Acetylcholine (ACh) is a neurotransmitter/neuromodulator in the nematode nervous system and induces its effects through interaction with both ligand-gated ion channels (LGICs) and G proteincoupled receptors (GPCRs). The structure, pharmacology and physiological importance of LGICs have been appreciably elucidated in model nematodes, including parasitic species where they are targets for anthelmintic drugs. Significantly less, however, is understood about nematode ACh GPCRs, termed GARs (G protein-linked ACh receptors). What is known comes from the free-living Caenorhabditis elegans as no GARs have been characterized from parasitic species. Here we clone a putative GAR from the pig gastrointestinal nematode Ascaris suum with high structural homology to the C. elegans receptor GAR-1. Our GPCR, dubbed AsGAR-1, isalternatively spliced and expressed in the head and tail of adult worms but not in dorsal or ventralbody wall muscle, or the ovijector. ACh activated AsGAR-1 in a concentration-dependent manner but the receptor was not activated by other small neurotransmitters. The classical muscarinic agonists carbachol, arecoline, oxotremorine M and bethanechol were also AsGAR-1 agonists but pilocarpine was ineffective. AsGAR-1 activation by ACh was partially antagonized by the muscarinic blocker atropine but pirenzepine and scopolamine were largely ineffective. Certain biogenic amine GPCR antagonists were also found to block AsGAR-1. Our conclusion is that Ascaris possesses G protein-coupled ACh receptors that are homologous in structure to thosepresent in C. elegans, and that although they have some sequence homology to vertebrate muscarinic receptors, their pharmacology is atypically muscarinic.

BackgroundRapidly disintegrating or ‘fast-melt’ oral formulations have been developed recently to facilitate drug intake among patients. Even though these formulations have helped to improve therapy adherence, some of their limitations include: the dissolution time, their facility to be swallowed, and the dosage strengths that may be accommodated. To overcome these limitations, a novel, porous, quickly disintegrating, and easier-to-swallow fast-melt formulation based on powder-liquid, three-dimensional printing (3DP) technology has been developed.ObjectiveTo determine and compare the relative bioavailability of a novel 3DP fast melt containing levetiracetam in healthy male and female subjects.MethodsThis study included 33 subjects in a three-way crossover design. The 3DP fast-melt formulation was compared against the conventional immediate-release tablet of levetiracetam (Keppra®) after a single 1000-mg dose administration under fasting conditions following the bioequivalence criteria used by the US Food and Drug Administration. This study also evaluated the food effect on the bioavailability of the levetiracetam 3DP fast melt. A small sip of liquid was used to administer the fast-melt formulation.ResultsThe novel 3DP fast melt showed rapid oral disintegration (mean duration of 11 s from a sip of water to completion of swallowing) following its administration, and did not affect the pharmacokinetic profile of levetiracetam. A lower absorption peak was observed after administration of the 3DP fast melt under fed conditions, as expected. In addition, time of maximum measured plasma concentration was delayed by approximately 3.5 h under fed conditions. These effects are unlikely to be of clinical significance with long-term administration, and may help reduce the adverse events and facilitate compliance. Finally, no change in the oral mucosa was observed with the 3DP fast melt while being as safe and well tolerated as the standard levetiracetam tablet.ConclusionThis study quantified the rapid disintegration of the 3DP levetiracetam fast melt and confirmed its equivalent rate and extent of absorption to the conventional immediate-release tablet in the fasted state, using standard bioequivalence criteria.

<b><i>Background:</i></b> Natural history (NH) studies, using observational methods, are common in rare and orphan diseases (80% of which have a genetic component). There is profound interest in identifying genetic mutations driving these diseases in these studies to support the formulation of targeted precision medicines. The global regulatory classification of NH studies with novel molecular biomarker collection has not been clearly delineated, presenting researchers with the challenge of determining how these studies are classified and regulated across multiple geographies. <b><i>Objective:</i></b> The aim of this investigation was to conduct a review of regulations related to NH studies and genetic testing to elucidate regulatory pathways to inform clinical researchers in the field. <b><i>Methods:</i></b> Regulatory provisions for NH studies and genetic testing were obtained from Pharmaceutical Product Development (PPD)’s propriety regulatory intelligence database and by surveying the company’s country-specific regulatory experts. A literature search was conducted in the Google Scholar search engine and PubMed for supplementary information. <b><i>Results:</i></b> Nineteen countries were evaluated; 37% classified NH studies with biomarker collection as noninterventional and 26% required regulatory approval (increasing to 47% when molecular biomarker testing was introduced). No regulatory provisions for genetic testing could be identified in 32% of countries, and 58% did not have binding requirements for genetic counseling. <b><i>Conclusion:</i></b> Lack of harmonization of regulations governing NH studies with molecular biomarker collection contributes to the operational complexity of conducting multinational studies in orphan and rare diseases. A set of harmonized international guidelines for these studies would improve efficiency, and this may be on the horizon with the recent adaption of International Conference on Harmonisation (ICH) guideline E18.