The aim of the present work was to validate a paper chromatography system as an alternative way to determine the radiochemical purity of Na 18 F. Methods: The evaluated parameters were specificity, limit of quantification, measurement interval, linearity, precision, accuracy, and robustness. Results: The proposed method proved to be linear (P . 0.05; r 2 5 1.000), precise (relative SD, 8.6%), accurate (mean recovery, 95.9%; relative SD, 1.5%-1.8%), and robust under different conditions since no influence of the operative variables on the chromatographic performance was observed. Conclusion: This system can be used as a reliable alternative method to determine the radiochemical purity of Na 18 F samples that can be easily performed in PET radiopharmacies at low cost. TheuseofNa 18 F for bone scintigraphy dates back to the early 1960s (1). However, the unavailability of clinical cyclotrons and the development of 99m Tc-labeled agents for bone scintigraphy brought about the prompt replacement of Na 18 F with 99m Tc agents for clinical use (2). Some decades later, Na 18 F was rediscovered when, in 2000, the Food and Drug Administration approved it as a radiopharmaceutical for bone scintigraphy as part of its modernization in the handling of new drug applications (3). Since then, many reports have proposed the use of this agent as a sensitive and specific radiopharmaceutical for detection of benign and malignant osseous abnormalities that also allows the regional characterization of lesions in metabolic bone diseases (4,5).Na 18 F is a cyclotron-produced radiopharmaceutical, and the only reported and validated methodology for determining its radiochemical purity (RP) is high-performance liquid chromatography, which requires special equipment (6-8). Nevertheless, previous studies demonstrated the efficacy of a paper chromatography method for the RP determination of Na 18 F (9). This work was performed to investigate the possibility of applying the paper chromatography method as an alternative to high-performance liquid chromatography for 18 F-fluoride RP analysis. MATERIALS AND METHODS Na 18 F Production18 F-fluoride was produced on an 18-MeV cyclotron, Cyclone 18/9 (IBA), by the 18 O(p,n) 18 F nuclear reaction. The niobium target (with yield of 8.7 GBq/mA at saturation) was filled with 2 mL of enriched 18 O water, which was irradiated with protons for 10 min at anintensity of 40 mA. The solution containing 18 F 2 was transferred into an automatic synthesis module, Synthera (IBA), prepared with a commercial reagent kit and accessories for Na 18 F production. 18 F-fluoride ions were trapped in an anion exchange column (Sep-Pak Light Accell Plus QMA; Waters Corp.) and were theneluted with a 0.9% NaCl solution. Finally, the resulting 15 mL of Na 18 F were dispensed into a sterile, pyrogen-free vial through a 0.22-mm filter (Millipore) in a dispensing unit (Dispensing Hot Cell; Becquerel and Sievert Co., Ltd.). Physicochemical Quality ControlRadionuclidic purity was evaluated by g-ray spectrometry (PX4 TeCd detector; Ampt...
Dissolution studies have become matter of great significance because, in most cases, drug dissolution is the rate-limiting step in the absorption process. As occurs with solid oral dosage forms, heterogeneous disperse systems (suspensions) could also have some problems with their in vitro dissolution.The dissolution behavior of four different brands of cefadroxil extemporaneous suspensions available in the Argentinian market was evaluated. The deliverable volume, pH, visual appearance, uniformity of dosage units, and assay were also studied.Powders for oral suspension were stored under different aging conditions. Samples at room temperature and refrigerated conditions were taken at several time points to carry out the dissolution stability study during the expiration period of the reconstituted form. Marked differences were recorded with respect to in vitro dissolution behavior between the different products under evaluation.
Simple, sensitive, and economical simultaneous volumetric and HPLC methods for the determination of pridinol mesylate in raw material have been developed. The volumetric method is based on the reaction of pridinol with sodium lauryl sulphate in diluted sulphuric acid. Dimethyl yellow was used as indicator to detect the end point of the titration in aqueous/organic layer. The HPLC method for the determination of pridinol mesylate employs a reverse phase C18 column at ambient temperature with a mobile phase consisting of acetonitrile: 0.05 M potassium dihydrogen phosphate, pH adjusted to 5.0 (1 : 2, v/v). The flow rate was 0.8 mL/min. Quantitation was achieved with UV detection at 258 nm based on peak area. Both methods were found to be suitable for the quality control of pridinol mesylate in raw material.
Myasthenia gravis is an autoimmune disease that destroys key components of the neuromuscular system. The most common therapy uses reversible inhibitors of cholinesterase activity, such as pyridostigmine bromide (PB). The nature of this illness implies that we must be sure that all available PB immediate-release tablets produce the same therapeutic response.The aim of this study was to analyze PB immediate-release formulations provided by pharmacies in MERCOSUR countries A, B, and C. The formulations, which were produced in different manufacturing plants of the same multinational company, were analyzed following USP 29 specifications.The products fulfilled the assay, uniformity of dosage units, and dissolution test in S 2 stage. Dissolution profiles were carried out following EMEA and FDA regulations, and the similarity factor (f 2 ) was applied to A and C but not B, as this one did not fulfill the dissolution requirements. Pyridostigmine bromide tablets from countries A and C are considered to be similar and could be interchangeable. Formulation B exhibited such different dissolution behavior that its interchangeability is discouraged, as well as its introduction in countries A and C from the manufacturing country B.
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