(R)-(+)-Propranolol hydrochloride

Physico-chemical characterisation of the modifications I and II of (R,S) propranolol hydrochloride: solubility and dissolution studies.[Pubmed:10703984]

J Pharm Biomed Anal. 1999 Nov;21(2):299-309.

The crystallisation conditions and the physicochemical properties of the modifications I and II of (R,S) propranolol hydrochloride were investigated. Detailed methods of preparation of the two forms were described. Data from FTIR spectroscopy, X-ray powder diffraction, thermal analysis, solubility and dissolution studies were used for the identification and the characterisation of the two forms. The forms I and II were easily differentiated by their IR spectra, X-ray patterns and thermal behaviour. The two polymorphs were found to be enantiotropically related to each other. Their stability was followed at room temperature over a period of 1 year and under different conditions of temperature, grinding and compression to verify the tendency to solid solid transition and to study the existence range of the two forms. The equilibrium solubilities of the two polymorphs in n-octanol were determined as well as their dissolution profiles as pellets in aqueous medium. These studies showed that form I, the less thermodynamically stable, was more soluble (by more than 34%) and dissolved faster than form II in agreement with the thermodynamic rules (A. Burger, R. Ramberger, Mikrochim. Acta II (1979) 259-271).

Effects of (R)- and (S)-propranolol hydrochloride enantiomers on the resonance Rayleigh scattering spectra with erythrosine B as probe and their analytical applications.[Pubmed:25618732]

Talanta. 2015 Mar;134:754-760.

Propranolol, a chiral drug with two configurations, i.e., (R)-propranolol hydrochloride (RPH) and (S)-propranolol hydrochloride (SPH), has racemes that can be used in clinical diagnosis due to their synergistic effects. SPH has a beta-receptor blocking effect, and RPH has an antiarrhythmic effect. In pH 4.6 Britton-Robinson (BR) buffer solution, both RPH and SPH can react with erythrosine B to form 1:1 ion-association complexes. In the SPH-Ery B reaction system, a remarkable enhancement of the resonance Rayleigh scattering (RRS) signal located at 338 nm was observed. However, a similar phenomenon was not obvious and was unstable in the RPH-Ery B reaction system. Based on this result, a simple, novel and sensitive method for the determination of SPH was proposed based on the RRS technique. The linear range and limit of detection were 0.0680~4.0 microg mL(-1) and 20.6 ng mL(-1), respectively. Additionally, the spectroscopic approaches of frequency doubling scattering (FDS) and second-order scattering (SOS) were also proposed for SPH detection in this article. The interaction information regarding the mechanism of the reaction, suitable reaction conditions, influencing factors and the effects of mixed solutions were our investigation aims. The method had been applied to the determination of SPH in fresh serum and urine samples of healthy human subjects with satisfactory results.

The biological properties of the optical isomers of propranolol and their effects on cardiac arrhythmias.[Pubmed:19108278]

Br J Pharmacol. 1968 Sep;34(1):43-55.

1. The optical isomers of propranolol have been compared for their beta-blocking and antiarrhythmic activities.2. In blocking the positive inotropic and chronotropic responses to isoprenaline, (+)-propranolol had less than one hundredth the potency of (-)-propranolol. At dose levels of (+)-propranolol which attenuated the responses to isoprenaline, there was a significant prolongation of the PR interval of the electrocardiogram.3. The metabolic responses to isoprenaline in dogs (an increase in circulating glucose, lactate and free fatty acids) were all blocked by (-)-propranolol. (+)-Propranolol had no effect on fatty acid mobilization but significantly reduced the increments in both lactate and glucose.4. Both isomers of propranolol possessed similar depressant potency on isolated atrial muscle taken from guinea-pigs.5. The isomers of propranolol exhibited similar local anaesthetic potencies on an isolated frog nerve preparation at a level approximately three times that of procaine. The racemic compound was significantly less potent than either isomer.6. Both isomers of propranolol were capable of preventing adrenaline-induced cardiac arrhythmias in cats anaesthetized with halothane, but the mean dose of (-)-propranolol was 0.09+/-0.02 mg/kg whereas that of (+)-propranolol was 4.2+/-1.2 mg/kg. At the effective dose level of (+)-propranolol there was a significant prolongation of the PR interval of the electrocardiogram. Blockade of arrhythmias with both isomers was surmountable by increasing the dose of adrenaline.7. Both isomers of propranolol were also capable of reversing ventricular tachycardia caused by ouabain in anaesthetized cats and dogs. The dose of (-)-propranolol was significantly smaller than that of (+)-propranolol in both species but much higher than that required to produce evidence of beta-blockade.8. The implications of these results are discussed.