Cytochrome P450 2D6 polymorphism in eastern Indian population.

OBJECTIVES: Cytochrome P450 2D6 (CYP2D6) enzyme metabolizes a quarter of prescription drugs. Polymorphisms of CYP2D6 gene and resultant phenotypic variations in metabolic activity have been described in various populations. We assessed the prevalence of CYP2D6 activity phenotypes, employing dextromethorphan (DXM) as probe drug in subjects with at least two parental generations residing in eastern India. MATERIALS AND METHODS: Unrelated healthy subjects took 60 mg DXM after fasting overnight. Blood samples were collected 3 h after dosing and plasma separated. DXM and its primary metabolite dextrorphan (DXT) were measured by liquid chromatography with tandem mass spectrometry. The DXM-to-DXT metabolic ratio (MR) was obtained for each subject. Histogram of MR values suggested bimodal distribution. A polynomial regression equation derived through probit analysis was solved to identify the antimode of the MR values. Subjects with log(MR) < antimode were extensive metabolizers (EMs). Log(MR) ≥ antimode indicated poor metabolizers (PMs). RESULTS: We evaluated the results from 97 participants. The median MR was 0.209 (interquartile range: 0.090-0.609), while the antimode for MR was 3.055. From these, it was inferred that three subjects were PMs, while the rest were EMs. CYP2D6 polymorphism prevalence is low (3.09%; 95% confidence interval: 0.35%-6.54%) in the population of eastern India and matches the prevalence in other zones of the country. CONCLUSIONS: Differences in CYP2D6 activity has treatment implications and may lead to adverse events or therapeutic failure. Phenotyping of subjects receiving CYP2D6 metabolized drugs may help clinicians personalize treatment and avert adverse drug-drug interactions. However, the frequency of the PM phenotype is low in India, and routinely phenotyping for CYP2D6 activity will not be cost-effective. We cannot recommend it at this stage.

CD-340 functionalized doxorubicin-loaded nanoparticle induces apoptosis and reduces tumor volume along with drug-related cardiotoxicity in mice.

BACKGROUND AND OBJECTIVE: Targeted drug delivery of nanoparticles decorated with site-specific recognition ligands is of considerable interest to minimize cytotoxicity of chemotherapeutics in the normal cells. The study was designed to develop CD-340 antibody-conjugated polylactic-co-glycolic acid (PLGA) nanoparticles loaded with a highly water-soluble potent anticancer drug, doxorubicin (DOX), to specifically deliver entrapped DOX to breast cancer cells. METHODS: The study showed how to incorporate water-soluble drug in a hydrophobic PLGA (85:15) based matrix which otherwise shows poor drug loading due to leaching effect. The optimized formulation was covalently conjugated to anti-human epidermal growth factor receptor-2 (HER2) antibody (CD-340). Surface conjugation of the ligand was assessed by flow cytometry, confocal microscopy, and gel electrophoresis. Selectivity and cytotoxicity of the experimental nanoparticles were tested on human breast cancer cells SKBR-3, MCF-7, and MDA-MB-231. Both CD-340-conjugated and unconjugated nanoparticles were undergone in vitro and in vivo characterization. RESULT: Higher level of incorporation of DOX (8.5% W/W), which otherwise shows poor drug loading due to leaching effect of the highly water-soluble drug, was seen in this method. In HER2-overexpressing tumor xenograft model, radiolabeled antibody-conjugated nanoparticles showed preferentially more of the formulation accumulation in the tumor area when compared to the treatments with the unconjugated one or with the other control groups of mice. The ligand conjugated nanoparticles showed considerable potential in reduction of tumor growth and cardiac toxicity of DOX in mice, a prominent side-effect of the drug. CONCLUSION: In conclusion, CD-340-conjugated PLGA nanoparticles containing DOX preferentially delivered encapsulated drug to the breast cancer cells and in breast tumor and reduced the breast tumor cells by apoptosis. Site-specific delivery of the formulation to neoplastic cells did not affect normal cells and showed a drastic reduction of DOX-related cardiotoxicity.

Preferential hepatic uptake of paclitaxel-loaded poly-(d-l-lactide-co-glycolide) nanoparticles - A possibility for hepatic drug targeting: Pharmacokinetics and biodistribution.

Liver cancer is a leading cause of death related to cancer worldwide. Poly(d-l-lactide-co-glycolide) (PLGA) nanoparticles provide prolonged blood residence time and sustained drug release, desirable for cancer treatment. To achieve this, we have developed paclitaxel-loaded PLGA nanoparticles by emulsification solvent evaporation method and evaluated by in vitro and in vivo studies. The results obtained from in vitro study showed that drug loading efficiency was 84.25% with an initial burst release followed by sustained drug release. Cellular uptake and in vitro cytotoxicity of the formulated nanoparticles using HepG2, Huh-7 cancer cells and Chang liver cells were also investigated. The formulated nanoparticles showed more cytotoxic effect at lower concentration and were internalized well by HepG2 cells compared to free-drug and marketed formulation. Prolonged half-life and higher plasma and liver drug concentrations of the formulated nanoparticles were observed as compared to free drug and marketed formulation in rats. Thus, paclitaxel-loaded polymeric nanoparticle has shown its potential for the treatment of liver cancer.

Successful delivery of docetaxel to rat brain using experimentally developed nanoliposome: a treatment strategy for brain tumor.

Docetaxel (DTX) is found to be very effective against glioma cell in vitro. However, in vivo passage of DTX through BBB is extremely difficult due to the physicochemical and pharmacological characteristics of the drug. No existing formulation is successful in this aspect. Hence, in this study, effort was made to send DTX through blood-brain barrier (BBB) to brain to treat diseases such as solid tumor of brain (glioma) by developing DTX-loaded nanoliposomes. Primarily drug-excipients interaction was evaluated by FTIR spectroscopy. The DTX-loaded nanoliposomes (L-DTX) were prepared by lipid layer hydration technique and characterized physicochemically. In vitro cellular uptake in C6 glioma cells was investigated. FTIR data show that the selected drug and excipients were chemically compatible. The unilamellar vesicle size was less than 50 nm with smooth surface. Drug released slowly from L-DTX in vitro in a sustained manner. The pharmacokinetic data shows more extended action of DTX from L-DTX in experimental rats than the free-drug and Taxotere®. DTX from L-DTX enhanced 100% drug concentration in brain as compared with Taxotere® in 4 h. Thus, nanoliposomes as vehicle may be an encouraging strategy to treat glioma with DTX.

Arylamine N-acetyl Transferase (NAT) in the blue secretion of Telescopium telescopium: xenobiotic metabolizing enzyme as a biomarker for detection of environmental pollution.

Telescopium telescopium, a marine mollusc collected from Sundarban mangrove, belongs to the largest mollusca phylum in the world and exudes a blue secretion when stimulated mechanically. The blue secretion was found to metabolize (preferentially) para-amino benzoic acid, a substrate for N-acetyl transferase (NAT), thereby indicating acetyl transferase like activity of the secretion. Attempts were also made to characterise bioactive fraction of the blue secretion and to further use this as a biomarker for monitoring of marine pollution. NAT like enzyme from marine mollusc is a potential candidate for detoxification of different harmful chemicals. A partially purified extract of blue secretion was obtained by fractional precipitation with (NH4)2SO4. From different fractions obtained by precipitation, the 0-30% fraction (30S) displayed NAT like activity (using para amino benzoic acid as a substrate with para nitrophenyl phosphate or acetyl coenzyme A as acetyl group donors). Maximum NAT like enzyme activity was attained at 25°C and at a pH of 6. The enzyme activity was found to be inhibited by 5 mM phenyl methyl sulfonyl fluoride. The divalent metal ions reduced NAT like activity of 30S. Moreover, Cu(2+) and Zn(2+) (at concentration of 1 mM) completely inhibited NAT activity. The thermal stability and bench-top stability studies were performed and it was found that the enzyme was stable at room temperature for more than 24 hours. Results from the present study further indicate that heavy metal content in blue secretion gradually decreased from pre-monsoon to post-monsoon season, which also corresponded to the change in NAT like activity. Therefore, this article stresses the importance of biomarker research for monitoring pollution.