pH-independent release of propranolol hydrochloride from HPMC-based matrices using organic acids

Propranolol HC1, a widely used drug in the treatment of cardiac arrhythmias and hypertension, is a weak basic drug with pH-dependent solubility that may show release problems from sustained release dosage forms at higher pH of small intestine. This might decrease drug bioavailability and cause variable oral absorption. Preparation of a sustained release matrix system with a pH-independent release profile was the aim of the present study. Three types of organic acids namely tartaric, citric and fumaric acid in the concentrations of 5, 10 and 15% were added to the matrices prepared by hydroxypropyl methylcellulose [HPMC] and dicalcium phosphate. The drug release studies were carried out at pH 1.2 and pH 6.8 separately and mean dissolution time [MDT] as well as similarity factor [f[2]] were calculated for all formulations. It was found that incorporation of 5 and 10% tartaric acid in tablet formulations with 30% HPMC resulted in a suitable pH-independent release profiles with significant higher f[2] values [89.9 and 87.6 respectively] compared to acid free tablet [58.03]. The other two acids did not show the desirable effects. It seems that lower pK[a] of tartaric acid accompanied by its higher solubility were the main factors in the achievement of pH-independent release profiles

Radiation dose to the nuclear medicine nurses

Background: People who have been administrated radiopharmaceuticals could be a source of radiation to their relatives, medical nurses, and people who are in contact with them. The aim of this work was to estimate radiation dose received by nuclear medicine nurses

Materials and Methods: In this study, the dose rates at various distances of 5 - 100 cm from 70 patients, who were administered diagnostic amounts of 201Tl-Chloride and 99mTc-MIBI, were measured using an ionization chamber. For determination of external radiation dose to the nurses, three different time intervals were used for measurements

Results: The maximum values of external dose rates of 201Tl and 99mTc-MIBI were 11.2 microSv/h +/-2.3 and 43.1microSv/h +/-11.9 respectively, at 5cm from the patients. Significant exposure from patients after injection of 99mTc-MIBI was limited to the day of administration. Departure dose rate of 201Tl fell gradually; so, it became significant by 3 days after administration. Maximum and average absorbed dose of nuclear medicine staff from 201Tl, was 4.6 and 2.7 microSv/h, and for 99mTc-MIBI was 18.1 and 9.8 microSv/h in each scan

Conclusion: Significant exposure from the patients is limited to the few hours after administration, therefore patients should be recommended to urinate frequently before leaving the nuclear medicine department