Nationwide survey on family caregiver-perceived experiences of patients with cancer of unknown primary site.

PURPOSE: Cancer of unknown primary site (CUP) is an aggressive disease with poor prognosis. As research on the experiences of CUP patients and their families is scarce, this study aimed to compare the family caregiver-perceived burden of CUP with that of common cancers (lung, colon, and stomach cancers). The association between family caregiver-perceived burden and CUP patients' quality of life (QOL) at end-of-life and family depression, respectively, was also explored. METHODS: This was a pre-planned secondary analysis of nationwide cross-sectional survey data from the bereaved family caregivers of patients with cancer who died at 286 institutions. The major measurements were the eight-item family caregiver-perceived Burden scale (comprising specialist access, uncertainty, and prolonged diagnosis), Good Death Inventory, and Patient Health Questionnaire 9. RESULTS: Of 27,591 survey responses, we analyzed 97 and 717 responses from family caregivers of patients with CUP and common cancer, respectively. The families of CUP patients scored significantly higher on all three burden subscales than those of common cancer patients (effect sizes: specialist access subscale, 0.3; uncertainty subscale, 0.66; and prolonged diagnosis subscale, 0.69; adjusted P < 0.01). Greater family burden was significantly associated with lower patient QOL and higher family depression. Burden was significantly associated with being a spouse, second opinion consultation, and diagnosis period of > 1 month. CONCLUSION: The family caregivers of CUP patients experience poor specialist access, greater uncertainty, and a prolonged diagnosis. They should be cared for from the initial stages to establish access to specialists, obtain an early diagnosis, and reduce uncertainty.

Private or shared room? A nationwide questionnaire survey on bereaved family members' perceptions of where patients spend their last days.

BACKGROUND: Where patients receive end-of-life care influences their quality of life. OBJECTIVES: To clarify the effects of staying in a private or shared room in inpatient hospices. DESIGN: A part of a Japanese multicentre survey to evaluate the quality of end-of-life care. SETTING/PARTICIPANTS: 779 bereaved families whose relatives who died from cancer in inpatient hospices. MEASUREMENTS: The primary outcome was family-perceived need for improvement in environment-related professional care. Secondary end-points included: family satisfaction, environment-related family perception, and quality of death and dying (Good Death Inventory: GDI). RESULTS: 574 responded (73.7%). 300 patients were in a private room from admission to discharge, 47 were in a shared room less than 50% of the time, and the remaining 85 were in a shared room 50% or more. There were significant differences in the need for improvement in shared (vs private) rooms, and in favour of private rooms for: 'privacy was protected', 'easy for visitors to visit', 'could discuss sensitive issues with medical staff without concern', and 'could visit at night.', as well as 'living in calm circumstances' and 'spending enough time with family' of the GDI. Contrarily, significant differences were found in favour of shared rooms for: 'the patient could interact with other patients'. There was no significant difference in family satisfaction and total score of GDI. CONCLUSION: There are the advantages and disadvantages of spending one's final days in a private or shared room, and adjusting rooms according to patients and their families' values is necessary.

Influence of financial burden on withdrawal or change of cancer treatment in Japan: results of a bereavement survey.

PURPOSE: This study aimed to examine the effect of financial burden of cancer treatment from diagnosis to end-of-life on treatment withdrawal or change in Japan. METHODS: This study was part of a nationwide survey of bereaved family members of cancer patients in Japan (J-HOPE2016 study). Questions regarding withdrawal or change of cancer treatment (stratified according to whether the treatment was recommended by physicians or based on the patients' request), financial difficulties in coping with cancer treatment expenses, and the participants' socioeconomic background were asked. Descriptive analyses were performed, and logistic regression was used to examine the factors related to withdrawal or change of cancer treatment. RESULTS: In total, 510 (60%) questionnaires were returned. Approximately 7.5% of participants reported withdrawal or change of cancer treatment for financial reasons. Financial difficulties in coping with cancer treatment expenses such as using up all or a portion of one's savings (OR = 2.14, 95% CI = 1.14-4.04, p = 0.018/ OR = 3.45, 95% CI = 1.52-7.81, p = 0.003) and subjective financial burden (OR = 2.54, 95% CI = 1.25-5.14, p = 0.010/OR = 3.89, 95% CI = 1.68-9.00, p = 0.002) were significantly related to withdrawal or change of cancer treatment (recommended by physicians/based on patient request). CONCLUSION: Fewer participants reported withdrawal or change of cancer treatment than in previous studies, which might reflect the characteristics of the Japanese healthcare system. However, there are patients in Japan who withdraw or change cancer treatment for financial reasons. Medical staff should consider financial toxicity as a serious side effect and assist patients in their decision-making regarding treatment while taking into account their socioeconomic backgrounds.

Are cancer patients living alone more or less likely to achieve a good death? Two cross-sectional surveys of bereaved families.

This study examined differences in sociodemographic characteristics and the achievement of a good death between cancer patients who live alone and those who do not live alone prior to death in different settings. Secondary analysis of data collected across two cross-sectional self-reported questionnaire surveys was undertaken. The participants were bereaved family members of cancer patients who had died in palliative care units (PCUs), acute hospitals or homes. We stratified the data by the place of death and examined the differences in sociodemographic characteristics to determine the relationship between cancer patients achieving a "good death" and whether they were living alone. The data were collected through 15,949 surveys. On the Good Death Inventory, significantly higher total scores emerged for cancer patients who were living alone than for those who not living alone in PCUs (effect size [ES] = 0.11, Student's t-test: p < .0001), but not in acute hospitals (ES = -0.03, p = 0.74) or home care services (ES = 0.02, p = 0.86). Cancer patients who were living alone were more likely to have been female, been older and have earned a lower annual income than those who were not living alone. Thus, among those who had received specialized palliative care, there was no difference in the quality of palliative care between cancer patients who were or were not living alone.

Effects of financial status on major depressive disorder and complicated grief among bereaved family members of patients with cancer.

OBJECTIVE: To examine current financial status, changes before and after bereavement, and their effects on possible major depressive disorder (MDD) and complicated grief (CG) among bereaved family members of patients with cancer. METHODS: We conducted a nationwide cross-sectional questionnaire survey on 787 bereaved family members of patients with cancer in 71 palliative care institutions in Japan from May to July 2016. The survey assessed perceived level of concern regarding current financial status and whether it changed after bereavement. We also collected information on demographic factors and assessed the possible MDD and CG using the Patient Health Questionnaire-9 and Brief Grief Questionnaire, respectively. We then conducted bivariate analysis to examine the relationship between these factors and financial status. RESULTS: A total of 491 (62%) questionnaires were returned. The majority of the participants (n = 382, 78%) reported having no or mild concerns about their livelihood, whereas 19% (n = 95) had moderate to severe concerns. Regarding the change in financial status after bereavement, 7% (n = 35) reported improvement, 28% (n = 131) reported worsening, and 65% (n = 308) reported no change. The prevalences of possible MDD and CG were 22% (n = 108) and 9% (n = 41), respectively, and were significantly lower among participants with less concern regarding their livelihood and whose financial status had not changed after bereavement (both p < 0.05). CONCLUSIONS: About one-fifth of the bereaved family members reported financial difficulties to some extent; these were significantly associated with MDD and CG. These findings provide evidence of the need for psychosocial support including financial consultation for bereaved family members.

Defining a good death for people with dementia: A scoping review.

AIM: End-of-life care for people with dementia is becoming increasingly important as the global population ages. However, there is no agreed definition of a good death for people with dementia. The current review examined previous literature to establish the current state of knowledge on this issue. METHODS: We conducted a scoping review using a standard methodological framework. Relevant studies were identified from four databases. Studies were included if they were in English, discussed palliative or end-of-life care for dementia, and defined or explained a good death. The definitions or explanations of a good death were categorized into subthemes, and grouped into broader themes. RESULTS: We identified 11 articles discussing or explaining a good death in dementia, which were published between 2009 and 2017. Most of these studies drew on the views of healthcare professionals and/or family members of people with dementia, and only one considered the views of people with dementia themselves. Ten themes were identified, including pain-free status, peaceful/comfort, dignity, family presence, surrounded by familiar things and people, person-centered communication, spirituality, life completion, treatment preferences, and other. CONCLUSIONS: The characteristics of a good death in dementia showed similarities with those identified more generally. However, there were some themes that were specific to end-of-life care in dementia, notably "surrounded by familiar things and people" and "person-centered communication". To obtain a fuller picture of the nature of a good death in dementia, researchers need to examine the views of people living with dementia.

Development and validation of the Terminal Delirium-Related Distress Scale to assess irreversible terminal delirium.

OBJECTIVE: There is no tool to appropriately assess terminal delirium, including the natural terminal course. The objective of this study was to develop an evaluation scale to assess distress from irreversible terminal delirium and to examine the validity of the scale. METHOD: Based on previous qualitative analysis and systematic literature searches, we carried out a survey regarding the views of bereaved families and developed a questionnaire. We extracted items that bereaved families regarded as important and constructed an evaluation scale of terminal delirium. Then, we applied the questionnaire in a cross-sectional questionnaire survey of bereaved relatives of cancer patients who were admitted to a hospice or a palliative care unit. RESULTS: We developed the Terminal Delirium-Related Distress Scale (TDDS), a 24 item questionnaire consisting of five subscales (support for families and respect for a patient, ability to communicate, hallucinations and delusions, adequate information about the treatment of delirium, and agitation and restlessness). Two hundred and eighty-one bereaved relatives participated in the validation phase. The construct validity was shown to be good by repeated factor analysis. Convergent validity, confirmed by the correlation between the TDDS and the Care Evaluation Scale (r = 0.651, P < 0.001), was also good. The TDDS had good internal consistency (Cronbach's alpha coefficient for all 24 items = 0.84). SIGNIFICANCE OF RESULTS: This study showed that the TDDS is a valid and feasible measure of irreversible terminal delirium.

The association of family functioning and psychological distress in the bereaved families of patients with advanced cancer: a nationwide survey of bereaved family members.

OBJECTIVES: Family conflict and family functioning were regarded as changeable factors associated with complicated grief (CG) and major depressive disorder (MDD) in the bereaved families of patients with advanced cancer, although the evidence is limited. We explored the family functioning associated with CG and MDD developing either independently or co-morbidly in the bereaved families of patients with advanced cancer who died in palliative care units (PCUs). METHODS: This study comprised a nationwide cross-sectional questionnaire survey of bereaved family members of cancer patients who died in Japanese PCUs participating in evaluation of the quality of end-of-life care. RESULTS: A total of 529 questionnaires (69.2%) were returned, and we analyzed a total of 458 responses. A total of 14.2% of participants were considered as having CG, 22.5% as having moderate to severe depression, and 9.6% as having co-morbid symptoms. Multivariate logistic regression analysis revealed that many family members insulted or yelled at one another (odd ratio [OR]: 2.99, p = 0.046; OR:2.57, p = 0.033), and conflict regarding what is meant by a good death (OR:3.60, p = 0.026; OR:4.06, p = 0.004) was significantly positively associated with CG, MDD, and co-morbid symptom. CONCLUSIONS: Specific family conflicts may increase the incidence of CG, MDD, and co-morbid symptoms in the bereaved families of patients with advanced cancer. Our results may encourage health care providers to approach discussions about end-of-life issue with the patient and their family in advance, especially focusing on what is considered a good death for the patient, which may prevent or resolve the family conflict.

Comparison of two measures for Complicated Grief: Brief Grief Questionnaire (BGQ) and Inventory of Complicated Grief (ICG).

OBJECTIVE: No prior studies have used a single sample of bereaved families of cancer patients to compare multiple scales for assessing Complicated Grief. Here, we compare the two measures. METHODS: We sent a questionnaire to the bereaved families of cancer patients who had died at 71 palliative care units nationwide. RESULTS: The analysis included 3173 returned questionnaires. Prevalence of Complicated Grief was 7.8% by Brief Grief Questionnaire (with a cutoff score of 8) and 15.5% for Inventory of Complicated Grief (with a cutoff score of 26). The Spearman's correlation coefficient between the Brief Grief Questionnaire and the Inventory of Complicated Grief was 0.79, and a ceiling effect was seen for the distribution of the Brief Grief Questionnaire scores. Although 6.4% of respondents scored both 8 or higher on the Brief Grief Questionnaire and 26 or higher on the Inventory of Complicated Grief, only 1.4% scored both 8 or higher on the Brief Grief Questionnaire and <26 on the Inventory of Complicated Grief. In contrast, 9.1% scored <8 on the Brief Grief Questionnaire but 26 or higher on the Inventory of Complicated Grief. CONCLUSION: The prevalence of Complicated Grief was estimated to be higher by the Inventory of Complicated Grief than by the Brief Grief Questionnaire in this sample. Patients with severe Complicated Grief might be difficult to discriminate their intensity of grief by the Brief Grief Questionnaire. Once the diagnostic criteria of Complicated Grief are established, further research, such as optimization of cutoff points and calculations of sensitivity and specificity, will be necessary.

A Nationwide Survey of Bereaved Family Members' Perception of the Place Patients Spent Their Final Days: Is the Inpatient Hospice Like or Unlike a Home? Why?

Background: During end-of-life care, the place in which the patients spend time influences their quality of life. Objective: To clarify what it means to spend last days at home and in inpatient hospice. Design: This study was a part of a nationwide multicenter questionnaire survey of bereaved family members of cancer patients evaluating the quality of end-of-life care in Japan. Setting/Subjects: A nationwide questionnaire survey was conducted with 779 family members of cancer patients who had died at inpatient hospices. We asked participants about the perceived benefits of spending last days at home and inpatient hospice during the patient's last days. Measurements: A nationwide questionnaire. Results: Of participants, 37.6% (n = 185 [95% confidence interval, 33%-42%]) felt that the inpatient hospice was like a home. The family members who reported that the inpatient hospice felt like home significantly tended to report high satisfaction with the level of care (p < 0.01). Factors that the participants perceived as benefits of the inpatient hospice were: "If anything changes, as health care professionals are easily available, he/she can handle it" (88.1%), "he/she is reassured" (78.4%), and "he/she is safe" (72.7%). On the contrary, factors that they perceived as benefits of home were: "He/she can do what he/she wants to do without worrying about the eye of other people" (44.1%), "he/she can relax" (43.5%), and "he/she is free" (42.0%). Conclusions: Spending the last days of life in either an inpatient hospice or at home has specific benefits. The place a patient spends his/her end-of-life days should be based on patient and family values.

Communication about the impending death of patients with cancer to the family: a nationwide survey.

OBJECTIVES: Explanation about the impending death of imminently dying patients with cancer is important for their families. However, little is known about how clinicians explain impending death and how families perceive the explanation. We aimed to clarify bereaved families' perception of the need for improvements in the explanation about impending death and to explore the factors contributing to the need. METHODS: In a nationwide survey of 818 bereaved families of patients with cancer admitted to inpatient hospices in Japan, we evaluated family-perceived need for improvements in the explanation about impending death and families' experiences of the explanation. RESULTS: Among all the participants (n=516, 63%), 35 (6.8%), 123 (24%) and 297 (58%) families felt that much/considerable, some and no improvements were needed, respectively. Independent determinants of the need were a younger patient age (OR=0.97; 95% CI 0.95 to 0.99; P=0.009); not receiving an 'explicit explanation about physical signs of impending death' (OR=0.67; 95% CI 0.51 to 0.88; P=0.004); not receiving an 'explanation of how long the patient and family could talk' (OR=0.67; 95% CI 0.51 to 0.88; P<0.001); receiving an 'excessive warning of impending death' (OR=1.45; 95% CI 1.03 to 2.03; P=0.033) and having a feeling of 'uncertainty caused by vague explanations about future changes' (OR=1.77; 95% CI 1.38 to 2.27; P<0.001). CONCLUSIONS: Nearly a third of the bereaved families perceived some need to improve the explanation about impending death. To better help patients/families prepare for their end-of-life, clinicians should recognise and explain various impending death signs; find a balance between detailed explanation and excessive warning and address how long they could talk in the remaining time.

Physician Behavior toward Death Pronouncement in Palliative Care Units.

BACKGROUND: There are few studies on bereaved caregivers' perceptions of physician behavior toward death pronouncement. Although previous research indicates that most caregivers are satisfied with physician behavior toward death pronouncement at home hospices, bereaved caregivers' perceptions of death pronouncement in palliative care units (PCUs) have not been investigated. OBJECTIVE: The aim was to examine bereaved caregivers' perceptions of physician behavior toward death pronouncement in PCUs. DESIGN AND METHODS: This was a cross-sectional questionnaire survey of bereaved caregivers who had lost a family member in a PCU. Measures were based on a previous study to assess bereaved caregivers' evaluations of physician behavior toward death pronouncement. RESULTS: Of 861 questionnaires sent to bereaved caregivers, 480 responses were analyzed. Overall, 86% of bereaved caregivers were satisfied with physician behavior toward death pronouncement. Logistic regression analysis revealed three predictors of caregiver satisfaction: "Polite behavior" (odds ratio [OR]: 0.12; 95% confidence intervals [CI]: 0.03-0.46; p < 0.01), "Physician introduced himself/herself to family" (OR: 0.3; 95% CI: 0.1-0.8; p = 0.02), and "Physician confirmed death automatically or routinely" (OR: 11.6; 95% CI: 4.7-28.4; p < 0.01). Caregivers whose family member's death was confirmed by the primarily responsible physician were significantly more satisfied than those whose family member's death was confirmed by an unfamiliar physician. CONCLUSIONS: Most caregivers who lost family members in PCUs were satisfied by the physicians' behavior toward death pronouncement. Politeness was one of the most important factors associated with caregiver satisfaction.

Prevalence and predictors of conflict in the families of patients with advanced cancer: A nationwide survey of bereaved family members.

OBJECTIVES: Family conflict has several adverse impacts on caregivers. Thus, there is significant value in determining the prevalence and predictors of family conflict, which can enable the health care provider to intervene if family conflict arises during end-of-life care. Accordingly, we aimed to explore the prevalence and predictors of conflict among the families of patients with advanced cancer who died in palliative care units. METHODS: This study was a nationwide multicenter questionnaire survey of bereaved family members of cancer patients who died in Japanese palliative care units participating in evaluation of the quality of end-of-life care. RESULTS: We sent out 764 questionnaires, and 529 questionnaires (69.2%) were returned. As 70 family members refused to participate and we could not identify the answers in one questionnaire, we analyzed a total of 458 responses. The average Outcome-Family Conflict score was 13.5 ± 4.9 (maximum score: 39.5), and 42.2% of family members reported at least one family conflict during end-of-life care. Greater family conflict was significantly associated with younger family age, with family members asserting control over decision making for patient care and with communication constraints among family members, although absent family members "coming out of the woodwork" reduced family conflict. CONCLUSIONS: Many families of patients with advanced cancer experienced conflict during end-of-life care. Family members asserting control over decision making and communication constraints among family members after diagnosis of cancer can predict the occurrence of family conflict. Absent family members "coming out of the woodwork" might reduce family conflict in particular cultures.

In vitro photobiochemical characterization of sulfobutylether-ß-cyclodextrin formulation of bufexamac.

The present study aimed to modulate the photoreactivity of bufexamac, with a focus on photostability and phototoxicity, by forming an inclusion complex with sulfobutylether-ß-cyclodextrin (SBECD). The photobiochemical properties of bufexamac were evaluated by reactive oxygen species (ROS) assay and using in vitro photogenotoxic assessment tools. To assess the inclusion properties of SBECD complex with bufexamac, a UV absorption spectroscopic study was also carried out. The influence of SBECD on the photoreactivity of bufexamac was analyzed by ROS assay and photostability test. From the photobiochemical data, superoxide generation from irradiated bufexamac indicated its photoreactivity; however, the photogenotoxic risk of bufexamac was negligible owing to low DNA-binding affinity and DNA-photocleaving activity. SBECD complex of bufexamac was formed, and the association constant of the complex was calculated to be 620M(-1). On the basis of the photochemical data on bufexamac co-existing with SBECD, ROS generation from irradiated bufexamac (200µM) was inhibited by SBECD at concentrations of over 20µM. The degradation constant of bufexamac in SBECD was decreased ca. 30% compared with that of bufexamac, suggesting improvement of its photostability. The phototoxic risk of bufexamac might be attenuated by SBECD complexation, and cyclodextrin inclusion complexes might be a useful approach for modulating the phototoxicity of drugs.

High-throughput screening system for identifying phototoxic potential of drug candidates based on derivatives of reactive oxygen metabolites.

PURPOSE: The present study aimed to develop a high-throughput screening strategy for predicting the phototoxic potential of pharmaceutical substances, using a derivatives-of-reactive-oxygen-metabolites (D-ROM) assay. METHODS: The assay conditions of the D-ROM assay were optimized with a focus on screening run time, sensitivity, solvent system, and reproducibility. The phototoxic potentials of 25 model compounds were assessed by the D-ROM assay, as well as by other screening systems for comparison, including the reactive oxygen species (ROS) assay, the DNA-photocleavage assay, and the 3T3 neutral red uptake phototoxicity test (3T3 NRU PT). RESULTS: Some phototoxic drugs tended to yield D-ROM when exposed to simulated sunlight (250 W/m(2)), whereas D-ROM generation was negligible for non-phototoxic chemicals. Compared with the ROS assay, the assay procedure for the D-ROM assay was highly simplified with a marked reduction in screening run time. Comparative experiments also demonstrated that D-ROM data were related to the outcomes of the DNA-photocleavage assay and the 3T3 NRU PT, with prediction accuracies of 76 and 72%, respectively. CONCLUSION: The D-ROM assay has potential for identifying the phototoxic potential of a large number of new drugs as a 1st screening system in the early stages of drug discovery.

Reactive oxygen species assay-based risk assessment of drug-induced phototoxicity: classification criteria and application to drug candidates.

We have previously demonstrated that the phototoxic potential of chemicals could be partly predicted by the determination of reactive oxygen species (ROS) from photo-irradiated compounds. In this study, ROS assay strategy was applied to 39 marketed drugs and 210 drug candidates in order to establish provisional classification criteria for risk assessment of drug-induced phototoxicity. The photosensitizing properties of 39 model compounds consisting of phototoxic and non-phototoxic chemicals, as well as ca. 210 drug candidates including 11 chemical series were evaluated using ROS assay and the 3T3 neutral red uptake phototoxicity test (NRU PT). With respect to marketed drugs, most phototoxic drugs tended to cause type I and/or II photochemical reactions, resulting in generation of singlet oxygen and superoxide. There seemed to be a clear difference between phototoxic drugs and non-phototoxic compounds in their abilities to induce photochemical reactions. A plot analysis of ROS data on the marked drugs provided classification criteria to discriminate the photosensitizers from non-phototoxic substances. Of all drug candidates tested, 35.2% compounds were identified as phototoxic or likely phototoxic on the basis of the 3T3 NRU PT, and all ROS data for these phototoxic compounds were found to be over the threshold value. Furthermore, 46.3% of non-phototoxic drug candidates were found to be in the subthreshold region. These results verify the usefulness of the ROS assay for understanding the phototoxicity risk of pharmaceutical substances, and the ROS assay can be used for screening purposes in the drug discovery stage.

In vitro phototoxic potential and photochemical properties of imidazopyridine derivative: a novel 5-HT4 partial agonist.

Drug-induced phototoxic skin responses have been recognized as undesirable side effects, and as we previously proposed the determination of reactive oxygen species (ROS) from photo-irradiated compounds can be effective for the prediction of phototoxic potential. In this investigation, we evaluated the photosensitizing properties of imidazopyridine derivative, a novel 5-HT(4) partial agonist, using ROS assay and several analytical/biochemical techniques. Exposure of the compound to simulated sunlight resulted in the significant production of singlet oxygen, which is indicative of its phototoxic potential. In practice, an imidazopyridine derivative under UVA/B light exposure also showed significant photodegradation and even photobiochemical events; peroxidation of fatty acid and genetic damage after DNA-binding, which are considered as causative agents for phototoxic dermatitis. Interestingly, both photodegradation and lipoperoxidation were dramatically attenuated by the addition of radical scavengers, especially singlet oxygen quenchers, suggesting the possible involvement of ROS generation in the phototoxic pathways. In the 3T3 neutral red uptake phototoxicity test, imidazopyridine derivative also showed the phototoxic effect on 3T3 mouse fibroblast cells. These results suggest the phototoxic risk of newly synthesized imidazopyridine derivative and also verify the usefulness of ROS assay for phototoxicity prediction.

In vitro phototoxicity of dihydropyridine derivatives: a photochemical and photobiological study.

Some photosensitizing drugs can cause phototoxic skin responses even after systemic administration; therefore, avoidance of undesired side-effects is a key consideration in drug discovery and development. As a prediction tool for phototoxic risk, we previously proposed the monitoring of reactive oxygen species (ROS) generated from compounds irradiated with UVA/B, which can be effective for understanding photochemical/photobiological properties. In this investigation, we evaluated the photosensitizing properties of a novel dihydropyridine derivative, with bradykinin B(2) receptor antagonist activity (compound A) using our ROS assay and several analytical/biochemical techniques. Exposure of compound A, and several dihydropyridine-type calcium channel antagonists to simulated sunlight resulted in the significant production of singlet oxygen, superoxide, or both, which indicates their photosensitive/phototoxic potential. This is consistent with the observation that compound A under UVA/B light exposure caused significant photodegradation and even peroxidation of fatty acid, which could lead to phototoxic dermatitis. Interestingly, the addition of radical scavengers, especially GSH, MPG and BHA, could attenuate the lipid peroxidation, suggesting the involvement of ROS generation in the phototoxic pathways of compound A. In the 3T3 neutral red uptake phototoxicity test, compound A also showed a phototoxic effect on 3T3 mouse fibroblast cells. These findings also support the usefulness of the ROS assay for the risk assessment studies on the drug-induced phototoxicity even at the early stages of pharmaceutical development.

High-throughput reactive oxygen species (ROS) assay: an enabling technology for screening the phototoxic potential of pharmaceutical substances.

Recently, attention has been drawn to drug-induced phototoxic skin responses, and avoidance of this undesired side effect is necessary for pharmaceutical development. We previously proposed that determination of reactive oxygen species (ROS) generated from photoirradiated compounds would be effective for the prediction of the phototoxic potential. In this investigation, a high-throughput ROS assay system was developed using a multiwell plate and quartz reaction container. The experimental conditions of irradiance uniformity, UV intensity, exposure time, temperature and solvent systems were found to affect the generation of ROS, and thus the conditions of the ROS assay were optimized. The intra- and inter-day R.S.D. values for the determination of ROS from quinine (200 microM) irradiated at 250 W/m(2) for 1h was found to be less than 3.3 and 4.5%, respectively. The results from the ROS assay of 39 compounds allowed us to estimate classification criteria to identify the ability of phototoxic/photochemical responses. The developed assay system will be an effective tool for predicting the phototoxic potential of pharmaceutical candidates in early stage of pharmaceutical development.

Analytical studies on photochemical behavior of phototoxic substances; effect of detergent additives on singlet oxygen generation.

PURPOSE: Monitoring of reactive oxygen species (ROS) generation from photoirradiated compounds would be effective for the prediction of the phototoxic potential. The aim of this investigation was to clarify the possible role of biomimetic vehicle systems on the photochemical properties of phototoxic compounds, focusing on the singlet oxygen generation. MATERIALS AND METHODS: Nine phototoxic and one non-phototoxic compounds (200 microM), dissolved in Tween 20, sodium laurate, or sodium dodecyl sulfate (SDS) micellar solution, were exposed to UVA/B light (250 W/m2), and singlet oxygen generation was monitored by RNO bleaching methodology. Photochemical properties of photosensitizers were also evaluated by UV measurement, and the interaction of photosensitizers with surfactant micelles was assessed by Z-potential and NMR spectroscopic analyses. RESULTS: All phototoxic compounds tended to generate singlet oxygen under light exposure in the all micellar solutions tested. There appeared to be some differences in photoreactivity of both cationic and anionic photosensitizers among the micelles tested, whereas ROS data on anthracene, dissolved in three micellar solutions, were found to be quite similar. Photosensitizers exhibited no significant changes in UV spectral patterns among the dissolving micellar solutions. Addition of cationic photosensitizer at the final concentration of 100 microM into 100 mM SDS solution resulted in the 20 mV increase of zeta potential and transition of NMR spectral pattern, which would reflect the electrostatic interaction with anionic micelles. CONCLUSION: Based on the data obtained, the photoreactivity of photosensitizing molecules, especially cationic and anionic photosensitizers, strongly depends on the physicochemical properties of the microenvironment.