Importance of 6-Thioguanine Nucleotide Metabolite Monitoring in Inflammatory Bowel Disease Patients Treated with Azathioprine.

The active metabolite of azathioprine, 6-thioguanine nucleotide (6-TGN) is the main component responsible for the immunosuppressive effect in treatment of inflammatory bowel disease (IBD). The aim of this study was to assess the correlation between the concentration of 6-thioguanine nucleotide and disease activity, azathioprine-related adverse effects and time duration of treatment in patients with inflammatory bowel disease. Thirty-four patients were included in this study. Type of disease, gender, time duration of therapy and adverse effects were recorded. Metabolite concentration was determined by high performance liquid chromatography. Twenty-one percent of patients have experienced an adverse effect, with leucocytopenia most commonly occurring (42.9%). More adverse effects were registered when patients were treated with azathioprine in a period of less than 3 months in comparison to the group of patients that have been under therapy between 3-12 months and more than 12 months (p˂0.05). Most of the patients that presented any adverse effect had high 6-TGN concentration (>450 pmol/8x108 Er). The mean value of 6-TGN metabolite concentration in IBD patients treated with azathioprine was 437.46 pmol/8x108 Er ± 198.82 pmol/8x108. The time duration of azathioprine treatment did not have any significant impact on the achieved 6-TGN concentration (p>0.05).Twenty patients (58.9%) had achieved remission after therapy initiation with azathioprine. More alertness is recommended to clinicians towards patients in the first 3 months of the therapy. Our study demonstrated that higher 6-TGN concentration is associated with azathioprine toxicity.

Spinal-Induced Hypotension in Preeclamptic and Healthy Parturients Undergoing Cesarean Section.

BACKGROUND: There is a widespread belief that spinal anaesthesia in patients with preeclampsia might cause severe hypotension and decreased uteroplacental perfusion. This study aimed to evaluate the incidence and severity of spinal induced-hypotension in preeclamptics and healthy parturients. METHODS: Total of 78 patients (40 healthy and 38 preeclamptic) undergoing a C-Section with spinal anaesthesia were included. Spinal anaesthesia was performed with a mixture of 8-9 mg isobaric 0.5% bupivacaine, 20 mcg fentanyl and 100 mcg morphine (total volume 2.2-2.4 ml). Blood pressures (BP)-SBP, DBP, MAP were recorded non-invasively before performing spinal anaesthesia and at 2.5 minutes after a spinal puncture. RESULTS: The BP falls (%) from baseline were significantly greater in the healthy parturients compared to those with preeclampsia (25.8% ± 10.1 vs 18.8% ± 17.0 for SBP, 28.5% ± 8.8 vs 22.5% ± 10.4 for DBP, and 31.2% ± 14.2 vs 18.2% ± 12.6% for MAP, p < 0.05). The incidence rate of hypotension in the preeclamptics was 25% compared to 53% in healthy parturients (p < 0.001). Higher doses of vasopressors both ephedrine (16.5 ± 8.6 vs 6.0 ± 2.0 mg) and phenylephrine (105 ± 25 mg) in the healthy women were required. There was no need for phenylephrine treatment in the preeclamptic group. CONCLUSION: This study showed that the incidence and severity of spinal-induced hypotension in preeclamptic patients are less than in healthy women. The use of low dose spinal anaesthesia also contributed to this statement.

Determination of Acyclovir in Human Plasma Samples by HPLC Method with UV Detection: Application to Single-Dose Pharmacokinetic Study.

BACKGROUND: The aim of this study is estimation of pharmacokinetic parameters: Cmax, tmax, t1/2, AUC0-t and AUC0-∞ with the two-way analysis of variance, single observation (ANOVA) for two preparations containing acyclovir. OBJECTIVE: In order to evaluate pharmacokinetic study of acyclovir, method for quantitative determination of acyclovir in human plasma should be simple, rapid and reproducible. Therefore, the method is developed, validated and applied for analysis of acyclovir in plasma samples obtained from healthy volunteers. MATERIAL AND METHODS: High performance liquid chromatographic (HPLC) method with UV-detection for the determination of acyclovir in human plasma is presented. This method involves protein precipitation with 20 % (V/V) perchloric acid. The chromatographic separation was accomplished on a reversed phase C8 column with a mobile phase composed of 0.1 % (V/V) triethylamine in water (pH 2.5). No internal standard is required. UV detection was set at 255 nm. The method was successfully applied for the evaluation of pharmacokinetic profiles of acyclovir tablets in 24 healthy volunteers. RESULTS: The validation results shows that proposed method is rugged, precise (RSDs for intra- and inter-day precision ranged from 1.02 to 8.37 %) and accurate (relative errors are less than 6.66 %). The calibration curve was linear in the concentration range of 0.1-2.0 µg/ml and the limit of quantification was 0.1 µg/ml. The Cmax, tmax and AUCs for the two products were not statistically different (p>0.05), suggesting that the plasma profiles generated by Zovirax were comparable to those produced by acyclovir manufactured by Jaka 80 company. CONCLUSION: Good precision, accuracy, simplicity, sensitivity and shorter time of analysis of the method makes it particularly useful for processing of multiple samples in a limited period of time for pharmacokinetic study of acyclovir.

Development of an HPLC method for the determination of nifedipine in human plasma by solid-phase extraction.

Nifedipine, a dihydropyridine calcium channel antagonist, is widely used in the treatment of hypertension and other cardiovascular disorders. A selective, sensitive and accurate high-performance liquid chromatographic method has been developed, validated and applied for determination of nifedipine in human plasma samples. A series of studies were conducted in order to investigate the effects of mobile phase composition, buffer concentration, mobile phase pH and concentration of organic modifiers, and to develop a convenient and easy-to-use method for quantitative analysis of nifedipine. The method involves solid-phase extraction on C18 cartridges. The chromatographic separation was accomplished on a Lichrocart Lichrospher 60 RP selectB column with a mobile phase composed of 0.020 mol/L KH2PO4 (pH 4.8) and acetonitrile (42:58, v/v). UV detection was set at 240 nm. The calibration curve was linear in the concentration range of 5.0-200.0 ng/mL for nifedipine in plasma and the limit of quantification was 5.0 ng/mL.