RESUMO
Piroxicam [Pir] and tenoxicam [Ten] are specified as nonsteriodal anti-inflammatory drugs. They are used in the symptomatic management of osteoarthritis, rheumatoid arthritis and in short term management of soft-tissue injury. Therefore, their reactions with oxidants, Iodate and N-bromosuccinamide [NBS] are suggested, discussed and used for microdeterminations of these essential biomedical drugs. A sensitive Spectrophotometric method has been suggested and used in comparison with a potentiometric one to follow these reactions mechanisms aiming to apply them in microdetermination of piroxicam [Pir] and tenoxicam [Ten]. No interference from excipients was observed in both techniques. The Spectrophotometric procedure was better than the potentiometric one, because of the sensitivity of the former to detect lower concentration ranges [50 to 1100 micro g ml[-1]] of the pure standard drugs and the detection of high concentration range [300 to 3980 micro g ml[-1]] by the latter. The high molar absorptivity [e = 0.25-0.29 x 10[3] L.mol[-1] cm[-1]] and Sandell sensitivity [1.2 - 13 micro g cm[-2]] refer to the high selectivity of the Spectrophotometric method. The between -day precision of the potentiometric procedure refers to the greater stability and good reliability of this procedure in high concentration [% recovery = 99 to 102%]. These procedures were applied for successful microdetermination of Pir and Ten in many pharmaceutical preparations, such as tablets and capsules. The values of SD [0.03 to 0.6 for five replicates] and RSD [0.6 to 1.2%] refer to reproducibility and precision of the applied procedures. The results of analyses of these drugs were compared with those obtained by the application of the official method using Ringbom, t-test and f-test. These results gave t- value of 2.776 and f-value of 6.31 at 95% confidence level. The obtained results also refer to the robustness of the proposed procedures