Magister Pharmaceuticae - MPharm / Co-crystals are a solid phase phenomena that could enhance the physicochemical properties of an active pharmaceutical ingredient. A co-crystal has never been incorporated into a liquid dosage form with the assurance of maintaining its co-crystal state until absorption under defined conditions. This study aims to develop a liquid formulation with a nevirapine co-crystal. A protocol was developed to investigate all the five co-formers that were used to make the nevirapine co-crystals to-date. The most appropriate co-former was selected for a liquid dosage form to study the integrity and the scaling up of the co-crystal in a suspension formulation. Co-formers used were viz. saccharin, glutaric acid, salicylic acid, rac-tartaric acid and maleic acid. These were characterized according to their physical, chemical, pharmacological and pharmaceutical properties. A grading scale was used to select the most appropriate co-former for a suspension formulation. Comparatively, saccharin produced the best combination of physical, chemical, pharmacological and pharmaceutical properties, especially with regard to the particle size and the specific gravity which proved to be very useful as optimal criteria for suspension formulation. Upon selection of the ideal co-former, scale-up of the nevirapine saccharin co-crystal was performed from a small scale of 350 mg to a large scale of 5 g. Nevirapine-saccharin (NVSC) co-crystals were prepared utilizing the slow evaporation technique, using methanol as the solvent and the percentage yield of the co-crystals were > 80 %. The identity of co-crystals was confirmed using hot stage microscopy (HSM), differential scanning calorimetry (DSC), fourier transform infra- red (FTIR) and thermogravimetric analysis (TGA). Three co-crystal suspension formulations were prepared using the excipients identified in the branded, Viramune® suspension, with each formulation containing viscosity enhancers such as aerosil 200, carbopol 971G and carbopol 974P. To ascertain the co- crystal integrity in the suspension, it was filtered and the filtrate was identified with DSC and FTIR while the filtered solution was identified with ultraviolet spectroscopy (UV). The co-crystal suspension formulation with optimal pH, viscosity and assurance of co-crystal integrity was the carbopol 974P formulation. The UV and DSC of the filtrate of the suspension revealed that the co-crystal had not separated into its individual components and remained intact while in suspension form irrespective of the excipients added. This formulation proceeded to the quality control stage. It was assessed for its pH, viscosity and dissolution according to the USP 32 standards and compared to the branded nevirapine suspension, Viramune ®, presently on the market. The suspension was characterized for particle size, zeta potential and polydispersity index. The dissolution results assayed by High Performance Liquid Chromatography (HPLC) revealed a drug release of 86 % in the Viramune® suspension while the NVSC co- crystal suspension achieved a drug release of 94% within 30 minutes of dissolution. / National Research Foundation (NRF)

Background: Whether the non-inferior efficacy and safety results of switching virologically suppressed HIV-1-infected patients from nevirapine immediate-release (NVP-IR) to NVP extended-release (NVP-XR) demonstrated in the TRANxITION study conducted in Europe and North America are also applicable to virologically suppressed HIV-infected Taiwanese patients remains unknown. We evaluated the comparative safety and efficacy of continuing NVP-IR versus switching to NVP-XR in virologically suppressed HIV-infected Taiwanese adults receiving combined antiretroviral therapy (cART) regimens. Methods: We conducted a retrospective cohort study at Kaohsiung Veterans General Hospital from April 1, 2013, to March 31, 2015. Eighty-four virologically suppressed HIV-infected adults receiving NVP-IRcART were split into two groups: those continuing with NVP-IR (n = 49) and those being switched to NVP-XR (n = 35). Demographic characteristics, clinical variables, and laboratory findings were compared. Therapeutic drug monitoring of steady-state plasma NVP concentrations and genotype analysis of CYP2B6 516 were also performed in 22 participants. The primary endpoint was continued virological suppression at the end of the study. Secondary endpoints were time to loss of virological response and adverse events. Results: During a mean follow-up of 18.4 months, the NVP-XR group demonstrated similar success at maintaining virological response compared with the NVP-IR group (82.9% vs. 85.7%; P = 0.72). Cox regression analysis indicated that there were no significant differences between NVP regimens for time to loss of virological response (hazard ratio: 0.940; P = 0.754). Furthermore, there were no significant differences in adverse events between these two groups. In the 22 participants, there was a non-significantly lower level of steady-state plasma NVP concentrations in the NVP-XR group than in NVP-IR recipients (5145.0 ng/mL vs. 6775.0 ng/mL; P = 0.267). The prevalence of CYP2B6 516 GT was 86.6%, and there was no significant difference in the distribution of CYP2B6 516 between these two groups. Conclusions: We found that switching from NVP-IR to NVP-XR appeared to have similar safety and efficacy compared with continuing NVP-IR among virologically suppressed, HIV-infected Taiwanese patients. Our finding of higher C-trough levels in both groups compared with other studies conducted in Caucasian populations and the high prevalence of CYP2B6 516 GT requires further investigation in a larger Taiwanese cohort.

Submitted in partial fulfilment of the requirements for the degree of Master of Public Health, in the field of Maternal and Child Health, to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, September 2014 / Introduction: Nevirapine (NVP) is used in combination antiretroviral treatment especially for pregnant HIV infected women. NVP has been shown to be inferior and more toxic than other similar drugs, but continues to be used in developing countries due to cost. Aim: This study aimed to determine the prevalence of NVP toxicity and associated factors among 478 pregnant women from three public health facilities in inner city Johannesburg. Materials and methods: We employed a cross-sectional retrospective record review study design to analyse the records of 478 pregnant women in the above mentioned public health facilities. Variables including demographic (age, weight, gestational age) and clinical (CD4 cell count, WHO HIV clinical stage, prior ART experience) characteristics were extracted and the association between these characteristics and the development of toxicity post NVP exposure was explored. Results: The study found that approximately nine out of ten women (89.5%) were ART naïve at the time of NVP initiation. When compared with ART naïve women, ART experienced women had a slightly higher mean CD4 cell count, however, for both groups of women, mean CD4 cell count was less than 250 cells/mm3. Overall, 85.1% of women had a CD4 cell count less than 250 cells/mm3. More than half (55.3%) of the women were in the third trimester of pregnancy and the majority (82%) classified as WHO HIV clinical stage one. At least one adverse event was reported in 63 (13.2%) women. Mild skin rash was the most prevalent adverse event, occurring in 9.6% of women. Hepatotoxicity occurred in 5.3% of women and severe skin rash occurred in 1.5% of women. Almost 85% of adverse events occurred in women with CD4 cell counts <250 cells/mm3. WHO HIV clinical stage II and IV were significantly associated with the overall development of toxicity (ρ <0.01). Conclusions: Whilst the overall prevalence of mild and severe skin rash in this sample was less than that demonstrated in earlier studies, a higher overall prevalence of hepatotoxicity was found. When compared with ART naïve women, ART experienced women were found to have a higher prevalence of mild skin rash. Hepatotoxicity and severe skin rash only occurred in ART naïve women. In this sample, CD4 cell count ≥250 cells/mm3 was not associated with the development of NVP adverse events. Recommendations: Our findings support the continued use of NVP as part of combination ART regimens in women of African descent. In contrast with previously published data, our study showed a significant association between WHO HIV clinical stage and NVP toxicity, our study also included relatively few women with higher CD4 cell counts. Further research including predominantly healthy HIV infected pregnant African women as well as women with higher CD4 cell counts is required in order to fully explore the association between these variables and the development of NVP post-exposure toxicity.

Nevirapine (NVP) can cause serious idiosyncratic drug reactions (IDRs); specifically, skin rash and hepatotoxicity. Treatment of rats or mice with NVP led to covalent binding to hepatic proteins. Studies of this covalent binding including the use of a deuterated analog of NVP leading to a decrease in oxidation of the methyl group indicated that the metabolite responsible for covalent binding in the liver is a quinone methide. Covalent binding in NVP-treated rats was also observed in the epidermis but by a different pathway. Incubation of 12-OH-NVP sulfate with homogenized human and rat skin led to extensive covalent binding. Inhibition of sulfation in the liver significantly decreased 12-OH-NVP sulfate in the blood, but it did not prevent covalent binding in the skin or the rash. In contrast, topical application of a sulfotransferase inhibitor prevented covalent binding in the skin as well as the rash, but only where it was applied. In contrast to rats, treatment of mice with NVP did not result in covalent binding in the skin or skin rash. These findings provide compelling evidence that 12-OH-NVP sulfate formed in the skin is responsible for the skin rash. IL-1β and IL-18 production in the skin of rats treated with NVP were increased. An anti-IL-1ß antibody significantly decreased rash severity. These cytokines were also produced by incubation of human keratinocytes with 12-OH-NVP sulfate. These data indicate that 12-OH-NVP sulfate activates the NLRP3 inflammasome, a pathway known to be responsible for contact hypersensitivity rashes. In summary, NVP was found to produce two different reactive metabolites, a quinone methide species in the liver, and a benzylic sulfate in the skin. Significant liver injury did not occur, presumably due to immune tolerance. Although it is usually assumed that reactive metabolites are responsible for most IDRs, this is the first example to actually demonstrate that a specific reactive metabolite is responsible for an IDR. This is also the first study to show that sulfotransferase in the skin is responsible for bioactivation of a drug leading to a skin rash. It is likely that there are other drugs that cause skin rashes by a similar mechanism.

Nevirapine (NVP) can cause serious idiosyncratic drug reactions (IDRs); specifically, skin rash and hepatotoxicity. Treatment of rats or mice with NVP led to covalent binding to hepatic proteins. Studies of this covalent binding including the use of a deuterated analog of NVP leading to a decrease in oxidation of the methyl group indicated that the metabolite responsible for covalent binding in the liver is a quinone methide. Covalent binding in NVP-treated rats was also observed in the epidermis but by a different pathway. Incubation of 12-OH-NVP sulfate with homogenized human and rat skin led to extensive covalent binding. Inhibition of sulfation in the liver significantly decreased 12-OH-NVP sulfate in the blood, but it did not prevent covalent binding in the skin or the rash. In contrast, topical application of a sulfotransferase inhibitor prevented covalent binding in the skin as well as the rash, but only where it was applied. In contrast to rats, treatment of mice with NVP did not result in covalent binding in the skin or skin rash. These findings provide compelling evidence that 12-OH-NVP sulfate formed in the skin is responsible for the skin rash. IL-1β and IL-18 production in the skin of rats treated with NVP were increased. An anti-IL-1ß antibody significantly decreased rash severity. These cytokines were also produced by incubation of human keratinocytes with 12-OH-NVP sulfate. These data indicate that 12-OH-NVP sulfate activates the NLRP3 inflammasome, a pathway known to be responsible for contact hypersensitivity rashes. In summary, NVP was found to produce two different reactive metabolites, a quinone methide species in the liver, and a benzylic sulfate in the skin. Significant liver injury did not occur, presumably due to immune tolerance. Although it is usually assumed that reactive metabolites are responsible for most IDRs, this is the first example to actually demonstrate that a specific reactive metabolite is responsible for an IDR. This is also the first study to show that sulfotransferase in the skin is responsible for bioactivation of a drug leading to a skin rash. It is likely that there are other drugs that cause skin rashes by a similar mechanism.

Magister Public Health - MPH / Objective: The study aim was to measure the operational effectiveness of a single dose Nevirapine for PMTCT programme among infants aged six weeks in Khomas region of Namibia.Methods: This was a retrospective record review quantitative study based on a descriptive approach. The record review aimed at measuring operational effectiveness through the distribution of certain variables among HIV exposed infants including the socio economic variables such as age, sex and the breast feeding practices of their mothers. A total of 451 HIV positive mothers and their infant pairs` record registers were reviewed in two hospitals of Khomas region, Namibia.Results: A total of 451 PMTCT mothers’ records for the year 2007 (median age 29 years) were reviewed in the Katutura and Windhoek Central hospitals of Namibia.. The HIV prevalence among infants aged six weeks or more out of the total 167 tested was 5% (95%CI, 0.9 -3.7). Conclusion: The findings from this study shows that although the rate of PMTCT in tested infants was low, registers for maternity and infant follow up are extremely poorly completed with the vast amounts of missing information making it difficult to assess programme effectiveness and monitor programme outcomes. PMTCT programme registers and routine monitoring and evaluation data need to be strengthened.

An animal model of nevirapine (NVP)-induced skin rash was used to test the hypothesis that sulfonation of 12-OH NVP, a metabolite of NVP proven essential for rash development, is the link between 12-OH NVP and the skin rash. Female Brown Norway (BN) rats were co-treated with NVP or 12-OH NVP and sulfation inhibitors dehydroepiandrosterone (DHEA) and salicylamide. Co-treatment with salicylamide markedly decreased formation of the sulfate conjugate but did not prevent development of the rash suggesting that the sulfate is not involved. However, it is not known whether the sulfate formation in the skin was affected. Co-treatments with DHEA decreased the sulfate formation and prevented the rash but also had other effects on NVP metabolism. This implies that the sulfate metabolite is responsible for the rash. Additional studies will be required to resolve these conflicting results.

An animal model of nevirapine (NVP)-induced skin rash was used to test the hypothesis that sulfonation of 12-OH NVP, a metabolite of NVP proven essential for rash development, is the link between 12-OH NVP and the skin rash. Female Brown Norway (BN) rats were co-treated with NVP or 12-OH NVP and sulfation inhibitors dehydroepiandrosterone (DHEA) and salicylamide. Co-treatment with salicylamide markedly decreased formation of the sulfate conjugate but did not prevent development of the rash suggesting that the sulfate is not involved. However, it is not known whether the sulfate formation in the skin was affected. Co-treatments with DHEA decreased the sulfate formation and prevented the rash but also had other effects on NVP metabolism. This implies that the sulfate metabolite is responsible for the rash. Additional studies will be required to resolve these conflicting results.

Background: Antiretroviral therapy (ART), notably lopinavir and nevirapine substantially reduces Human immune-deficiency virus (HIV) associated morbidity and mortality in HIVinfected children. Low concentrations of nevirapine and lopinavir have been linked to inferior virological outcomes; it is recommended that lopinavir and nevirapine concentrations are maintained above 1 mg/L and 3 mg/L, respectively, in order to maintain viral suppression. Adherence to both lopinavir and nevirapine ART, respectively has long known to be a crucial contributor to HIV treatment success. Lopinavir and nevirapine pharmacokinetics demonstrate considerable inter-individual variability, which may affect treatment outcomes. At least part of this variability may be explained by host genetic factors. Associations between human genetic variants and exposure to lopinavir and nevirapine are incompletely understood, and have not been studied in a South African paediatric population. Data in this thesis were from a clinical trial conducted at Rahima Moosa Mother and Child Hospital in Johannesburg to assess whether NVP can be re-used (Post-randomization Phase) among 323 children exposed to NVP for PMTCT if they are first suppressed on ritonavir-boosted lopinavir based regimen (Pre-randomization Phase). This thesis assessed the relationship between serial clinic visits lopinavir (Pre-and-Post-randomization) and nevirapine (Postrandomization) concentrations and/or percentage adherence(Pre-and-Post-randomization) and virological outcomes in children. Moreover, population pharmacokinetics models were used to characterise lopinavir and nevirapine parameters. From the final models parameters were derived and were used to assess the relationship between lopinavir and nevirapine pharmacokinetics and genetic polymorphism relevant to both drugs Methods: Cox proportional hazard regression modelling for multiple failure events was used to estimate the crude and adjusted hazard effect of lopinavir (Pre-and Post-randomization) and nevirapine(Post-randomization) concentrations and/or percent adherence(Pre-and Post-randomization) of viral load>400 copies/mL (Pre-randomization) and >50 copies/mL (Post-randomization), respectively. The population means and variances of lopinavir and nevirapine pharmacokinetic parameters at steady state were estimated using non-linear mixed-effects regression. The final models of lopinavir and nevirapine were used to derive individual clearances (CL/F), minimum concentrations (Cmin) and area under the concentration time curves (AUC). The associations between model-derived pharmacokinetic parameters and genotypes in selected genes relevant to lopinavir or nevirapine were explored. Results: In 237 children pre-randomization with viral loads and lopinavir concentrations, the crude and adjusted Cox models revealed significant associations between virologic failure (viral load>400 copies/mL) and both lopinavir plasma concentrations (<1/mg/L) and pretreatment height-for-age z-scores but not percent adherence. In 99 children postrandomization, lopinavir concentrations >1 mg/L reduced the risk of viremia (viral load >50 copies/mL) with about 40%, compared to children with LPV <1 mg/L. No association was found with percent adherence in this group. In 95 children on nevirapine post-randomization, nevirapine concentrations were not significantly associated with increased hazard of viremia (viral load >50 copies/mL). Similarly, there was no significant association with percent adherence in this group. Lopinavir and nevirapine pharmacokinetics were both separately best described with a one compartment models with absorption lag time and transit compartment absorption models, respectively. There was an age driven effect on lopinavir and nevirapine relative bioavailability, respectively. After adjusting for multiple testing, there was no significant association between lopinavir CL/F, Cmin and AUC and genetic polymorphisms in the ABCB1, CYP3A4, CYP3A5 and SLCO1B1. CYP2B6 516G→T and CYP2B6 983T→C were associated with NVP CL/F. CYP2B6 983T→C was associated with NVP Cmin and AUC. Additionally, polymorphisms in the ABCB1 and CYP3A5 were independently associated with NVP CL/F, Cmin and AUC. Conclusions: Lopinavir concentrations <1mg/L were associated with the increased hazard of viremia (viral load >400 copies/mL or >50 copies/mL). The results suggest that lopinavir plasma concentration monitoring at a routine clinic visit may be a useful tool in identifying sub-therapeutic antiretroviral concentrations in children, and this could be used as a guide to therapeutic drug monitoring in children. There was no statistically significant association between polymorphisms in the ABCB1, CYP3A4, CYP3A5 and SLCO1B1 and lopinavir pharmacokinetics. Polymorphisms in the ABCB1, CYP2B6 CYP3A4 and CYP3A5 predicted nevirapine pharmacokinetics.

Thesis (DTech (Chemistry))--Cape Peninsula University of Technology, 2016. / Bimetallic silver-platinum (Ag-Pt) nanoparticles (NPs) were synthesized via simultaneous reduction of varying mole fractions of metal precursors H2PtCl6.6H2O and AgNO3 by sodium citrate. Kinetics rates of were as follows; Ag NPs (0.079 s-1), Ag-Pt NPs 1:1 (0.082 s-1) and Pt NPs (0.006 s-1). The UV visible spectrum of Ag NPs exhibited a characteristic absorption band while Pt NPs and Ag-Pt bimetallic NPs exhibited no absorption peaks. Successful formation of both monometallic and bimetallic NPs was confirmed via transmission electron microscopy (TEM); selected area electron diffraction (SAED) and energy dispersive X-ray (EDX) analysis. TEM images depicted core-shell arrangement in the bimetallic (BM) NP ratios (1:1, 1:3 and 3:1) with an average particle size of 21 nm. The particle size trend where monometallic Ag NPs (60 nm) > Pt NPs (2.5 nm) while in the BM ratios Ag-Pt NPs 1:1 (25 nm) > Ag-Pt NPs 1:3 (20.7 nm). X-ray diffraction (XRD) patterns depicted crystallinity in all the synthesized NPs with confirmation of the face centred cubic structure formation. Transducers were fabricated by drop casting the nanoparticless on the glassy carbon electrode (GCE) and their electrochemical properties studied via cyclic voltammetry (CV). High diffusion coefficient (D) and surface coverage reported were Ag NPs (6.70 cm2 s-1, 54.49 mol cm-2 ) and Ag-Pt NPs 1:1 (0.62 cm2 s-11.85 mol cm-2). Electrochemical band gaps ranged from 1.45 to 1.70 eV while the Tauc’s model band gaps of nanoparticles were found in the range of 2.48 to 3.84 eV. These band gaps were found to be inversely proportional to particle size, which was attributed to the quantum confinement effect. Both optical and electrochemical band gap portrayed similar trend as well as an increase in the BM NP relative to monometallics. These nanoparticles band gaps are within semiconductor range for most materials. The electrochemical behaviour and surface characteristics were studied using 0.1 M PBS solution by scan rates variations for the diffusion coefficient determination of modified electrodes which ranged from 0.62 to 6.10 x 10-5 cm2 s-1. Laviron’s approach for parameters such as apparent charge transfer rate constant, ks, and charge transfer coefficient, α, for electron transfer between NPs and GCE were investigated using CV. The values of electron-transfer coefficients ranged from 0.1 to 0.7 while the charge transfer rate constant values ranged from 0.74 to 31.13 s-1.