Methodological issues involved in assessing the prevalence of substance abuse in schizophrenia are discussed, and previous research in this area is comprehensively reviewed. Many studies suffer from methodological shortcomings, including the lack of diagnostic rigor, adequate sample sizes, and simultaneous assessment of different types of substance abuse (e.g., stimulants, sedatives). In general, the evidence suggests that the prevalence of substance abuse in schizophrenia is comparable to that in the general population, with the possible exceptions of stimulant and hallucinogen abuse, which may be greater in patients with schizophrenia. Data are presented on the association of substance abuse with demographics, diagnosis, history of illness, and symptoms in 149 recently hospitalized DSM-III-R schizophrenic, schizophreniform, and schizoaffective disorder patients. Demographic characteristics were strong predictors of substance abuse, with gender, age, race, and socioeconomic status being most important. Stimulant abusers tended to have their first hospitalization at an earlier age and were more often diagnosed as having schizophrenia, but did not differ in their symptoms from nonabusers. A history of cannabis abuse was related to fewer symptoms and previous hospitalizations, suggesting that more socially competent patients were prone to cannabis use. The findings show that environmental factors may be important determinants of substance abuse among schizophrenic-spectrum patients and that clinical differences related to abuse vary with different types of drugs.

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BACKGROUND AND PURPOSEHigh plasma levels of fenretinide [N-(4-hydroxyphenyl)retinamide (4-HPR)] were associated with improved outcome in a phase II clinical trial. Low bioavailability of 4-HPR has been limiting its therapeutic applications. This study characterized metabolism of 4-HPR in humans and mice, and to explore the effects of ketoconazole, an inhibitor of CYP3A4, as a modulator to increase 4-HPR plasma levels in mice and to increase the low bioavailability of 4-HPR.EXPERIMENTAL APPROACH4-HPR metabolites were identified by mass spectrometric analysis and levels of 4-HPR and its metabolites [N-(4-methoxyphenyl)retinamide (4-MPR) and 4-oxo-N-(4-hydroxyphenyl)retinamide (4-oxo-4-HPR)] were quantified by high-performance liquid chromatography (HPLC). Kinetic analysis of enzyme activities and the effects of enzyme inhibitors were performed in pooled human and pooled mouse liver microsomes, and in human cytochrome P450 (CYP) 3A4 isoenzyme microsomes. In vivo metabolism of 4-HPR was inhibited in mice.KEY RESULTSSix 4-HPR metabolites were identified in the plasma of patients and mice. 4-HPR was oxidized to 4-oxo-4-HPR, at least in part via human CYP3A4. The CYP3A4 inhibitor ketoconazole significantly reduced 4-oxo-4-HPR formation in both human and mouse liver microsomes. In two strains of mice, co-administration of ketoconazole with 4-HPR in vivo significantly increased 4-HPR plasma concentrations by > twofold over 4-HPR alone and also increased 4-oxo-4-HPR levels.CONCLUSIONS AND IMPLICATIONSMice may serve as an in vivo model of human 4-HPR pharmacokinetics. In vivo data suggest that the co-administration of ketoconazole at normal clinical doses with 4-HPR may increase systemic exposure to 4-HPR in humans.

Synthetic lethality is a molecular-targeted therapy for selective killing of cancer cells. We exploited a lethal interaction between superoxide dismutase 1 inhibition and Bloom syndrome gene product (BLM) defect for the treatment of colorectal cancer (CRC) cells (HCT 116) with a customized lung cancer screen-1-loaded nanocarrier (LCS-1-NC). The drug LCS-1 has poor aqueous solubility. To overcome its limitations, a customized NC, composed of a magnetite core coated with three polymeric shells, namely, aminocellulose (AC), branched poly(amidoamine), and paraben-PEG, was developed for encapsulating LCS-1. Encapsulation efficiency and drug loading were found to be 74% and 8.2%, respectively. LCS-1-NC exhibited sustained release, with ∼85% of drug release in 24 h. Blank NC (0.5 mg/mL) exhibited cytocompatibility toward normal cells, mainly due to the AC layer. LCS-1-NC demonstrated high killing selectivity (104 times) toward BLM-deficient HCT 116 cells over BLM-proficient HCT 116 cells. Due to enhanced efficacy of the drug using NC, the sensitivity difference for BLM-deficient cells increased to 1.7 times in comparison to that with free LCS-1. LCS-1-NC induced persistent DNA damage and apoptosis, which demonstrates that LCS-1-NC effectively and preferentially killed BLM-deficient CRC cells. This is the first report on the development of a potential drug carrier to improve the therapeutic efficacy of LCS-1 for specific killing of CRC cells having BLM defects.

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