in the study of the properties of various vehicles in photoepicutaneous testing. Macrogols as such were relatively poor bases, and positive reactions were seen only occasionally at a concentration of 0.05% methoxsalen. Increasing amounts of water in macrogols brought forth more numerous and stronger reactions. The photoxicity also increased when ethanol was added. The reactions were, however, weaker than to those with aqueous bases. Wool fat and glycerol as vehicles usually reacted in the same way as polyethylene glycols when water was added. An explanation of the mechanism of the changes in the properties of vehicles due to the addition of water/ethanol requires further investigation.

Humans↗
PubMed1976

Factors influencing methoxsalen phototoxicity in vitiliginous skin.

A series of experiments were conducted to determine the optimum conditions required to induce methoxsalen phototoxicity in vitiliginous skin. The results revealed that optimum phototoxicity could be obtained only when a lapse of at least 15 minutes was allowed between the application of the drug and exposure to long-wave ultraviolet light (UVA). The duration of methoxsalen's phototoxic potentially, after its application to skin, varied in direct proportion to chemical concentration. Although a high chemical concentration and low dosage of UVA was a less time-consuming method of inducing phototoxicity, our results indicate that lower concentration and longer UVA exposure were less likely to induce undersirable blistering reactions.

Administration, Topical↗
PubMedDate not supplied

The metabolism of 14C-methoxsalen by the dog.

Single doses of 14C-methoxsalen (5 mg/kg) were administered iv to three dogs. Almost as much administered radioactivity was excreted in the feces as in the urine, suggesting that biliary secretion of metabolites was an important route of excretion. 14C-Methoxsalen disappeared rapidly from plasma, although plasma levels of radioactivity persisted for 5 weeks after drug administration. Evidence was obtained which suggested that the persistent plasma radioactivity was due to a metabolite bound to plasma protein. Four urinary metabolites were isolated. Three of the metabolites resulted from opening of the furan ring; these are 7-hydroxy-8-methoxy-2-oxo-2H-1-benzopyran-6-acetic acid (A), alpha,7-dihydroxy-8-methoxy-2-oxo-2H-1-benzopyran-6-acetic acid (B), and an unknown conjugate of A at the 7-hydroxy position. The fourth metabolite, formed by opening of the pyrone ring, is an unknown conjugate of (Z)-3-(6-hydroxy-7-methoxybenzofuran-5-yl)-2-propenoic acid.

Animals↗
PubMed1979

Methoxsalen photochemotherapy for mycosis fungoides.

Methoxsalen photochemotherapy (PUVA; psoralen plus ultraviolet light) is effective in the treatment of mycosis fungoides (MF). The mechanism of this beneficial effect is unknown but probably involves covalent photo-binding of methoxsalen molecules to pyrimidine bases in DNA at the cellular level and impaired T-cell function or survival at the tissue level. Eleven patients (seven with plaques and four with erythroderma) were referred for PUVA therapy because of poor response to conventional therapy. Seven patients had complete clearing of skin lesions and three improved markedly. All ten of these patients experienced good to excellent control of the disease while receiving maintenance therapy, resulting in a virtual remission lasting for greater than 2 years in four patients. Of the six patients who discontinued PUVA during the followup period, three died within 1 year and three experienced progression of MF despite conventional therapy. The very promising results in this small patient group should encourage further studies of PUVA for cutaneous T-cell lymphomas.

Aged↗
PubMed1984

Mutagenicity and carcinogenicity of methoxsalen plus UV-A.

The combination of methoxsalen and long-wave UV radiation (UV-A) is being used on a large scale in clinical practice to treat a variety of dermatoses, particularly psoriasis. Theoretically, this combination may be mutagenic and carcinogenic, since methoxsalen binds covalently with DNA under the influence of UV-A. Mutagenicity has been studied in microorganisms and cell cultures. Arguments for possible carcinogenicity come from animal experiments and also from long-term follow-up studies of patients treated with psoralens and UV-A (PUVA). Transplantation studies in animals, allergic and irritative skin reaction experiments, and clinical observations indicate that PUVA also has an immunosuppressive effect. Short-term risk of skin cancer from PUVA therapy seems to be rather low if careful patient selection is made. However, for all patients, long-term maintenance treatment should be avoided as much as possible.

Animals↗
PubMed1982

GLC determination of methoxsalen in human serum and urine.

A simple, sensitive and specific GLC method for the quantitation of methoxsalen in human serum and urine is described. The procedure involves chloroformic extraction of the active ingredient and the internal standard, trioxsalen, followed by GLC determination, using flame ionization detector and 3% OV on a Gas chromosorb W column. Sensitivity was 0.1 microgram/ml and 0.2 microgram/ml for serum and urine, respectively. Methoxsalen contents of serum of rats treated with this drug are reported.

Animals↗
PubMed1976

Photochemotherapy for psoriasis with orally administered methoxsalen.

Photochemotherapy denotes a therapeutic approach that is based on the interaction of light and a photoactive drug. This study describes the efficacy of photochemotherapy, using orally administered methoxsalen and long-wave ultraviolet light in 91 patients with severe, generalized psoriasis. Oral administration of methoxsalen was followed by exposure to a high-intensity long-wave ultraviolet light source, emitting a continuous spectrum between 320 and 390 nm (peak, 365 nm) and an energy of 5.6 to 7.5 mw/sq cm at 15 cm. There was complete clearing of 82 patients (90%), a 90% to 100% clearing in seven (8%), and a satisfactory improvement in two (2%). A paired comparison study in 54 patients showed photochemotherapy to be far more effective than ultraviolet light emitted by fluorescent bulbs or a xenon source. Eighty-five percent of the patients receiving outpatient maintenance treatment have remained in remission for periods up to 400 days.

Administration, Oral↗
PubMed1977

Topical methoxsalen and blacklight in the treatment of psoriasis.

Thirty patients with recalcitrant psoriasis were treated with topical methoxsalen and blacklight (UVA). A 1% concentration either in an acetone, alcohol, propylene glycol vehicle, or hydrophilic ointment, USP, applied two hours before light exposure was highly effective. Twelve patients were completely cleared and nine were markedly improved in three to five weeks. Plaque-type and guttate psoriasis responded best while exfoliative psoriasis benefitted less. Maintenance of a phototoxic reaction in the lesion was necessary for total resolution. Topical methoxsalen and blacklight is feasible for outpatient treatment of plaque-type psoriasis of limited extent.

Administration, Topical↗
PubMed1991

Comparison of minimal phototoxic dose and skin type for determining initial UVA dose in oral liquid methoxsalen photochemotherapy for the treatment of psoriasis.

Twenty-five patients with extensive psoriasis were randomly assigned into one of three groups, each receiving 0.5 mg/kg of oral liquid methoxsalen photochemotherapy followed 1 h later by exposure to long-wave ultraviolet light (UVA). The sole difference between the three groups was the method used to determine the initial UVA dose, which was either based on skin type, 25% of the minimal phototoxic dose (MPD), or 50% of the MPD. All patients were treated in the Phototherapy Unit at the Massachusetts General Hospital. Data were obtained until reaching the endpoint of clearance. At clearance, the results of the number of treatments required to clear, final UVA dose, cumulative UVA dose, and side effects were tabulated, compared, and analyzed for each of the three groups. The 25% and 50% MPD groups required a mean of 15.0 +/- 1.7 and 13.4 +/- 1.9 treatments to clear, respectively, as compared to the skin type group, which needed an average of 17.6 +/- 2.5 treatments. The mean final UVA dose was 7.4 +/- 0.9 J/cm2 and 8.4 +/- 1.4 J/cm2 for the 25% and 50% MPD groups, respectively, in contrast to 11.6 +/- 1.4 J/cm2 for the skin type group. The mean cumulative UVA dose at clearance for the 25% and 50% MPD groups was 79 +/- 16 J/cm2 and 87 +/- 27 J/cm2, respectively, versus 136 +/- 30 J/cm2 for the skin type group. The comparisons between the individual MPD groups and the skin type group did not achieve statistical significance with the exception of a marginally significant difference in final dose between the skin type group and the 25% MPD group (p = 0.06). However, the results of the two MPD groups were then pooled and the mean final (7.9 +/- 0.8 J/cm2) and cumulative (83 +/- 15 J/cm2) UVA doses were significantly (p = 0.04) and marginally significantly (p = 0.07) lower than the respective means of the skin type group. The number of treatments to clear, although lower in the pooled MPD groups (14.2 +/- 1.3) than in the skin type group, did not attain statistical significance (p = 0.19). Our data suggest that the MPD measurement may be superior to the skin-typing system when calculating the initial UVA dose in oral liquid methoxsalen photochemotherapy for the treatment of psoriasis.

Adult↗
PubMed1979

Effect of food on kinetics of 8-methoxsalen.

Kinetics of 8-methoxsalen were studied in 5 healthy subjects under fasting and nonfasting conditions. The plasma concentration-time data could be fitted to a zero order absorption one-compartment model. The area under the curve (AUC) values were higher (p less than 0.05) under nonfasting compared to fasting conditions, indicating higher relative bioavailability of the drug in the presence of food. No significant differences were observed in the lag-time for the start of the absorption, the apparent zero-order absorption rate constant, or the elimination rate constant. It is suggested that the drug should be taken in a standardized way in relation to food during the ultraviolet (UV) light treatment.

Biological Availability↗
PubMed1979

Improved delivery of methoxsalen.

Significant improvement in the effective bioavailability of methoxsalen was achieved when it was administered to rats and dogs in a solution as compared to a suspension. Much earlier and higher peak levels were observed for the solution in both animals. The possible impact of these observations on current use of this agent for psoriasis treatment is discussed.

Administration, Oral↗
PubMed1981

Analysis of methoxsalen in plasma by reversed-phase high-performance liquid chromatography.

A high-performance liquid chromatographic method for the determination of methoxsalen in plasma was developed. The method includes extraction from plasma of the drug and the internal standard (5-methoxypsoralen) into methylene chloride. Chromatography was performed on a reversed-phase C8 column connected with a UV detector set at 254 nm. The mobile phase was methanol-acetonitrile-water (2:30:68). For a plasma sample of 0.25 ml, the maximal sensitivity was approximately 10 ng/ml. Accuracy was within 7.5% for therapeutic plasma levels, and the coefficient of variation varied between 4.3 and 0.9% for 28 and 300 ng/ml of plasma, respectively.

Chromatography, High Pressure Liquid↗
PubMed1984

Burn injury: sunlight and a single dose of methoxsalen.

A patient is described in whom burn injury, caused by moderate exposure to sunlight in the U.K., was precipitated by undue sensitivity to a photosensitizing agent methoxsalen. This drug, although withdrawn in the UK, is freely available in the Republic of Ireland and many EEC countries for the treatment of psoriasis and acne vulgaris.

Adult↗
PubMed2000

Microemulsions for topical delivery of 8-methoxsalen.

8-Methoxsalen (8-MOP) and related furocumarins have been extensively used for the treatment of hyperproliferative skin diseases in association with long-wavelength UVA light. In order to develop alternative formulations for the topical administration of 8-MOP, microemulsions were evaluated as delivery vehicles. Six microemulsion formulations were prepared using water, isopropyl myristate (IPM) and Tween((R)) 80: Span((R)) 80: 1,2-Octanediol (3:1:1.2 w/w). The microemulsions were characterized using conductimetric and dynamic light scattering analyses. The ability of the systems to deliver 8-MOP into and through the skin was evaluated in vitro using newborn pig-skin. The in vitro permeation data showed that the novel microemulsions increased the 8-MOP total penetration through the skin by order of 1.9-4.5, as compared with IPM. In general, the accumulation of 8-MOP into the skin was increased by a factor of 1.5-4.5 by the microemulsion systems with respect to their total amount of drug delivered across the skin. These results suggest that the studied microemulsion systems may be appropriate vehicles for the topical delivery of 8-MOP.

Administration, Topical↗
PubMed1986

Oral methoxsalen photochemotherapy of extensive pityriasis alba. Preliminary report.

Six patients with extensive pityriasis alba were treated with oral methoxsalen, followed by exposure to midday summer sun or exposure to long-wave ultraviolet radiation in a psoralens plus ultraviolet A (PUVA) cabinet. Complete clearing or marked improvement was obtained in five patients in less than 4 weeks of treatment. The patient with the most extensive skin involvement and the longest duration of the disease achieved a marked degree of improvement after 15 weeks of therapy. A long-term follow-up is still required to define the maintenance treatment and its efficacy.

Adult↗