The pharmacokinetic interaction between ivacaftor and ritonavir in healthy volunteers.

AIMS: The aim of this study was to determine the pharmacokinetic interaction between ivacaftor and ritonavir. METHODS: A liquid chromatography mass spectrometry (LC-MS) method was developed for the measurement of ivacaftor in plasma. An open-label, sequential, cross-over study was conducted with 12 healthy volunteers. Three pharmacokinetic profiles were assessed for each volunteer: ivacaftor 150 mg alone (study A), ivacaftor 150 mg plus ritonavir 50 mg daily (study B), and ivacaftor 150 mg plus ritonavir 50 mg daily after two weeks of ritonavir 50 mg daily (study C). RESULTS: Addition of ritonavir 50 mg daily to ivacaftor 150 mg resulted in significant inhibition of the metabolism of ivacaftor. Area under the plasma concentration-time curve from time 0 to infinity (AUC0-inf obv ) increased significantly in both studies B and C compared to study A (GMR [95% CI] 19.71 [13.18-31.33] and 19.77 [14.0-27.93] respectively). Elimination half-life (t1/2 ) was significantly longer in both studies B and C compared to study A (GMR [95% CI] 11.14 [8.72-13.62] and 9.72 [6.68-12.85] respectively). There was no significant difference in any of the pharmacokinetic parameters between study B and study C. CONCLUSION: Ritonavir resulted in significant inhibition of the metabolism of ivacaftor. These data suggest that ritonavir may be used to inhibit the metabolism of ivacaftor in patients with cystic fibrosis (CF). Such an approach may increase the effectiveness of ivacaftor in 'poor responders' by maintaining higher plasma concentrations. It also has the potential to significantly reduce the cost of ivacaftor therapy.

Identification of (2-aminopropyl)indole positional isomers in forensic samples.

In 2012, 5-(2-aminopropyl)indole (5-API, 5-IT) was reported by Norwegian authorities to the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) via the Early Warning System (EWS). The 3- isomer, 3-(2-aminopropyl)indole (3-API, AMT, alpha-methyltryptamine), has been available on the recreational drugs market for a somewhat longer time, having first been reported to the EMCDDA by Finnish authorities in 2001. Both isomers are available from online vendors of 'legal highs'. Recently, three forensic drug cases (two tablets and one powder) were presented for routine analysis and the active constituent was tentatively identified as an API isomer. The six positional isomers (2-, 3-, 4-, 5-, 6- and 7-(2-aminopropyl)indoles) were synthesized and analyses by a combination gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-mass spectrometry (LC-MS) showed that these could be readily discriminated thus facilitating the identification of 3-API in the tablets and 5-API in the powder. With exception of 5- and 6-APIs, which co-eluted, it was found possible to separate the isomers by GC without derivatization. LC separation also proved to be a feasible method for the discrimination of the isomers. Although the 2- and 7- isomers were not fully resolved by LC, it was found possible to distinguish them using their product ion spectra as the 2- isomer produced the m/z 132 fragment ion formed by loss of vinylamine, whereas the 7- isomer formed m/z 158 through loss of methylamine. In the synthesis 2-API, a novel tricyclic by-product was formed in an annulation reaction where the reaction solvent, tetrahydrofuran, was incorporated into the molecule.

An unusual presentation of a customs importation seizure containing amphetamine, possibly synthesized by the APAAN-P2P-Leuckart route.

During the analysis of an Irish customs seizure (14 packages each containing approximately one kilogram of a white wet paste) were analysed for the suspected presence of controlled drugs. The samples were found to contain amphetamine and also characteristic by-products including benzyl cyanide, phenylacetone (P2P), methyl-phenyl-pyrimidines, N-formylamphetamine, naphthalene derivatives and amphetamine dimers. The analytical results corresponded with the impurity profile observed and recently reported for the synthesis of 4-methylamphetamine from 4-methylphenylacetoacetonitrile [1]. The synthesis of amphetamine from alpha-phenylacetoacetonitrile (APAAN) was performed (via an acid hydrolysis and subsequent Leuckart reaction) and the impurity profile of the product obtained was compared to those observed in the customs seizure. Observations are made regarding the route specificity of these by-products.

The cost-effectiveness of cotrimoxazole prophylaxis in HIV-infected children in Zambia.

OBJECTIVE: To assess the cost-effectiveness of cotrimoxazole prophylaxis in HIV-infected children in Zambia, as implementation at the local health centre level has yet to be undertaken in many resource-limited countries despite recommendations in recent updated World Health Organization (WHO) guidelines. DESIGN: A probabilistic decision analytical model of HIV/AIDS progression in children based on the CD4 cell percentage (CD4%) was populated with data from the placebo-controlled Children with HIV Antibiotic Prophylaxis trial that had reported a 43% reduction in mortality with cotrimoxazole prophylaxis in HIV-infected children aged 1-14 years. METHODS: Unit costs (US$ in 2006) were measured at University Teaching Hospital, Lusaka. Cost-effectiveness expressed as cost per life-year saved, cost per quality adjusted life-year (QALY) saved, cost per disability adjusted life-year (DALY) averted was calculated across a number of different scenarios at tertiary and primary healthcare centres. RESULTS: : Cotrimoxazole prophylaxis was associated with incremental cost-effectiveness ratios (ICERs) of US$72 per life-year saved, US$94 per QALY saved and US$53 per DALY averted, i.e. substantially less than a cost-effectiveness threshold of US$1019 per outcome (gross domestic product per capita, Zambia 2006). ICERs of US$5 or less per outcome demonstrate that cotrimoxazole prophylaxis is even more cost-effective at the local healthcare level. The intervention remained cost-effective in all sensitivity analyses including routine haematological and CD4% monitoring, varying starting age, AIDS status, cotrimoxazole formulation, efficacy duration and discount rates. CONCLUSION: Cotrimoxazole prophylaxis in HIV-infected children is an inexpensive low technology intervention that is highly cost-effective in Zambia, strongly supporting the adoption of WHO guidelines into essential healthcare packages in low-income countries.