Sibutramine hydrochloride

Sibutramine hydrochloride is a novel 5-HT (serotonin) and noradrenaline reuptake inhibitor (SNRI). The IC50 for Sibutramine block of voltage-gated K+ channel (KV)4.3 is 17.3 μM.

In Vitro:Sibutramine is a novel 5-HT (serotonin) and noradrenaline reuptake inhibitor (SNRI). Sibutramine reduces the food intake of rodents and this effect is partially or completely reversed by pretreating with 5-HT or noradrenaline antagonists, indicating that both neurotransmitters are involved in sibutramine's hypophagic effect[1]. Sibutramine causes the concentration-dependent block of the KV1.3 and KV3.1 currents with IC50s of 3.7 and 32.7 μM, respectively. The steady-state currents of KV1.3 and KV3.1 are decreased by Sibutramine in a concentration-dependent manner with IC50s of 3.7±0.7 (n=6) and 32.7±5.0 μM (n=5), respectively[2].

In Vivo:Sibutramine (SIB) (5 mg/kg ip), which blocks the reuptake of both 5-hydroxytryptamine (5-HT) and noradrenaline (NA), also requires ARC pro-opiomelanocortin (POMC) neurons to achieve its appetitive effects in male and female mice. Sibutramine (5 mg/kg) suppresses 3-hour dark cycle food intake to a comparable extent in young adult and middle-aged male and female POMC-EGFP mice[3]. In normal Wistar rats, 3 mg/kg Sibutramine produces a marked (~30%) inhibition of food intake on the first day of dosing. Consistent with published data, the effects of Sibutramine on food intake diminished with time, although cumulative food intake over the 9-day study is significantly (P<0.001) lower in Sibutramine-treated (213.3±5.7 g) than in vehicle-treated (260.2±3.0 g) rats. Sibutramine also significantly reduces overall body weight gain (vehicle 30±2 g, Sibutramine 14±3 g; P<0.001)[4].

References:
[1]. Heal DJ, et al. Sibutramine: a novel anti-obesity drug. A review of the pharmacological evidence to differentiate it from d-amphetamine and d-fenfluramine. Int J Obes Relat Metab Disord. 1998 Aug;22 Suppl 1:S18-28; discussion S29. [2]. Kim SE, et al. Open channel block of A-type, kv4.3, and delayed rectifier K+ channels, KV1.3 and KV3.1, bySibutramine. J Pharmacol Exp Ther. 2007 May;321(2):753-62. [3]. Burke LK, et al. 5-HT obesity medication efficacy via POMC activation is maintained during aging. Endocrinology. 2014 Oct;155(10):3732-8. [4]. Turnbull AV, et al. Selective antagonism of the NPY Y5 receptor does not have a major effect on feeding in rats. Diabetes. 2002 Aug;51(8):2441-9.

Development and validation of sensitive methods for determination of sibutramine hydrochloride monohydrate and direct enantiomeric separation on a protein-based chiral stationary phase.[Pubmed:18567303]

J AOAC Int. 2008 May-Jun;91(3):572-9.

Sibutramine hydrochloride monohydrate, chemically 1-(4-chlorophenyl)-N,N-dimethyl-alpha-(2-methylpropyl) hydrochloride monohydrate (SB.HCI.H20), was approved by the U.S. Food and Drug Administration for the treatment of obesity. The objective of this study was to develop, validate, and compare methods using UV-derivative spectrophotometry (UVDS) and reversed-phase high-performance liquid chromatography (HPLC) for the determination of SB.HCI.H20 in pharmaceutical drug products. The UVDS and HPLC methods were found to be rapid, precise, and accurate. Statistically, there was no significant difference between the proposed UVDS and HPLC methods. The enantiomeric separation of SB was obtained on an alpha-1-acid glycoprotein column. The R- and S-sibutramine were eluted in < 5 min with baseline separation of the chromatographic peaks (alpha = 1.9 and resolution = 1.9).

Development and validation of high performance liquid chromatography method for analysis of sibutramine hydrochloride and its impurity.[Pubmed:18390441]

Pak J Pharm Sci. 2008 Apr;21(2):121-4.

A simple, Precise, Rapid reproducible and selective reverse phase HPLC method has been developed for the estimation of Sibutramine hydrochloride monohydrate and its Impurity in Bulk as well as Formulation. The analyte was resolved by using Mobile phase (Sodium Dihydrogen phosphate and Acetonitrile) at the flow rate of 1.0 Ml/Min. on Isocratic HPLC system consisting of Jasco Make UV visible Detector of model UV 1575 & Jasco make HPLC pump of model PU 1580. An ODS C- 8 RP Column (4.6mm ID, 250mm L, particle size 5 Micron, at wavelength of 230 nm.

Calorimetric, FTIR and 1H NMR measurements in combination with DFT calculations for monitoring solid-state changes of dynamics of sibutramine hydrochloride.[Pubmed:22826266]

J Pharm Sci. 2012 Oct;101(10):3799-810.

Two forms of Sibutramine hydrochloride, monohydrate and anhydrous, have been investigated by calorimetric methods, Fourier transform infrared (FTIR) absorption and (1) H nuclear magnetic resonance (NMR) measurements as well as by density functional theory (DFT) of vibrational frequencies and infrared intensities, calculations of steric hindrances and Monte Carlo simulations. The results of FTIR spectra combined with DFT calculations permitted identification of the bands corresponding to the dynamics and vibrations of water molecules. NMR study and Monte Carlo simulations revealed the occurrence of reorientation jumps of the methyl groups in sibutramine cation and also revealed that the reorientation of isopropyl group is possible only in sibutramine monohydrate hydrochloride. The hydration of Sibutramine hydrochloride causes a change in the conformation of sibutramine cation.

[Spectroscopic studies on the binding of sibutramine hydrochloride and bovine serum albumin].[Pubmed:16671551]

Yao Xue Xue Bao. 2006 Feb;41(2):175-8.

AIM: To study the binding of Sibutramine hydrochloride (SH) and bovine serum albumin (BSA) in physiological condition by spectroscopic method. METHODS: The quenching mechanism of the fluorescence of bovine serum albumin by Sibutramine hydrochloride was studied with the fluorescence and the absorption spectroscopy. The binding constants K and the number of binding sites were determined at different temperatures according to Scatchard equation and the main binding force was discussed by thermodynamic equations. The effect of the drug on bovine serum albumin conformation was also studied by using synchronous fluorescence spectroscopy. RESULTS: The quenching mechanism of Sibutramine hydrochloride to bovine serum albumin was static quenching. The binding constants K at 8 degrees C, 25 degrees C, 37 degrees C were 1.21 x 10(5), 8.31 x 10(4), 6.97 x 10(4) L x mol(-1) with one binding site, respectively. The thermodynamic parameters of the reaction were deltaH = -9.70 kJ x mol(-1), deltaS = 56.41 J x mol(-1) x K(-1). CONCLUSION: The binding force is electrostatic interaction. Sibutramine hydrochloride can be deposited and transported by serum protein in vivo. Sibutramine hydrochloride has nearly no effect on the serum protein conformation.

In vivo criteria to differentiate monoamine reuptake inhibitors from releasing agents: sibutramine is a reuptake inhibitor.[Pubmed:9353373]

J Pharmacol Exp Ther. 1997 Nov;283(2):581-91.

Because monoamine reuptake inhibitors and releasing agents both increase extracellular neurotransmitter levels, establishing in vivo experimental criteria for their classification has been difficult. Using microdialysis in the hypothalamus of unanesthetized rats, we provide evidence that serotonin- (5-HT) selective and nonselective reuptake inhibitors can be distinguished from the 5-HT-releasing agent fenfluramine by four criteria: 1) Systemic fenfluramine produces a much greater increase in 5-HT than the reuptake inhibitors. 2) The 5-HT somatodendritic autoreceptor agonist, (+/-)-8-hydroxy-(dipropylamino)tetralin (8-OH-DPAT), attenuates the increase in 5-HT produced by reuptake inhibitors, but not by fenfluramine. 3) The large increase in 5-HT produced by infusion of reuptake inhibitors into the hypothalamus is attenuated by their systemic administration. However, systemic injection of fenfluramine during its local infusion does not attenuate this increase. 4) Reuptake inhibitor pretreatment attenuates fenfluramine-induced increases in 5-HT. According to these criteria, the in vivo effects of the novel antiobesity drug sibutramine are consistent with its characterization as a 5-HT reuptake inhibitor and not a 5-HT releaser. Thus, sibutramine produced increases in hypothalamic 5-HT similar in magnitude to the effects of the known reuptake inhibitors, and the increase was attenuated by 8-OH-DPAT. Also, sibutramine attenuated fenfluramine-induced 5-HT release. Systemic administration of sibutramine failed to attenuate the increase in 5-HT produced by its local infusion, suggesting that this criterion is not applicable to compounds with low affinity for the 5-HT transporter.

Comparison of the effects of sibutramine and other monoamine reuptake inhibitors on food intake in the rat.[Pubmed:9283714]

Br J Pharmacol. 1997 Aug;121(8):1758-62.

1. The effects of the potent 5-hydroxytryptamine (5-HT) and noradrenaline reuptake inhibitor (serotonin-noradrenaline reuptake inhibitor, SNRI), sibutramine, on the cumulative food intake of freely-feeding male Sprague-Dawley rats during an 8 h dark period were investigated and compared to those of the selective 5-HT reuptake inhibitor (selective serotonin reuptake inhibitor, SSRI), fluoxetine; the selective noradrenaline reuptake inhibitor, nisoxetine; the 5-HT and noradrenaline reuptake inhibitors, venlafaxine and duloxetine; and the 5-HT releaser and 5-HT reuptake inhibitor, (+)-fenfluramine. 2. Sibutramine (3 and 10 mg kg-1, p.o.) and (+)-fenfluramine (1 and 3 mg kg-1, p.o.) produced a significant, dose-dependent decrease in food intake over the 8 h dark period. These responses became apparent within the first 2 h following drug administration. 3. Fluoxetine (3, 10 and 30 mg kg-1, p.o.), and nisoxetine (3, 10 and 30 mg kg-1, p.o.) had no significant effect on food intake during the 8 h dark period. However, a combination of fluoxetine and nisoxetine (30 mg kg-1, p.o., of each) significantly decreased food intake 2 and 8 h after drug administration. 4. Venlafaxine (100 and 300 mg kg-1, p.o.) and duloxetine (30 mg kg-1, p.o.) also significantly decreased food intake in the 2 and 8 h following drug administration. 5. The results of this study demonstrate that inhibition of 5-HT and noradrenaline reuptake by sibutramine, venlafaxine, duloxetine, or by a combination of fluoxetine and nisoxetine, markedly reduces food intake in freely-feeding rats and suggest that this may be a novel approach for the treatment of obesity.