SIB-1757 and SIB-1893: selective, noncompetitive antagonists of metabotropic glutamate receptor type 5.
(1/12)
Cell lines expressing the human metabotropic glutamate receptor subtype 5a (hmGluR5a) and hmGluR1b were used as targets in an automated high-throughput screening (HTS) system that measures changes in intracellular Ca2+ ([Ca2+]i) using fluorescence detection. This functional screen was used to identify the mGluR5-selective antagonist, SIB-1757 [6-methyl-2-(phenylazo)-3-pyridinol], which inhibited the glutamate-induced [Ca2+]i responses at hmGluR5 with an IC50 of 0.37 microM compared with an IC50 of >100 microM at hmGluR1. Schild analysis demonstrated a noncompetitive mechanism of inhibition. Pharmacophore mapping was used to identify an additional compound, SIB-1893 [(E)-2-methyl-6-(2-phenylethenyl)pyridine], which was also shown to block glutamate-induced increases in [Ca2+]i at hmGluR5 with an IC50 of 0.29 microM compared with an IC50 of >100 microM at hmGluR1. SIB-1757 and SIB-1893 showed little or no activity when tested for agonist and antagonist activity at the other recombinant human mGluR subtypes, alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid, kainate, and N-methyl-D-aspartate receptors. In rat neonatal brain slices, SIB-1757 and SIB-1893 inhibited (S)-3,5-dihydroxyphenylglycine (DHPG)-evoked inositol phosphate accumulation in hippocampus and striatum by 60% to 80%, with a potency similar to that observed on recombinant mGluR5. However, in the cerebellum, a brain region with low mGluR5 expression, SIB-1757 failed to inhibit DHPG-evoked inositol phosphate accumulation. In cultured rat cortical neurons, SIB-1757 and SIB-1893 largely inhibited DHPG-evoked [Ca2+]i signals, revealing a population of neurons that were less sensitive to SIB-1757 and SIB-1893. This is the first description of highly selective, noncompetitive mGluR5 antagonists. These compounds will be useful tools in evaluating the role of mGluR5 in normal physiology and in animal models of disease. (+info)
Usage patterns of over-the-counter phenazopyridine (pyridium).
(2/12)
OBJECTIVES: Little is known about how the public uses formerly prescription medications that are available over-the-counter (OTC). This study examines whether consumers inappropriately use and substitute a recently widely distributed OTC urinary analgesic, phenazopyridine, for provider care. DESIGN/SETTING: We conducted a cross-sectional survey of a stratified cluster random sample of OTC phenazopyridine purchasers (N = 434) in 31 Los Angeles retail pharmacies over 5 months. Recruited by shelf advertisements, participants were 18 years or older who purchased a phenazopyridine product. Each completed a 25-item self-administered anonymous questionnaire. Inappropriate use was defined as 1) having medical contraindications to phenazopyridine, or 2) not having concurrent antibiotic and/or provider evaluation for the urinary symptoms. RESULTS: The survey response rate was 58%. Fifty-one percent of the respondents used OTC phenazopyridine inappropriately, and 38% substituted it for medical care. Multiple logistic regression analyses revealed that inappropriate use was correlated with having little time to see a provider (odds ratio [OR], 1.57; 95% confidence interval [95% CI], 1.26 to 1.96), receiving friend's or family's advice (OR, 1.25; 95% CI, 1.05 to 1.47), having prior urinary tract infections (OR, 0.49; 95% CI, 0.30 to 0.80), having used prescription phenazopyridine, (OR, 0.40; 95% CI, 0.25 to 0.63), and having back pain (OR, 0.34; 95% CI, 0.16 to 0.74). Similar correlates were found in those who substituted OTC phenazopyridine for provider care. Respondents with incorrect knowledge about phenazopyridine's mode of action had 1.9 times greater odds of inappropriate use and 2.2 times greater odds of substitution than those who had correct knowledge about this drug. CONCLUSION: Inappropriate use of OTC phenazopyridine appears common. Increasing the public's knowledge about reclassified drugs may help to mitigate this problem. (+info)
Consumer knowledge of over-the-counter phenazopyridine.
(3/12)
BACKGROUND: Effective use of over-the-counter (OTC) medications depends on purchasers' knowledge of their indications. This study examines consumer knowledge regarding the urinary tract analgesic phenazopyridine, which recently became available without prescription. METHOD: We conducted a cross-sectional survey of a stratified cluster random sample of purchasers of OTC phenazopyridine (N = 434) in 31 Los Angeles retail pharmacies. RESULTS: The response rate was 58%. Only 42% correctly characterized the likely cause of their symptoms, and only 57% correctly characterized the action of the drug. Worse consumer knowledge was associated with nonwhite race, first-time use, and less contact with health providers. CONCLUSION: Many consumers possess poor knowledge about phenazopyridine, potentially leading to undertreatment, especially in groups with worse access to care. (+info)
Neurogenic bladder and chronic urinary retention associated with MDMA abuse.
(4/12)
INTRODUCTION: The use of 3,4-methylenedioxymethamphetamine (MDMA, known as "ecstasy"), a synthetic amphetamine and "club drug," has been associated with acute, transient urinary retention. We report a case of neurogenic bladder and chronic urinary retention associated with MDMA abuse. CASE REPORT: A 21-year-old male presented to the emergency department (ED) because he had abdominal pain and difficulty urinating. He had experienced difficulty in initiating urination over the past 1.5 months, with periods of 24 to 36 hours between voids and large volumes of urine. The patient had a chronic pattern of MDMA use, taking 4 tablets/day for 3 months. Two weeks before coming to the ED, he had been admitted to an inpatient drug rehabilitation center. During the time since that admission, the patient had visited EDs repeatedly for insertion and removal of Foley catheters to relieve the urinary retention until he could be admitted to a urologic service. Cystometrogram was abnormal, finding no sensation of bladder fullness after instillation of 350 mL of saline and inability to generate a voluntary voiding pressure. Cystoscopy revealed no outlet obstruction. The findings were consistent with neurogenic bladder. The patient was given prescriptions for bethanecol and phenazopyridine, and told to continue a 10-day course of sulfamethoxazole/trimethoprim for urinary tract infection. He was discharged with a Foley catheter in place. Symptoms of urinary retention persisted at 1-year follow-up, despite self-catheterization and complete cessation of MDMA use. CONCLUSION: Chronic MDMA use may lead to neurogenic bladder and chronic urinary retention. (+info)
Determination of phenazopyridine in human plasma by GC-MS and its pharmacokinetics.
(5/12)
A sensitive, selective, and simple gas chromatography-mass spectrometry method is developed for quantitation of phenazopyridine (PAP) in human plasma using internal standard (diazepam). PAP and IS are extracted from plasma by liquid-liquid extraction and analyzed on a DB-5MS column with mass selective detector. Excellent linearity is found between 5-500 ng/mL (r = 0.9992, n = 7) for PAP in human plasma. The limit of detection is 0.3 ng/mL. Intra- and Inter-day precisions expressed as the relative standard deviation for the method are 1.37-6.69% and 1.24-6.01%, respectively. Extraction efficiency is more than 90%, and recoveries are in the range of 92.65-96.21%. This method is successfully applied for the pharmacokinetics and bioequivalence of 2 formulations of PAP in 18 healthy male volunteers who received a single 200 mg dose of each formulation. (+info)
Highly regio- and stereoselective synthesis of (Z)-trisubstituted alkenes via propyne bromoboration and tandem Pd-catalyzed cross-coupling.
(6/12)
Site-selective functionalizations of complex small molecules can generate targeted derivatives with exceptional step efficiency, but general strategies for maximizing selectivity in this context are rare. Here, we report that site-selectivity can be tuned by simply modifying the electronic nature of the reagents. A Hammett analysis is consistent with linking this phenomenon to the Hammond postulate: electronic tuning to a more product-like transition state amplifies site-discriminating interactions between a reagent and its substrate. This strategy transformed a minimally site-selective acylation reaction into a highly selective and thus preparatively useful one. Electronic tuning of both an acylpyridinium donor and its carboxylate counterion further promoted site-divergent functionalizations. With these advances, we achieve a range of modifications to just one of the many hydroxyl groups appended to the ion channel-forming natural product amphotericin B. Thus, electronic tuning of reagents represents an effective strategy for discovering and optimizing site-selective functionalization reactions. (+info)
Drug-dependent and non-drug-dependent antiplatelet antibody in drug-induced immunologic thrombocytopenic purpura.
(8/12)
The mechanism of drug-dependent immunologic thrombocytopenic purpura (DITP) was investigated by studying the sera of four patients with classic DITP (two with quinidine-, one with acetaminophen-, and one with phenazopyridine-dependent antiplatelet antibody) using a solid-phase radioimmunoassay with 125I-staphylococcal protein A. Two forms of antiplatelet antibody could be demonstrated: one that required drug to bind to platelets and one that bound to platelets in the absence of drug. Drug-dependent antiplatelet antibody required the simultaneous addition of drug and the Fc domain of the drug-dependent IgG molecule for binding to platelets. It did not require serum complement or factor VIII-related antigen for binding to platelets. Drug-dependent binding of antibody to platelets was saturation-dependent. Non-drug-dependent antiplatelet antibody of two patients (one with quinidine-induced thrombocytopenia and the other with acetaminophen-induced thrombocytopenia) reacted with autologous platelets as well as with homologous platelets, indicating that they were autoantibodies. Both autoantibodies had disappeared when their sera were tested 23 and 138 days, respectively, after withdrawal of their initial positive sera. Non-drug-dependent antiplatelet antibody binding could be demonstrated with the F(ab')2 fragment of the purified IgG of the serum of the second patient with quinidine DITP, who did not have detectable alloantibodies against HLA. None of the four patients with non-drug-dependent antiplatelet antibody had a past or present history of autoimmune thrombocytopenic purpura. (+info)