The mosquito Anopheles gambiae is the principal vector for malaria in sub-Saharan Africa. The ability of A. gambiae to transmit malaria is strictly related to blood feeding and digestion, which releases nutrients for oogenesis, as well as substantial amounts of highly toxic free heme. Heme degradation by heme oxygenase (HO) is a common protective mechanism, and a gene for HO exists in the An. gambiae genome HO (AgHO), although it has yet to be functionally examined. Here, we have cloned and expressed An. gambiae HO (AgHO) in E. coli. Purified recombinant AgHO bound hemin stoichiometrically to form a hemin-enzyme complex similar to other HOs, with a K of 3.9 ± 0.6 μM; comparable to mammalian and bacterial HOs, but 7-fold lower than that of Drosophila melanogaster HO. AgHO also degraded hemin to biliverdin and released CO and iron in the presence of NADPH cytochrome P450 oxidoreductase (CPR). Optimal AgHO activity was observed at 27.5 °C and pH 7.5. To investigate effects of AgHO inhibition, adult female A. gambiae were fed heme analogues Sn- and Zn-protoporphyrins (SnPP and ZnPP), known to inhibit HO. These led to a dose dependent decrease in oviposition. Cu-protoporphyrin (CuPP), which does not inhibit HO had no effect. These results demonstrate that AgHO is a catalytically active HO and that it may play a key role in egg production in mosquitoes. It also presents a potential target for the development of compounds aimed at sterilising mosquitoes for vector control.

Funding information Janssen PharmaceuticalsMedicines for Malaria VentureAims: Given the increasing emergence of drug resistance in Plasmodium, new antimalarials are urgently required. P218 is an aminopyridine that inhibits dihydrofolate reductase being developed as a malaria chemoprotective drug.Assessing the effect of new compounds on cardiac intervals is key during early drug development to determine their cardiac safety.Methods: This double-blind, randomized, placebo-controlled, parallel group study evaluated the effect of P218 on electrocardiographic parameters following oral administration of seven single-ascending doses up to 1000 mg in 56 healthy volunteers. Participants were randomized to treatment or placebo at a 3:1 ratio. P218 was administered in the fasted state with standardized lunch served 4 hours after dosing.12-lead ECGs were recorded in triplicate at regular intervals on the test day, and at 48, 72, 120, 168, 192 and 240 hours thereafter. Blood samples for pharmacokinetic evaluations were collected at similar time points. Concentration-effect modelling was used to assess the effect of P218 and its metabolites on cardiac intervals.Results: Concentration-effect analysis showed that P218 does not prolong the QTcF, J-Tpeak or TpTe interval at all doses tested. No significant changes in QRS or PR intervals were observed. Two-sided 90% confidence intervals of subinterval effects of P218 and its metabolites were consistently below the regulatory concern threshold for all doses. Study sensitivity was confirmed by significant shortening of QTcF after a meal. Conclusion:Oral administration of P218 up to 1000 mg does not prolong QTcF and does not significantly change QRS or PR intervals, suggesting low risk for druginduced proarrhythmia.

Cortexolone 17α-propionate, also known as clascoterone, is a potent androgen receptor inhibitor intended for the topical treatment of skin diseases associated with androgenic pathway alterations. In nonclinical studies, cortexolone 17α-propionate was found to have a weak inhibitory effect on human Ether-à-go-go-Related Gene (hERG) potassium channels, which are vital for normal electrical activity in the heart. When used in a cream formulation, little cortexolone 17α-propionate is absorbed. However, the solution formulation developed for the treatment of androgenetic alopecia leads to a measurable systemic concentration and accumulation of the antiandrogen. This phase 1 study assessed the effect of cortexolone 17α-propionate on the QTc interval using concentration-effect analysis and the effect of a meal on QTc to confirm assay sensitivity. Thirty-two volunteers were randomly assigned to receive the active drug or a matching vehicle as placebo. Participants were dosed twice daily on days 1 to 3 (225 mg applied topically as a 7.5% solution 12 hours apart) and once on day 4. Pharmacokinetic and electrocardiogram assessments were performed after supratherapeutic doses. Assay sensitivity was successfully confirmed by using the food effect on the QTc interval. The results of this concentration-QTc analysis demonstrate that cortexolone 17α-propionate and its metabolite/degradation product had no effect on the QTc interval in the concentration range tested.

Nolasiban is an orally active oxytocin receptor antagonist being developed to increase the efficiency of assisted reproductive technologies. This study evaluated the pharmacokinetics, pharmacodynamics, and cardiac safety of nolasiban in 45 healthy women of child-bearing age. Nolasiban was administered in a fasted state with a standardised lunch served 4.5 h post-dose. Concentration-effect modelling was used to assess the effect of two dosages of nolasiban (900 mg and 1800 mg) on QTc following single-dose administration. We found no significant change in QTc at all tested dosages. Two-sided 90% confidence intervals of geometric mean Cmax for estimated QTc effects of nolasiban were below the threshold of regulatory concern. The sensitivity of the assay to detect small changes in QTc was confirmed by a significant shortening of QTc between 2 and 4 h after consumption of a meal, which served to validate the model. Independent of the nolasiban assessment, this study also explored the effects of sex hormones on ECG parameters, especially QT subintervals. We found a significant relationship between JTpc and oestradiol. Heart rate was negatively correlated with progesterone. This study confirms the cardiovascular safety of nolasiban and describes relationships of sex hormones and ECG parameters.

To estimate the effectiveness of vaccines in development, a robust mechanism is required to understand immunity, risks of reinfection and measure the immune response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and how this may change over time. This study is a longitudinal analysis of COVID-19 infection rates using PCR, membrane immunoassay and chemiluminescent microparticle immunoassay (CMIA) diagnostic tests. Our data confirm that antibody levels wane in the three months after symptom onset. Comparison of the three methods used suggests that quantitative CMIA testing may exaggerate numbers of COVID-19 negative individuals.

Two open-label, single-dose, randomized crossover studies were conducted in healthy Japanesemen to (1) assess dose proportionality of 5 doses (1.38, 2.75, 5.5, 8.25, and 11.0 mg) of Lafenta, a novel matrix-type transdermal fentanyl patch with a rate-controlling membrane; and (2) compare patch bioequivalence (11.0 mg) with a commercially available reference patch (Durotep MT Patch [16.8 mg]). Pharmacokinetics, adhesion performance, residual fentanyl, and safety parameters were assessed. Increases in mean AUC 0-t and C max after application of the test patch were dose proportional. The test patch (11.0 mg) was bioequivalent to the 16.8-mg reference patch in terms of mean AUC 0-inf , AUC 0-t , and C max. Residual fentanyl levels 72 hours postapplication were lower in the test than in the reference patch. Differences in adhesion performance between the test and the reference patch did not affect delivery efficacy and reliability of the novel matrix patch. Safety findings were in line with previous experiences with fentanyl. Both studies showed low variation in fentanyl exposure and delivery via the test patch. The test patch provided equivalent fentanyl exposure at a lower dose than the reference patch formulation with lower variability and the potential to lower medicinal waste.

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