AIMTo apply stochastic resonance algorithm (SRA) to quantitative analysis of weak chromatographic signal, which was embedded in the noise.

METHODSBased on the theory of stochastic resonance (SR), a simple and effective SRA has been established to improve analytical detection limits of chromatographic analysis, which apply to enhance the signal to noise ratio by the optimization of the parameters and Runge-Kutta method, was established. The method was used to quantitative analysis of phenazopyridine in human plasma by HPLC/UV. Meanwhile this method is compared with HPLC/MS.

RESULTSBy experimental chromatographic data sets, an excellent quantitative relationship between concentrations of phenazopyridine and their responses had been obtained. The concentration of phenazopyridine in plasma determined by HPLC/UV with SRA and HPLC/MS showed that there was no significant difference (P > 0.05) between the two methods.

CONCLUSIONThe new method was feasible.

Chromatography, High Pressure Liquid ; methods ; Humans ; Mass Spectrometry ; Noise ; Phenazopyridine ; blood ; Sensory Thresholds ; Spectrophotometry, Ultraviolet ; Stochastic Processes

PURPOSE: This study was designed to evaluate the analgesic effect, the side effects and the safety of using phenazopyridine HCl after cystoscopy, which is a drug that exerts a topical analgesic effect on the mucosa of the urinary tract. MATERIALS AND METHODS: The 63 patients who underwent cystoscopy at Pusan National University of Hospital from May 2004 to March 2005 were assigned to one of two groups (the experimental group had 35 patients and the control group had 30 patients). The experimental group was administrated antibiotics and phenazopyridine 200mg tid for 4 days and the control group was administrated antibiotics and digestives tid for 4 days. The analgesic effects were assessed with using the Numeric Pain Intensity Scale (NPIS) and the 4-point Categorical scale (CAT). RESULTS: The mean age of the phenazopyridine and control groups were 62.5+/-8.5 and 60.4+/-10.4 years, respectively, and follow-up period was 7 days. The amount of pain gradually decreased from the day 1 to day 7. The score of the NPIS in the experimental group was less than that of the control group, especially on day 1 and 2 after cystoscopy (p<0.05). The score of the CAT in the experimental group was less than that in the control group, especially on day 1 after cystoscopy (p<0.05). At for the degree of pain for consecutive cystoscopy in the same patients, 22 patients (84.7%) answered it was less painful, 3 (11.5%) answered it was the same as before and 1 (3.8%) answered it was more painful in the experimental group; 2 patient (8.7%) said it was less painful, 19 (82.6%) said it was the same as before and 2 (8.7%) said it was more painful in the control group. Side effects were not observed in all cases. CONCLUSIONS: We conclude that phenazopyridine HCl is effective for early acute pain relief following cystoscopy without side effects, and it is safe when used in combination with antibiotics.
Acute Pain ; Animals ; Anti-Bacterial Agents ; Busan ; Cats ; Cystoscopy* ; Follow-Up Studies ; Humans ; Mucous Membrane ; Pain Measurement ; Pain Perception* ; Phenazopyridine* ; Prospective Studies* ; Urinary Tract