Inhibition of Contractility of Isolated Caprine Detrusor by the Calcium Channel Blocker Cilnidipine and Reversal by Calcium Channel Openers.

Background: Cilnidipine is a fourth-generation calcium channel blocker that is clinically used to treat hypertension. It is a dihydropyridine that blocks L- and N-type calcium channels. The inhibitory effect of cilnidipine on isolated detrusor muscle contractility has not been studied. This study investigated the inhibitory effect of cilnidipine on isolated caprine (goat) detrusor muscle contractility and the reversal of the inhibition by calcium channel openers. Methods: Fourteen caprine detrusor strips were made to contract using 80 mM potassium chloride before and after addition of three concentrations (20, 40, and 60 µM) of cilnidipine. Two reversal agents, the L-type calcium channel opener FPL64716, and the N-type calcium channel opener GV-58, were investigated for their ability to reverse the inhibitory effect of 40 µΜ cilnidipine on potassium chloride-induced detrusor contractility. Results: Cilnidipine caused a dose-dependent and statistically significant inhibition of detrusor contractility at all concentrations of cilnidipine used (20, 40, and 60 µΜ). The inhibitory effect of 40 µM cilnidipine on detrusor contractility was significantly reversed by the addition of FPL64716 and GV-58. Conclusions: Cilnidipine inhibits the contractility of the isolated detrusor by blocking L- and N-type calcium channels. Cilnidipine could be evaluated for treating clinical conditions requiring relaxation of the detrusor such as overactive bladder.

Quantitative estimation of isoniazid content in the commercially available and government-supplied formulations.

BACKGROUND: Multi-drug resistant tuberculosis is on the rise, resulting in treatment failure. One potential reason for drug resistance is the substandard quality of manufactured antituberculous drugs. This study aims at finding out the difference in the quantity of isoniazid between government-supplied tablets and commercially available tablets. METHOD: Tablets from the single most commonly used brand of isoniazid manufactured by a pharmaceutical company and from RNTCP DOTS providing centre were obtained for the estimation of concentration using a spectrophotometer. The results were analysed using Un-paired Student's t-test. RESULTS: Of the 98 isoniazid tablets from each arm studied, none had the strength that deviated from the WHO limit of 90-110%, i.e. 270-330 mg. The mean strength ±SD of the commercial preparation of isoniazid tablets was found to be 295.16 ± 12.14. The mean strength ± SD of DOTS isoniazid tablets was found to be 298.69 ± 9.55. The difference observed in the strengths of isoniazid tablets between DOTS and commercial preparation was statistically insignificant (p = 0.1704). CONCLUSION: This method to estimate the strength of isoniazid tablets is inexpensive, relatively easy, and considerably accurate to perform, and hence can be employed in primary or secondary care centres to ensure the standard strengths of tablets dispensed from such centres.

Avanafil Inhibits the Contractility of the Isolated Caprine Detrusor Muscle.

CONTEXT: Avanafil is a smooth muscle relaxant that is clinically used to treat erectile dysfunction. It is an inhibitor of phosphodiesterase-5 (PDE5), the enzyme that catalyzes the metabolism of cyclic guanosine monophosphate (cGMP). The inhibitory effect of avanafil on isolated detrusor muscle contractility has not been studied. AIMS: This study investigated the inhibitory effect of avanafil on isolated caprine (goat) detrusor muscle contractility and the possible mechanisms involved. SETTINGS AND DESIGN: 80 mM potassium chloride (KCl)-induced contractility of the isolated goat detrusor was studied using a physiograph. MATERIALS AND METHODS: Ten caprine detrusor strips were made to contract using 80 mM KCl before and after addition of three concentrations (10, 30, and 60 µM) of avanafil. Three reversal agents, ODQ, a guanylyl cyclase inhibitor; glibenclamide, an adenosine triphosphate (ATP)-sensitive potassium channel blocker; and iberiotoxin, a calcium-sensitive potassium (BKCa) channel blocker, were investigated for their ability to reverse the inhibitory effect of 30 µM avanafil on KCl-induced detrusor contractility. STATISTICAL ANALYSIS USED: The nonparametric statistical test, Kruskal-Wallis test, was used for the analysis of the data. RESULTS: Avanafil caused a statistically significant inhibition of detrusor contractility at 30 and 60 µM concentrations. The inhibitory effect of 30 µM avanafil on detrusor contractility was significantly reversed by the addition of ODQ, glibenclamide, and iberiotoxin. CONCLUSIONS: Avanafil inhibits the contractility of the isolated detrusor by inhibiting PDE5, leading to raised cellular levels of cGMP. The raised levels of cGMP could have inhibited detrusor contractility by activating cGMP-dependent protein kinase, by opening ATP-sensitive potassium channels, and by opening BKCa. Avanafil could be evaluated for treating clinical conditions requiring relaxation of the detrusor like overactive bladder.

Inhibition of Spontaneous Contractility of Isolated Caprine Ureter by Flupirtine.

CONTEXT: Kv7 potassium channels are expressed in several types of smooth muscles and could mediate physiological responses in the tissues expressed. Flupirtine is an analgesic that acts by opening Kv7 potassium channels. It has been shown to inhibit the contractility of several types of isolated smooth muscle. AIMS: This study investigated the ability of flupirtine to inhibit the spontaneous contractility of isolated distal caprine (goat) ureter. SETTINGS AND DESIGN: Spontaneous contractility of the isolated goat ureter was recorded using a physiograph. MATERIALS AND METHODS: The ability of 1, 3, 10, 30, and 90 µM concentrations of flupirtine maleate to inhibit the spontaneous contractility of isolated distal goat ureter was investigated. The ability of the nonspecific potassium channel blocker 4-aminopyridine (4-AP; 1 mM) and the specific Kv7 channel blocker XE-991 (100 µM) to reverse the inhibitory effect of flupirtine on ureteric contractility was also investigated. STATISTICAL ANALYSIS USED: Both parametric and nonparametric statistical tests were used. RESULTS: At 10, 30, and 90 µM concentrations, flupirtine significantly inhibited the spontaneous contractility of the isolated goat ureter. The EC50 of flupirtine for a contact period of 10 min was 17.7 µM. The inhibitory effect of flupirtine on ureteric contractility was significantly reversed by 4-AP and XE-991. CONCLUSIONS: Flupirtine inhibits the spontaneous contractility of the isolated goat ureter by opening Kv7 channels.

Retraction: Association Between 5-HTR2C -759C/T (rs3813929) and -697G/C (rs518147) Gene Polymorphisms and Risperidone-Induced Insulin Resistance Syndrome in an Indian Population.

The above article from the Journal of Clinical Pharmacology, first published online on 22 September 2017 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement among the authors, the journal Editor in Chief, Joseph Bertino, and Wiley Periodicals, Inc. The retraction has been agreed upon due to the article having been submitted by the lead author without agreement from all co-authors. Having been alerted to this irregularity, the journal was also advised by the Senior Author of inaccuracies in the genotyping data. Reference Das, S., Dey, J. K., Prabhu SS, N., David, S., Kumar, A., Braganza, D. and Shanthi FX, M. (2017), Association Between 5-HTR2C -759C/T (rs3813929) and -697G/C (rs518147) Gene Polymorphisms and Risperidone-Induced Insulin Resistance Syndrome in an Indian Population. The Journal of Clinical Pharmacology. doi:10.1002/jcph.1012.