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Results for “Methoxsalen”

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At least 19 recordsLinked to original sources
PubMed1979

Dermatological and ocular examinations in rabbits chronically photosensitized with methoxsalen.

Four groups of female Dutch-belted rabbits (Oryctulagus cuniculus) were given methoxsalen (12 mg/kg) or placebo by oral intubation and 1 hr later were exposed to UVA for either 2 or 8 hr. This procedure was repeated 5 days each week for 18 mo. A fifth group received no drug and no UVA exposure. The skin of the animals given methoxsalen and UVA showed signs of acute and chronic phototoxicity. Multiple peripheral blood parameters of hepatic, renal and hematologic function were normal and were not different between groups. Complete ophthalmoscopic examinations were performed periodically. No cataracts were seen in any of the animals. This data provides the perspective that in one species the daily dose of methoxsalen and UVA required to induce chronic cutaneous photosensitization is lower than the daily dose required to induce cataracts. It is inadvisable to interpret this data as suggesting that no risk exists for patients being treated with oral methoxsalen photochemotherapy. The experimental evidence supporting photosensitization as a cause of cataracts and implicating a role of lens DNA in this cataractogenesis is reviewed. Because methoxsalen-UVA alterations of lens DNA or protein could lead to delayed onset of cataracts, and because of the serious nature and potential preventability of phototoxic lens opacification, appropriate protective eye wear is recommended for all patients receiving oral psoralen photochemotherapy.

Animals↗
PubMed1977

Photochemotherapy of psoriasis using methoxsalen and sunlight. A controlled study.

Fifty-one patients with psoriasis were treated with oral methoxsalen and sunlight exposure. Twelve of these patients received either methoxsalen or placebo prior to whole-body exposure. The remainder were treated with methoxsalen and sunlight to one side of the body and sunlight alone to the other. The conventional dose of methoxsalen (0.6 mg/kg) was compared with a low dose (0.3 mg/kg). Oral methoxsalen when used in the higher dose followed by sun exposure is an effective treatment for psoriasis. Accurate ultraviolet dosimetry is essential to avoid phototoxic burns. The advantages and disadvantages of solar photochemotherapy are discussed.

Clinical Trials as Topic↗
PubMed1992

Hypocholesterolemic effect of khellin and methoxsalen in male albino rats.

Khellin (CAS 82-02-0) and methoxsalen (CAS 298-81-7) were examined in male albino rats to evaluate their ability to modify serum lipoprotein cholesterol. Clinical chemistry parameters were also measured to obtain information indicative of possible drug toxicity. The drugs were evaluated in four-week double dose studies. After four weeks at 0.45 mg/100 mg b.wt. for khellin and 0.27 mg/100 g b.wt. for methoxsalen, per day, both drugs significantly lowered low density lipoprotein cholesterol, high density lipoprotein cholesterol and total cholesterol. Very low density lipoprotein cholesterol and triglycerides were not changed. No apparent toxicity was observed as clinical chemistry parameters and body weights were not different compared to control values. Similar results were observed with a lower dose of khellin (0.23 mg/100 g b.wt./d). A dose of 0.13 mg/100 g b.wt./d of methoxsalen had no observable effect in this study. Confirmation of the hypocholesterolemic activity of khellin and methoxsalen in this study enhances the therapeutic potential of these compounds against atherosclerosis.

Animals↗
PubMed1979

Comparison of crude coal tar and topical methoxsalen in treatment of psoriasis.

Fluorescent sunlamp bulbs have been an effective light source for treatment of psoriasis when they are used in combination with crude coal tar. In addition to their ultraviolet B (UVB) emission, the spectral output of these bulbs contains a substantial amount of ultraviolet A (UVA). Prior testing with this light source and topically applied methoxsalen achieved excellent results in psoriasis. This study compared topically applied methoxsalen to crude coal tar in 16 patients who had plaque-type psoriasis, using the same fluorescent sunlamp source of irradiation. Fourteen of 16 patients had complete clearing of plaques when they were treated with methoxsalen, compared with six patients who had complete clearing with the tar treatment. These results indicate that the use of methoxsalen and ultraviolet light may be more effective than tar, when used as they were in this study. The advantages of a clean, white, nonstaining topical agent also makes outpatient therapy more cosmetically acceptable.

Coal Tar↗
PubMed1992

Comparison of the carcinogenic potential of trioxsalen bath PUVA and oral methoxsalen PUVA. A preliminary report.

BACKGROUND AND DESIGN: There is an increasing concern about the long-term carcinogenic effect of oral psoralen with long-wave UV radiation in the A range (PUVA). Most follow-up investigations indicate a definite risk of squamous cell carcinoma of the skin with long-term PUVA treatment. In a recently published study of 4799 Swedish patients who had received PUVA, it was noted that 833 patients who had received trioxsalen bath or oral trioxsalen did not show any increased risk of skin cancer in contrast to oral methoxsalen. This finding has been further investigated in this study. We compared four dermatologic university clinics in Sweden with regard to the carcinogenic potential of the PUVA regimen used. One clinic used trioxsalen bath PUVA exclusively and the other three used oral methoxsalen. Information on their PUVA-treated patients was collected and linked with information from the Swedish Cancer Registry to identify individuals with squamous cell carcinoma of the skin. RESULTS: A total of 18 squamous cell carcinomas of the skin were reported in 2975 PUVA-treated patients until 1987. The expected number was 3.1. The center using bath PUVA only had no increased risk of squamous cell carcinoma of the skin in contrast to the three centers using oral methoxsalen-PUVA. The increased risk for male subjects from those centers varied from six to 13 times that in the general population, but for female subjects a significant increased relative risk was found only at one center. CONCLUSION: In this preliminary report, PUVA treatment with trioxsalen bath seems to be less carcinogenic than the oral dosage. However, differences in the patient populations might also have affected the outcome of the study. More information on this field is needed.

Administration, Oral↗
PubMed1979

Serum concentration and phototoxic effect of methoxsalen in patients with psoriasis.

The correlation between serum concentration of methoxsalen (8-methoxypsoralen; 8-MOP) and phototoxic effect using long-wave ultraviolet light has been studied in 5 psoriatic patients. The maximum serum concentration occurred between 0.5 and 2 hr after oral administration of 0.6 mg/kg of methoxsalen. The lowest value for the minimum phototoxic dose (MPD), i.e., highest photosensitivity, was obtained between 1 and 2 hr. There was a significant negative correlation between the logarithm of the serum concentration and minimum phototoxic dose (MPD) (r = 0.780). Hence, the degree of photosensitivity appears to be related to the serum level of methoxsalen.

Adult↗
PubMed1976

Oral methoxsalen photochemotherapy of mycosis fungoides.

The cutaneous manifestations of mycosis fungoides have been successfully treated in nine patients for 16 to 28 months with oral methoxsalen and subsequent irradiation with longwave ultraviolet light. The efficacy of this therapy was confirmed in one patient, who showed complete clearing of generalized plaques after 1 month (12 treatments) except for a shielded control area which worsened during this period. Methoxsalen photochemotherapy may prove a valuable addition to therapies currently available for mycosis fungoides and may obviate some of the problems associated with conventional management of this disorder.

Administration, Oral↗
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↗
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↗
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↗
PubMed1979

Topical methoxsalen photochemotherapy in the treatment of palmoplantar pustulosis and psoriasis.

Topical methoxsalen photochemotherapy has been assessed in 22 patients suffering from recalcitrant palmoplantar pustulosis or psoriasis predominantly involving the hands and feet. Although 20 out of 22 patients improved and good results were obtained in exactly half of those treated, only 4 patients were classified as being "clear" or "minimally involved" at the end of 12 weeks. Two patients have shown no improvement at all. Minor local side effects were relatively common and included symptomatic erythema, blistering and local pigmentation. The histological findings in post PUVA treated skin are discussed and the pros and cons of topical photochemotherapy in this group of diseases is reviewed.

Administration, Topical↗