Phase characterization of indomethacin in binary solid dispersions with PVP VA64 or Myrj 52

In the present study the properties of binary solid dispersions made up of PVP VA64, Myrj 52 and indomethacin (IMC) are studied and characterized. The solid dispersions were prepared by dissolving the materials in dichloromethane, followed by solvent evaporation under reduced pressure at 55 degrees C in a rotavapor. Binary solid dispersions were characterized by standard and modulated temperature differential scanning calorimetry (MTDSC), thermogravimetry (TGA) and X-ray powder diffraction (XRPD). XRPD analysis showed that the initial IMC was in its gamma-form, and that it was transformed to the beta-form (reported to be a solvate) together with an amorphous fraction in the solid dispersions. A mixture of the beta-form and amorphous IMC was also obtained in the binary systems containing less than 30% polymer. IMC without adding polymer was subjected to the same experimental procedures as in the solid dispersions, and used as a model to characterize the solid-state transformations. The following order of transitions was observed: from the initial gamma-form, the beta-form was obtained together with an amorphous component, then the crystalline beta-form transforms into the alpha-form which melts and recrystallizes into the most stable gamma-form.     

Pharmacology of α7 nicotinic acetylcholine receptor mediated extracellular signal-regulated kinase signalling in PC12 cells

Background and purpose:

Neuronal nicotinic acetylcholine receptors (nAChR) can modulate cell survival and memory processing. The involvement of specific nAChR subtypes in downstream signalling events has been ill defined thus far, because of a lack of subtype-selective ligands. In this study, we investigated activation and modulation of α7 nAChR-mediated phosphorylation of extracellular signal-regulated kinases (ERK1/2) in PC12 cells, using selective agonists and positive allosteric modulators.

Experimental approach:

We used undifferentiated PC12 cells endogenously expressing α7 nAChR for both biochemical and functional studies. ERK phosphorylation changes were measured by using a novel In-Cell Western procedure. α7 nAChR-mediated Ca²⁺ signalling was determined by using the fluorometric imaging plate reader assay.

Key results:

Robust induction of ERK phosphorylation followed exposure of PC12 cells to the selective agonist PNU-282987 in the presence of the α7 nAChR modulator PNU-120596. ERK phosphorylation was transient and was attenuated by the selective antagonist methyllycaconitine. Consistent with allosteric modulation of α7 nAChRs, PNU-120596 enhanced both the agonist potency and efficacy in activating ERK. Moreover, α7 nAChR agonists could be quantitatively differentiated based on their potency in activating ERK signalling. The rank order of potencies correlated fairly well with the corresponding binding K_i values of these α7 nAChR agonists.

Conclusions and implications:

The present work extends previous observations demonstrating the involvement of α7 nAChRs in ERK1/2 phosphorylation in PC12 cells. The In-Cell Western procedure allowed a detailed investigation of α7 nAChR function and downstream ERK signalling in response to agonist and allosteric modulators.     

Expression of IL-1beta in supraspinal brain regions in rats with neuropathic pain

We examined mRNA expression of the pro-inflammatory cytokine IL-1beta in the brainstem, thalamus, and prefrontal cortex in two rat models of neuropathic pain. Rats received a neuropathic injury: spared nerve injury (SNI) or chronic constriction injury (CCI), sham injury, or were minimally handled (control). Neuropathic pain-like behavior was monitored by tracking tactile thresholds. SNI-injured animals showed a robust decrease in tactile thresholds of the injured foot, while CCI-injured animals did not show tactile threshold changes. Ten or 24 days after nerve injury, IL-1beta gene expression in the brain was determined by RT-PCR. IL-1beta expression changes were observed mainly at 10 days after injury in the SNI animals, contralateral to the injury side, with increased expression in the brainstem and prefrontal cortex. The results indicate that neuro-immune activation in neuropathic pain conditions includes supraspinal brain regions, suggesting cytokine modulation of supraspinal circuitry of pain in neuropathic conditions.     

Evaluating patients' experiences with individual physicians: a randomized trial of mail, internet, and interactive voice response telephone administration of surveys

BACKGROUND: There is increasing interest in measuring patients' experiences with individual physicians, and empirical evidence supports this area of measurement. However, the high cost of data collection remains a significant barrier. Survey modes with the potential to lower costs, such as Internet and interactive voice response (IVR) telephone, are attractive alternatives to mail, but their comparative response rates and data quality have not been tested. METHODS: We randomly assigned adult patients from the panels of 62 primary care physicians in California to complete a brief, validated patient questionnaire by mail, Internet (web), or IVR. After 2 invitations, web and IVR nonrespondents were mailed a paper copy of the survey ("crossover" to mail). We analyzed and compared (n = 9126) the response rates, respondent characteristics, substantive responses, and costs by mode (mail, web and IVR) and evaluated the impact of "crossover" respondents. RESULTS: Response rates were higher by mail (50.8%) than web (18.4%) or IVR (34.7%), but after crossover mailings, response rates in each arm were approximately 50%. Mail and web produced identical scores for individual physicians, but IVR scores were significantly lower even after adjusting for respondent characteristics. There were no significant physician-mode interactions, indicating that statistical adjustment for mode resolves the IVR effect. Web and IVR costs were higher than mail. CONCLUSIONS: The equivalence of individual physician results in mail and web modes is noteworthy, as is evidence that IVR results are comparable after adjustment for mode. However, the higher overall cost of web and IVR, as the result of the need for mailings to support these modes, suggests that they do not presently solve cost concerns related to obtaining physician-specific information from patients.     

Enzyme replacement therapy for mucopolysaccharidosis VI from 8 weeks of age–a sibling control study

McGill JJ, Inwood AC, Coman DJ, Lipke ML, de Lore D, Swiedler SJ, Hopwood JJ. Enzyme replacement therapy for mucopolysaccharidosis VI from 8 weeks of age–a sibling control study Mucopolysaccharidosis type VI (MPS VI) is a progressive, multisystem disorder caused by a deficiency of the lysosomal enzyme N‐acetylgalactosamine‐4‐sulphatase (ASB). Enzyme replacement therapy (ERT) has been shown to clinically benefit affected individuals greater than 6 years of age. This case control study of affected siblings assessed the safety, efficacy and benefits of ERT in children less than 5 years of age. Siblings, aged 8 weeks and 3.6 years, were treated weekly with 1 mg/kg recombinant human N‐acetylgalactosamine‐4‐sulphatase (rhASB) with an end‐point of 3.6 years. Clinical and biochemical parameters were monitored to assess the benefits of ERT. The treatment was well tolerated by both siblings. In the younger sibling, ERT was associated with the absence of the development of scoliosis and preserved joint movement, cardiac valves and facial morphology. The older sibling had a marked improvement in joint mobility and cardiac valve pathology and scoliosis slowed or stabilized. Corneal clouding and progressive skeletal changes were observed despite treatment. This study demonstrated a clear benefit of early initiation of ERT to slow or prevent the development of significant pathological changes of MPS VI. These results indicate that the earlier ERT is started, the greater the response.     

GSK1562590, a slowly dissociating urotensin-II receptor antagonist, exhibits prolonged pharmacodynamic activity ex vivo

BACKGROUND AND PURPOSE

Recently identified antagonists of the urotensin–II (U-II) receptor (UT) are of limited utility for investigating the (patho)physiological role of U-II due to poor potency and limited selectivity and/or intrinsic activity.

EXPERIMENTAL APPROACH

The pharmacological properties of two novel UT antagonists, GSK1440115 and GSK1562590, were compared using multiple bioassays.

KEY RESULTS

GSK1440115 (pK_i= 7.34–8.64 across species) and GSK1562590 (pK_i= 9.14–9.66 across species) are high affinity ligands of mammalian recombinant (mouse, rat, cat, monkey, human) and native (SJRH30 cells) UT. Both compounds exhibited >100-fold selectivity for UT versus 87 distinct mammalian GPCR, enzyme, ion channel and neurotransmitter uptake targets. GSK1440115 showed competitive antagonism at UT in arteries from all species tested (pA₂= 5.59–7.71). In contrast, GSK1562590 was an insurmountable UT antagonist in rat, cat and hUT transgenic mouse arteries (pK_b= 8.93–10.12 across species), but a competitive antagonist in monkey arteries (pK_b= 8.87–8.93). Likewise, GSK1562590 inhibited the hU-II-induced systemic pressor response in anaesthetized cats at a dose 10-fold lower than that of GSK1440115. The antagonistic effects of GSK1440115, but not GSK1562590, could be reversed by washout in rat isolated aorta. In ex vivo studies, GSK1562590 inhibited hU-II-induced contraction of rat aorta for at least 24 h following dosing. Dissociation of GSK1562590 binding was considerably slower at rat than monkey UT.

CONCLUSIONS AND IMPLICATIONS

Whereas both GSK1440115 and GSK1562590 represent high-affinity/selective UT antagonists suitable for assessing the (patho)physiological role of U-II, only GSK1562590 exhibited sustained UT residence time and improved preclinical efficacy in vivo.