Dexpramipexole (KNS-760704), the R(+) enantiomer of pramipexole, is under development by Knopp Neurosciences and Biogen Idec as a potential neuroprotective therapy for amyotrophic lateral sclerosis (ALS), a universally fatal neurodegenerative disease. Pramipexole, exclusively the S(-) enantiomer, is a non-ergot dopaminergic autoreceptor agonist that is currently marketed for use in the treatment of Parkinson's disease and restless legs syndrome. Pramipexole has been proposed to exert a broad spectrum of neuroprotective properties, primarily through antioxidant effects, inhibiting apoptotic enzymes and preserving mitochondrial structure and activity. More recent work has suggested that pramipexole possesses anti-excitotoxic properties, raising the possibility of beneficial effects in patients with ALS. However, pramipexole has high intrinsic dopaminergic receptor activity and, consequently, dose-limiting side effects, including orthostatic hypotension and hallucination, are frequent. Dexpramipexole exhibits significantly lower affinity for dopaminergic receptors, thereby making it unlikely to be associated with dopaminergic side effects. In clinical trials to date, dexpramipexole has been safe and well tolerated at doses up to 67-fold higher than the maximum recommended daily dose of pramipexole in patients with Parkinson's disease, and has demonstrated signs of neuroprotective benefit. This report summarizes the chemical and pharmacological properties of dexpramipexole and describes the potential utility of the drug in the pharmaceutical development pipeline.
LX-1031, being developed by Lexicon Pharmaceuticals, is an oral, small-molecule tryptophan 5-hydroxylase (TPH) inhibitor that reduces 5-HT synthesis peripherally. LX-1031 is being developed for the potential treatment of diarrhea-predominant irritable bowel syndrome (IBS-D), which is characterized by excess 5-HT. In preclinical studies, LX-1031 dose-dependently reduced expression of 5-HT in the duodenum, jejunum and ileum, but had no effect on brain 5-HT levels. In ascending single-dose and multiple-dose (14 day) phase I clinical trials in healthy volunteers, LX-1031 significantly reduced urinary 5-hydroxyindoleacetic acid (5-HIAA; a marker of 5-HT metabolism) levels, starting by day 5 and persisting over the duration of exposure. In a phase II clinical trial in patients with IBS-D, a 1000-mg qid dose of LX-1031 was associated with improved weekly global scores and stool consistency, and lower urinary 5-HIAA levels over a 28-day treatment period. LX-1031 was well tolerated in trials to date. In conclusion, LX-1031 appears promising for IBS-D. Optimal doses, efficacy in IBS clinical trials and safety need to be fully elucidated.
Remimazolam (CNS-7056) is a short-acting GABA(A) receptor agonist, under development by PAION, in collaboration with Japanese licensee Ono Pharmaceutical, as an intravenous sedative agent for potential use in day-case procedures, and the induction and maintenance of anesthesia. A member of the benzodiazapene class of drugs, the structure of remimazolam was modified to produce a drug that displays organ-independent metabolism. The incorporation of a carboxylic ester moiety into the benzodiazapene core of remimazolam renders it susceptible to non-specific tissue esterases and it is rapidly metabolized into its pharmacologically inactive metabolite CNS-7054. Preclinical studies in sheep demonstrated that remimazolam produced a more rapid onset of action, and a shorter duration of action, compared with midazolam. In a phase IIa clinical trial evaluating remimazolam as a procedural sedative for upper gastrointestinal endoscopy in patients, the time to recovery from sedation was shorter and more consistent with remimazolam, relative to midazolam. Because of its organ-independent metabolism and rapid and predictable onset and recovery, remimazolam appears to have potential advantages over other currently available short-acting sedatives.
Lu-AA21004, an oral, multimodal serotonergic agent, is currently under development by H Lundbeck and Takeda Pharmaceutical, for the potential treatment of depression and anxiety. Lu-AA21004 belongs to a novel chemical class of antidepressant agents, the bisarylsulfanyl amines, and possesses a novel pharmacological profile, with activity at serotonergic receptors 5-HT3, 5-HT7 and 5-HT1A, and also at the 5-HT transporter. Acute administration of Lu-AA21004 in rats inhibited the firing activity of serotonergic neurons of the dorsal raphe nucleus through 5-HT3 receptor blockade, with rapid recovery of firing activity upon cessation of treatment compared with an antidepressant of the SSRI class. Results from phase II clinical trials have reported improvement in depression and anxiety symptoms after 6 weeks of treatment. Lu-AA21004 was generally well tolerated, with adverse events related to sexual dysfunction occurring in a lower number of patients receiving Lu-AA21004 compared with venlafaxine. Phase III clinical trials with Lu-AA21004 in patients with major depressive disorder are underway and phase III trials in patients with generalized anxiety disorder have been completed. If initial outcomes from these clinical trials prove positive, Lu-AA21004 may pave the way for new multimodal therapies for the treatment of depression and anxiety.
The targeted molecular therapy for preventing heart failure and sudden cardiac death discussion session, organized by the Biochemical Pharmacology Discussion Group of the New York Academy of Sciences and held in New York, included topics covering new research developments in the field of heart failure. This conference report highlights selected presentations on GPCRs for heart failure, calcium and heart function, and mitochondrial targets in heart failure. A summary of the panel discussion is also provided.
Although the benefit of early ADME screening is widely recognized in the pharmaceutical industry, the implementation of this paradigm is often performed with insufficient resources and poor collaboration between functions. Dedicated and consistent integration efforts of ADME knowledge during the lead generation (LG) phase of drug discovery enables informed resourcing decisions and also increases the quality of initial starting points for discovery projects. To facilitate the efficient and consistent application of ADME resources to early projects at Eli Lilly and Co, a team of scientists was formed to provide dedicated ADME support to the LG phase of the discovery portfolio. This feature review discusses the working construct of the team, the general philosophy that was employed, and the outcomes of this endeavor.