Plasma levels of 8-methoxypsoralen following oral or bath-water treatment

Improvement in Solubility-Permeability Interplay of Psoralens from Brosimum gaudichaudii Plant Extract upon Complexation with Hydroxypropyl-β-cyclodextrin

Psoralen (PSO) and 5-methoxypsoralen (5-MOP) are widely used drugs in oral photochemotherapy against vitiligo and major bioactive components of root bark extract of Brosimum gaudichaudii Trécul (EBGT), previously standardized by LC-MS. However, the exceptionally low water solubility of these psoralens can cause incomplete and variable bioavailability limiting their applications and patient adherence to treatment. Therefore, the purpose of this work was to investigate the effects of 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) inclusion complex on the solubility and jejunal permeability of PSO and 5-MOP from EBGT. Characterization of inclusion complexes were evaluated by current methods in nuclear magnetic resonance studies on aqueous solution, Fourier transform infrared spectroscopy, thermal analysis, and scanning electron microscopy in solid state. Ex vivo rat jejunal permeability was also investigated and compared for both pure psoralens and plant extract formulation over a wide HP-β-CD concentration range (2.5 to 70 mM). Phase solubility studies of the PSO- and 5-MOP-HP-β-CD inclusion complex showed 1:1 inclusion complex formation with small stability constants (Kc < 500 M−1). PSO and 5-MOP permeability rate decreased after adding HP-β-CD by 6- and 4-fold for pure standards and EBGT markers, respectively. Nevertheless, the complexation with HP-β-CD significantly improved solubility of PSO (until 10-fold) and 5-MOP (until 31-fold). As a result, the permeability drop could be overcome by solubility augmentation, implying that the HP-β-CD inclusion complexes with PSO, 5-MOP, or EBGT can be a valuable tool for designing and developing novel oral drug product formulation containing these psoralens for the treatment of vitiligo.

A quantitative mass spectrometry-based approach for assessing the repair of 8-methoxypsoralen-induced DNA interstrand cross-links and monoadducts in mammalian cells

Interstrand cross-links (ICLs) are highly toxic DNA lesions that block transcription and replication by preventing strand separation. ICL-inducing agents were among the earliest and are still the most widely used forms of chemotherapeutic drugs. Because of the repair of DNA ICLs, the therapeutic efficacy of the DNA cross-linking agents is often reduced by the development of chemoresistance in patients. Thus, it is very important to understand how various DNA ICLs are repaired. Such studies are currently hampered by the lack of an analytical method for monitoring directly the repair of DNA ICLs in cells. Here we report a high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method, together with the isotope dilution technique, for assessing the repair of 8-methoxypsoralen (8-MOP)-induced DNA ICLs, as well as monoadducts (MAs), in cultured mammalian cells. We found that, while there were substantial decreases in the levels of ICL and MAs in repair-competent cells 24 h after 8-MOP/UVA treatment, there was little repair of 8-MOP-ICLs and -MAs in xeroderma pigmentosum, complementation group A-deficient human skin fibroblasts and excision repair cross-complementing rodent repair deficiency, complementation group 1-deficient Chinese hamster ovary cells over a 24 h period. This result provided unequivocal evidence supporting the notion that the 8-MOP photoadducts are substrates for nucleotide excision repair in mammalian cells. This is one of the first few reports about the application of LC-MS/MS for assessing the repair of DNA ICLs. The analytical method developed here, when combined with genetic manipulation, will also facilitate the assessment of the roles of other DNA repair pathways in removing these DNA lesions, and the method can also be generally applicable for investigating the repair of other types of DNA ICLs in mammalian cells.

PUVA-gel vs. PUVA-bath therapy for severe recalcitrant palmoplantar dermatoses. A randomized, single-blinded prospective study

BACKGROUND/PURPOSE

In order to avoid unwanted effects of systemic psoralen and ultraviolet A (PUVA) therapy, various topical PUVA treatment modalities have been developed and are being increasingly used. However, up to now very few controlled studies comparing the therapeutic efficacy of different topical photochemotherapy modalities are available. Thus, the aim of our study was to compare the clinical efficacy of conventional PUVA-bath therapy to topical PUVA-gel therapy in patients with recalcitrant dermatoses of the palms and soles.

METHODS

Twenty patients with severe palmoplantar dermatoses or localized psoriatic plaques were enrolled in our observer-blinded, randomized half-sided study. The treatment modalities compared were: (i) aqueous 8-methoxypsoralen (8-MOP)-containing gel plus broadband UVA irradiation (PUVA-gel therapy) and (ii) 8-MOP bath of the hands and/or feet plus broadband UVA (PUVA-bath therapy).

RESULTS

On the body half, which was randomized to PUVA-gel therapy, the median Area and Severity Index for palmoplantar dermatoses (ASIppd) decreased from 28 (range 6-56) to 1.5 (range 1-37, P = 0.00) after a median 33 (13-49) irradiations compared with a reduction from 26.5 (range 6-52.5) to 1.5 (range 0-38, P = 0.00) for PUVA-bath therapy. Both improvements of ASIppd scores were found to be statistically significant, with no significant difference between PUVA-gel and PUVA-bath therapy. Severe phototoxic reactions such as strong erythema, blistering and/or pain were not observed in any patient.

CONCLUSION

PUVA-gel therapy seems to be an effective therapeutic alternative to conventional PUVA-bath therapy in treating localized dermatoses of the palms and soles. The advantage of PUVA-gel therapy is reduced organizational efforts and expenses.

Determination of 8-methoxypsoralen in human plasma, and microdialysates using liquid chromatography–tandem mass spectrometry

The validation of a LC/MS/MS method for the determination of 8-methoxypsoralen (8-MOP) in human plasma and microdialysates after topical application is described. Plasma samples were extracted by liquid-liquid extraction with diisopropylether using 4,5',8-trimethylpsoralen (TMP) as internal standard. Chromatographic separation of plasma sample extracts was carried out using a short narrow-bore Nucleosil C18 column (30 mm x 2.0 mm i.d.) with acetonitrile/(2 mM ammonium acetate buffer, 2 mM acetic acid) (80:20, v/v). For mass spectrometric analysis an API 3000 triple quadrupole mass spectrometer was employed. The mass transitions used were m/z 217.2-->174.0 for 8-MOP and m/z 229.1-->142.1 for TMP. Microdialysis samples diluted with an equal amount of acetonitrile did not require any extraction and were analyzed directly on a narrow-bore Nucleosil C18 column (70 mm x 2.0mm i.d.) with acetonitrile/(2 mM ammonium acetate buffer, 2 mM acetic acid) (50:50, v/v) with the mass transition m/z 217.2-->174.0. The assays were validated over the concentration ranges of 0.5-50 ng/ml for plasma samples and 0.25-50 ng/ml for microdialysates, respectively.

Correlation between 8-methoxypsoralen bath-water concentration and photosensitivity in bath-PUVA treatment

BACKGROUND

Bath-PUVA treatment, originally established in Scandinavia, offers several advantages over oral PUVA and has become increasingly popular in recent years. Outside Scandinavia 8-methoxypsoralen (8-MOP) is the prevailing photosensitizer for this PUVA modality and is used arbitrarily in a wide range of concentrations. Up to the present, data are lacking on the impact of 8-MOP bath-water concentration on UVA dosimetry.

OBJECTIVE

We investigated the influence of increasing 8-MOP bath-water concentrations on photosensitivity in bath-PUVA treatment.

METHODS

Fifteen healthy volunteers without abnormal photosensitivity or recent exposure to ultraviolet radiation were included in an intraindividually controlled comparison study. In all volunteers the minimal phototoxic dose (MPD) was determined on the volar side of their forearms after immersion for 20 minutes in 4 different 8-MOP bath-water concentrations (0.5, 1, 2.5, and 5 mg/L). The correlation between 8-MOP concentration and photosensitivity (defined as the reciprocal value of the MPD) was analyzed by linear regression analysis. In addition, the time course of erythema formation and the UVA dose-erythema response curve was assessed for each psoralen concentration.

RESULTS

The median MPD and the 25%-75% interquartile were 5.7 J/cm(2) (5.7-8), 4 J/cm(2) (4-5.7), 2.8 J/cm(2) (2.8-5.7), and 2 J/cm(2) (2-2.8) at an 8-MOP concentration of 0.5, 1, 2.5, and 5 mg/L, respectively. Linear regression analysis revealed a significant correlation between 8-MOP bath-water concentration and photosensitivity (r = 0.98; P =.019). Bath-PUVA-induced erythema peaked after a median time interval of 3 days, with a range of 2 to 4 days. The slope of the UVA dose-erythema response curve was similar for all psoralen concentrations.

CONCLUSION

UVA dose requirements in bath-PUVA treatment decrease linearly with increasing 8-MOP concentrations. A single MPD assessment at 72 hours after the UVA exposure is inappropriate for accurate determination of the patients' photosensitivity. The hazard of wrong UVA dosimetry is comparable at all psoralen concentrations.

Concentration-dependent phototoxicity in trimethylpsoralen bath psoralen ultraviolet A

BACKGROUND

Long-term use of topical trimethylpsoralen (TMP) psoralen bath plus ultraviolet A (bath PUVA) is considered safe with regard to the risk of skin cancer. However, the potential for severe phototoxicity limits its use.

OBJECTIVES

To study the effect of dilution of the TMP bath on the minimal phototoxic dose (MPD).

METHODS

Fifteen volunteers participated in the study. The MPD tests were performed for three TMP concentrations: 0.33 mg L-1, 0.1 mg L-1 and 0.033 mg L-1 at 2-week intervals. Geometric UVA dose series increasing by a factor of radical2 were used for the testing on the previously unexposed buttock skin. The MPD72 h was assessed at 72 h from the bath.

RESULTS

For the highest TMP concentration of 0.33 mg L-1, the median MPD72 h was 0.14 J cm-2 (95% confidence interval (CI), 0.10-0.14 J cm-2). For the diluted TMP bath concentration of 0.1 mg L-1, the median MPD72 h increased to 0.29 J cm-2 (95% CI, 0.2-0.41 J cm-2) and for 0.033 mg L-1 to 0.81 J cm-2 (95% CI, 0.57-1.15 J cm-2), respectively. Thus, diluting the labelled concentration of 0.33 mg L-1 1 : 10 increased the median MPD72 h 5.6-fold.

CONCLUSIONS

With regard to the safety and practicality of the TMP bath PUVA, the lower concentrations of TMP may be of clinical importance, and this needs to be validated in future controlled clinical trials.

A comparison of bathwater and oral delivery of 8-methoxypsoralen in PUVA therapy for plaque psoriasis

Bath-PUVA is an alternative to oral-PUVA for the treatment of psoriasis. This study compares the effectiveness of the two methods in two groups, each consisting of 17 patients with plaque psoriasis. Three patients who failed to improve with oral-PUVA were transferred to bath-PUVA and subsequently cleared. Another seven patients who returned with a further episode of psoriasis received the alternative treatment; this gave a group of 10 patients in whom a cross-over comparison was possible. In both comparisons bath-PUVA was as effective as, or more effective than, oral-PUVA and required, overall, less than 50% of the total UVA, although this saving was not as great as in previous reports. Bath-PUVA caused fewer immediate problems and was preferred by many patients. It is suitable for those taking other systemic medications and we recommend it as a valuable therapeutic option that should be available at all treatment centres.

Guidelines for topical PUVA: a report of a workshop of the British photodermatology group

Psoralen photochemotherapy [psoralen ultraviolet A (PUVA)] plays an important part in dermatological therapeutics, being an effective and generally safe treatment for psoriasis and other dermatoses. In order to maintain optimal efficacy and safety, guidelines concerning best practice should be available to operators and supervisors. The British Photodermatology Group (BPG) have previously published recommendations on PUVA, including UVA dosimetry and calibration, patient pretreatment assessment, indications and contraindications, and the management of adverse reactions.1 While most current knowledge relates to oral PUVA, the use of topical PUVA regimens is also popular and presents a number of questions peculiar to this modality, including the choice of psoralen, formulation, method of application, optimal timing of treatment, UVA regimens and relative benefits or risks as compared with oral PUVA. Bath PUVA, i.e. generalized immersion, is the most frequently used modality of topical treatment, practised by about 100 centres in the U.K., while other topical preparations tend to be used for localized diseases such as those affecting the hands and feet. This paper is the product of a recent workshop of the BPG and includes guidelines for bath, local immersion and other topical PUVA. These recommendations are based, where possible, on the results of controlled studies, or otherwise on the consensus view on current practice.

PUVA-bath photochemotherapy (PUVA-soak therapy) of recalcitrant dermatoses of the palms and soles

PUVA-bath therapy has proven to avoid many side effects associated with oral 8-methoxypsoralen (8-MOP) treatment. In order to investigate the effectiveness of topical PUVA-bath therapy (PUVA-soak therapy) on chronic palmoplantar dermatoses, 30 patients with plaque-type psoriasis, pustular psoriasis, endogenous eczema, dyshidrotic eczema and hyperkeratotic dermatitis of the palms and soles were treated over 8 weeks with PUVA-soak using 8-MOP. No additional treatment except skin moisturising cream such as unguentum emulsificans aquosum was used during the study period. The single UVA-doses applied ranged from 0.3 to 3.0 J/cm2 (mean single dose of 1.8 J/cm2), with a mean cumulative dose of 48.6 J/cm2 per patient. Altogether 26 of 30 patients responded well within 8 weeks of treatment with 63% of all patients showing a complete remission and 23% showing considerable improvement, as shown by flattening of plaques, decreased scaling and erythema, as well as decreased vesicle and pustule formation. The condition responding best to our therapy was palmoplantar psoriasis followed by atopic eczema. Hyperkeratotic dermatitis displayed the poorest responding rates in this study. Unwanted side effects such as erythema, pain, blistering or patchy hyperpigmentation were not observed in any of the patients. We conclude that PUVA-soak therapy can be highly efficient in the treatment of palmoplantar dermatoses, especially in the management of palmoplantar psoriasis.

Plasma levels of 8-methoxypsoralen following PUVA-bath photochemotherapy

Administration of 8-methoxypsoralen (8-MOP) in a dilute bath water solution is an effective therapeutic alternative to oral PUVA therapy, avoiding systemic side effects, offering better bioavailability of the psoralen and requiring much smaller amounts of UVA for induction of therapeutic effects. To obtain exact data about the percutaneous absorption of 8-MOP during a psoralen bath, the plasma levels of the drug were determined in 26 patients with different skin diseases by a reverse high-performance liquid chromatographic method. Fifteen patients receiving oral PUVA therapy (0.8 mg 8-MOP/kg body weight) served as a positive control group. Bath solutions were prepared by diluting 15 ml of 0.5% stock solution of 8-MOP in 150 l of bath water (0.5 mg/l, 37 degrees C). Blood samples were drawn from patients 5, 30, 60, 120 and 180 min after the bath. In the oral PUVA group, blood samples were obtained 1 1/2 h after administration of the drug. In 23 of 26 patients, 8-MOP levels were undetectable in every blood sample. After 30 min, two patients showed detectable levels of 8-MOP (5 ng/ml, 7 ng/ml), while 60 min after the PUVA bath 8-MOP was detectable in only one volunteer (5 ng/ml). In patients receiving oral 8-MOP therapy, serum levels varied between 45 and 360 ng/ml 1 1/2 h after drug administration. Our data confirm extremely low 8-MOP levels resulting from 8-MOP bath water treatments and provide confirmation of the absence of systemic side effects in patients who are undergoing PUVA-bath therapy.

Topical psoralen-ultraviolet A therapy for palmoplantar dermatoses: experience with 35 consecutive patients

OBJECTIVE

To report the effectiveness of topical psoralen-ultraviolet A (PUVA) therapy for palmoplantar dermatoses and to describe our method of administration of this treatment modality.

DESIGN

We conducted a retrospective study of 35 patients, 27 to 66 years of age, who received topical hand and foot PUVA therapy.

MATERIAL AND METHODS

Ten patients had psoriasis vulgaris, 8 had pustular psoriasis, 5 had dyshidrotic eczema, and 12 had other types of dermatitis. The affected area was soaked in a psoralen solution, 0.0005% methoxsalen (10 mg of methoxsalen in 2 L of warm water), for 30 minutes and then exposed to incremental amounts of ultraviolet A light three times weekly until the dermatosis subsided or cleared. Treatment frequency was then reduced and ultimately discontinued. Time to maximal improvement of the hands and feet was defined as the period from the beginning of PUVA treatment to the point at which the frequency of treatment was reduced from three times weekly to twice weekly.

RESULTS

Fourteen patients (40%) had clearing of their disease, and 14 others (40%) had improvement of their conditions. The mean time to clearing was 2.8 months (range, 2 weeks to 7 months), and the mean number of treatments was 27.3 (range, 10 to 55). The mean total dose of ultraviolet A received was 140 J/cm2 (range, 9 to 530). Two patients (6%) had no response to treatment. Mild localized ultraviolet-related erythema developed in 16 patients (46%). Five patients "dropped out" of treatment, and nine other patients discontinued treatment during maintenance therapy. The principal reason cited was inconvenience.

CONCLUSION

Topical PUVA therapy is an effective and safe treatment option for recalcitrant dermatoses affecting the palms and soles.

Treatment of chronic palmoplantar eczema with local bath-PUVA therapy

BACKGROUND

Systemic PUVA therapy may be useful in the treatment of chronic palmoplantar eczema. Topical PUVA-paint avoids some of the unwanted side effects of systemic psoralens and has been used successfully in the treatment of palmoplantar eczema and psoriasis. However, few data are available on the effectiveness of local bath-PUVA therapy in palmoplantar eczema.

OBJECTIVE

Our purpose was to assess the effectiveness of local bath-PUVA therapy in 28 patients with chronic palmar or plantar eczema or both who were resistant to conventional topical treatment.

METHODS

After fungal or bacterial infection had been excluded in all patients, hands or feet or both were soaked for 15 minutes in warm water containing 1 mg/L 8-methoxypsoralen. Immediately after, the skin was irradiated with increasing doses of UVA, starting with 0.5 J/cm2. PUVA-bath therapy was performed 4 times a week up to a total of 25 treatments. No additional therapy was allowed except emollients.

RESULTS

Excellent or good effects were achieved in 93% of the patients with dyshidrotic and in 86% of the patients with hyperkeratotic eczema. In the patients with dyshidrotic eczema, the cumulative doses and the highest single doses of UVA were lower than those in the patients with hyperkeratotic eczema (21.4 vs 27.9 J/cm2 and 2.4 vs 3.0 J/cm2 of UVA), but this was not statistically significant. No phototoxic reactions were observed.

CONCLUSION

Local bath-PUVA therapy is of value in the management of chronic palmoplantar eczema resistant to standard modes of topical treatment. Compared with topical PUVA-paint, local bath-PUVA therapy has several advantages, particularly the absence of phototoxic reactions, severe hyperpigmentation, and protracted photosensitivity.

Treatment of psoriasis with polyethylene sheet bath PUVA

BACKGROUND

Bath PUVA has been shown to be an effective alternative treatment for psoriasis with fewer systemic side effects than oral methoxsalen (8-MOP). The cost of 8-MOP and the need for a bath unit have prevented wider use of this treatment.

OBJECTIVE

We investigated the safety and efficacy of sheet bath PUVA by restricting the volume of the psoralen/bath water solution to 10 L with the aid of a polyethylene sheet.

METHODS

Fifty-eight patients with chronic plaque-type psoriasis were treated with bath PUVA in a concentration of 0.5 mg of 8-MOP per liter of water.

RESULTS

The group required a median of 17 baths (95% confidence interval [CI], 14-20) for clearance. Total UVA dose for the entire group was 26 J/cm2(95% CI, 18-47).

CONCLUSION

Sheet bath PUVA is safe, efficient, and easy. This regimen can significantly reduce the amount of 8-MOP required, thereby resulting in a favorable cost/benefit ratio.

Permeation characteristics of 8-methoxypsoralen through human skin; relevance to clinical treatment

The permeation characteristics through human skin of 8-methoxypsoralen (8-MOP) and its physical attributes were investigated. The log octanol/water partition coefficient and saturated aqueous solubility of 8-MOP at 32 degrees C were 1-98 and 55.8 micrograms mL-1 respectively, 8-MOP showed Fickian diffusion, with its flux being linearly related to the concentration of drug in the donor solution. The permeability coefficient of 8-MOP through human skin from different concentrations of aqueous solutions and a 2.6 micrograms mL-1 bath lotion (as used in clinics) were statistically identical with mean values of 1.76 +/- 0.12 x 10(-2) and 1.70 +/- 0.32 x 10(-2) cm h-1 respectively (P > or = 0.05). An ethanol/water (1:1 w/v) receptor solution did not improve the clearance of 8-MOP from the dermis when compared with an aqueous vehicle. Complete removal of the stratum corneum by tape stripping from full-thickness membranes produced a threefold increase in the flux of 8-MOP thus suggesting that the main barrier to 8-MOP permeation resides in the stratum corneum although the aqueous epidermal and dermal tissue provide a significant resistance to transdermal drug permeation. The equilibrium uptake of 8-MOP into psoriatic plaques and the 8-MOP aqueous plaque partition coefficient were found to be more than twofold greater than for normal stratum corneum. The absorption of 8-MOP from the total applied topical dose (396 mg) was assessed as approximately 0.25% and only 2.5% of an oral dose, a significant reduction in the possible toxic hazard. The peak concentration of 8-MOP permeating through the skin was observed at about 35 min after limited exposure for 15 min. Our results suggest that following a 15 min bath in the drug solution, there may be a need for an interval of about 20 min before patients are irradiated to ensure the optimization of photosensitizer with UVA irradiation (PUVA) therapy. Alternatively, UV irradiation could be applied at a lower flux over a longer time.

Plasma levels of 8-methoxypsoralen after bath-PUVA for psoriasis: relationship to disease severity

Plasma levels of 8-methoxypsoralen (8-MOP) were determined by high-pressure liquid chromatography in 19 patients with psoriasis who were receiving bath-PUVA treatment, at different time points after the psoralen bath. The levels of 8-MOP varied between < 5 ng/ml (lower limit of detection) and 34 ng/ml, and we found a relationship between the plasma psoralen levels and the severity of the disease.

Plasma levels of 8-methoxypsoralen after topical paint PUVA

BACKGROUND

Topical PUVA therapy has become a useful alternative for patients who cannot tolerate the systemic side effects of nausea and headache or are concerned about the ophthalmologic risk associated with oral PUVA therapy. However, there is no study to date on the systemic absorption of psoralen after the localized application of topical paint PUVA.

OBJECTIVE

This study was designed to assess the plasma level of 8-methoxypsoralen (8-MOP) after paint PUVA therapy for patients with palmoplantar psoriasis or eczema.

METHODS

Reverse-phase high-pressure liquid chromatography was used to determine 8-MOP plasma levels in eight patients with palmoplantar psoriasis and two with eczema. Three patients receiving oral PUVA therapy served as the control group.

RESULTS

Plasma levels of 8-MOP taken 1, 6, and 24 hours after topical PUVA treatments of patients with palmoplantar psoriasis were undetectable. One patient with hand eczema consistently had detectable 8-MOP levels 1 hour after topical PUVA treatments.

CONCLUSION

This report indicates that there is minimal, if any, systemic absorption of 8-MOP after topical PUVA treatment of patients with palmoplantar psoriasis.

Bath-water compared with oral delivery of 8-methoxypsoralen PUVA therapy for chronic plaque psoriasis

Forty-four patients with chronic plaque psoriasis were randomly allocated to treatment with bath-water-delivered 8-methoxypsoralen (bath 8-MOP) or oral 8-methoxypsoralen (oral 8-MOP) PUVA therapy. There was a significant reduction in extent of the lesions and psoriasis area and severity index (PASI) after 20 treatments with each modality. There was a fourfold reduction in cumulative ultraviolet A (UVA) dose in the bath group. Side-effects of erythema and nausea were less with bath therapy.