Severe acute intoxication with yohimbine: Four simultaneous poisoning cases.

Yohimbine is an indole alkaloid from the leaves and bark of the Pausinystalia johimbe tree that has acquired an enviable reputation in treating erectile dysfunction. This report presents four simultaneous severe poisoning/death cases caused by yohimbine. The test samples comprised the venous blood of four middle-aged men (aged 47-65) who were suspected of poisoning; one of the men died due to ineffective rescue. Ethanol concentration determination and toxicological routine screening were performed using gas chromatography with flame ionization detection (GC-FID) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). A specific LC-MS/MS method was developed to quantify yohimbine, which showed concentrations of 459, 249, and 301ng/mL in three poisoned blood samples and concentrations as high as 5631ng/mL in the deceased. Moreover, the deceased's autopsy ruled out death from trauma and previous illness, and no other common toxic components were detected in his blood. Therefore, yohimbine poisoning appears to be the most likely cause of death. As a type of alkaloid that can be employed in the treatment of clinical diseases and additives for supplements, the danger of yohimbine should be of widespread concern in society.

Adjustment of Conditions for Combining Oxybutynin Transdermal Patch with Heparinoid Cream in Mice by Analyzing Blood Concentrations of Oxybutynin Hydrochloride.

The combination of skin external preparation and transdermal patch is influenced by drug absorption through the skin. We investigated the effect of heparinoid cream on the transdermal absorption of oxybutynin hydrochloride using an oxybutynin transdermal patch and determined the combined effect of these medications. Normal skin and dry dorsal skin in hairless mice were treated with heparinoid cream, followed by the application of the oxybutynin transdermal patch. A blood sample was collected from the mouse tail vein and the blood concentration of oxybutynin hydrochloride was analyzed by LC-MS/MS. Transepidermal water loss, the hydration level of the stratum corneum, and the stratum corneum thickness in the dorsal skin were measured. The blood concentration and area under the curve (AUC)0→24 of oxybutynin hydrochloride increased when the 4.0-cm2 oxybutynin transdermal patch was applied 1 h after the application of the moisturizer, compared to the values without moisturizer. Normal skin and dry skin did not affect this result. As the hydration level of the stratum corneum and stratum corneum thickness increased before patch application by pre-treatment with moisturizer, it was suggested that transdermal absorption of oxybutynin hydrochloride was increased by skin hydration. The increased blood concentration of oxybutynin hydrochloride was regulated by changing the effective area of the patch and applying additional moisturizer at intervals. The pharmacokinetics of oxybutynin hydrochloride under the regulation of combination treatment was similar to that of treatment without moisturizer. These findings indicate that the application conditions of the oxybutynin transdermal patch and heparinoid cream influence the proper use of the patch.

In vitro and ex vivo approach for anti-urolithiatic potential of bioactive fractions of gokhru with simultaneous HPLC analysis of six major metabolites and their exploration in rat plasma.

CONTEXT: Tribulus terrestris L. (Zygophyllaceae) fruits have long been used in traditional systems of medicine for the treatment of various urinary diseases including urolithiasis. OBJECTIVE: To explore the anti-urolithiatic potential of gokhru and to develop an analytical method for quantitative estimation of metabolites for its quality control. MATERIALS AND METHODS: Aqueous extract of gokhru fruit was prepared through maceration followed by decoction to produce a mother extract, which was further used for polarity-based fractionations. In vitro and ex vivo anti-urolithiatic activity of mother extract and fractions at different concentration (100-1000 µg/mL) were carried out using aggregation assay in synthetic urine and in rat plasma, however, nucleation assay for 30 min was done using confocal microscopy. A simultaneous HPLC method has been developed for quantification of diosgenin, catechin, rutin, gallic acid, tannic acid and quercetin in mother extract and in fractions. RESULTS: The extraction resulted in 14.5% of w/w mother extract, however, polarity-based fractionation yielded 2.1, 2.6, 1.5, 1.3 and 6.1% w/w of hexane, toluene, dichloromethane (DCM), n-butanol and water fractions, respectively. In vitro and ex vivo studies showed a significant anti-urolithiatic potential of n-butanol fraction. Further, HPLC analysis revealed significantly (p < 0.01) higher content of quercetin (1.95 ± 0.41% w/w), diosgenin (12.75 ± 0.18% w/w) and tannic acid (9.81 ± 0.47% w/w) in n-butanol fraction as compared to others fractions. DISCUSSION AND CONCLUSION: In vitro and ex vivo studies demonstrated potent anti-urolithiatic activity of n-butanol fraction which can be developed as new phytopharmaceuticals for urolithiasis. HPLC method can be used for quality control and pharmacokinetic studies of gokhru.

Selective Spectrofluorimetric Method with Enhanced Sensitivity for Determination of Silodosine in Dosage Form and Human Plasma. Application to Stability Studies and Content Uniformity Testing.

A novel, sensitive and selective spectrofluorimetric method has been developed and validated for determination of silodosine (SLD) in its dosage form and human plasma. The method is based on nucleophilic substitution reaction of SLD with 5-(dimethylamino) naphthalene-1-sulfonyl chloride (dansyl chloride) in presence of 5.0 × 10-4 M sodium carbonate (pH 10.50) to yield a highly fluorescent derivative that was measured at 435 nm after excitation at 347 nm. The different experimental parameters affecting the development and stability of the reaction product were carefully studied and optimized. The fluorescence-concentration plot was rectilinear over the range 30.0-200.0 ng ml-1, with a correlation coefficient of 0.9979. The limits of detection (LOD) and quantification (LOQ) were found to be 5.44 and 16.47 ng ml-1, respectively. The proposed method was validated according to ICH guidelines, and successfully applied to the assay of commercial capsules as well as content uniformity testing. The high sensitivity of the proposed method allowed its successful application to the analysis of SLD in spiked human plasma with % recovery of 92.88 ± 1.05-100.73 ± 0.75%, (n = 6). The application of the proposed method was further extended to stability studies of SLD after exposure to different forced degradation conditions, such as acidic, alkaline and oxidative conditions, according to ICH guidelines, where this work describe the first attempt for selective spectrofluorimetric determination of silodosine in plasma and in the presence of its oxidative degradation.

A Case Report of Fatal Desmethyl Carbodenafil Toxicity.

We present the case report of a 34-year-old Hispanic male who was found unresponsive in the carport of his residence. Surveillance video footage from a security camera showed that he collapsed as he was walking to his vehicle. The decedent had no medical history and no history of illicit drug use. Initial toxicology testing revealed no alcohol or illicit drugs. Autopsy findings indicated a need for additional toxicological analysis due to a lack of trauma and the paucity of pathophysiologically significant natural disease. Liquid chromatography time-of-flight mass spectrometry of postmortem blood revealed the presence of two large peaks corresponding to desmethyl carbodenafil, an unapproved sildenafil analogue and its hydroxy metabolite. Species that are probable desmethyl and hydroxydesmethyl metabolites of desmethyl carbodenafil were also found. The mass and retention time of the parent compound in the decedent's sample were matched to those of a commercial standard. Based on this preliminary match, a method was developed and validated to quantify desmethyl carbodenafil in human blood. This is the first known case of fatal intoxication by desmethyl carbodenafil, a phosphodiesterase-5 inhibitor that is not approved for use in the United States. Over the past several years, retailers have issued voluntary recalls for dietary supplements marketed as sexual performance enhancers on the basis that these supplements may contain undeclared desmethyl carbodenafil.

Saliva versus Plasma Relative Bioavailability of Tolterodine in Humans: Validation of Class III Drugs of the Salivary Excretion Classification System.

Relative bioavailability study of tolterodine in healthy human volunteers was done using saliva and plasma matrices in order to investigate the robustness of using saliva instead of plasma as a surrogate for bioavailability and bioequivalence of class III drugs according to the salivary excretion classification system (SECS). Saliva and plasma samples were collected up to 16 h after 2 mg oral dose. Saliva and plasma pharmacokinetic parameters were calculated by non compartmental analysis using Kinetica program V5. Human effective intestinal permeability was optimized by SimCYP program V13. Tolterodine falls into class III (High permeability/Low fraction unbound to plasma proteins) and hence was subjected to salivary excretion. A high pearsons correlation coefficient of 0.97 between mean saliva and plasma concentrations, and saliva/plasma concentrations ratio of 0.33 were observed. In addition, correlation coefficients and saliva/plasma ratios of area under curve and maximum concentration were 0.98, 0.95 and 0.42, 0.34 respectively. On the other hand, time to reach maximum concentration was higher in saliva by 2.37 fold. In addition, inter subject variability values in saliva were slightly higher than plasma leading to need for slightly higher number of subjects to be used in saliva studies (55 vs. 48 subjects). Non-invasive saliva sampling instead of invasive plasma sampling method can be used as a surrogate for bioavailability and bioequivalence of SECS class I drugs when adequate sample size is used.

Optimisation of microstructured biodegradable finasteride formulation for depot parenteral application.

This study aimed to use the biocompatibility features of the biodegradable polymers to prepare depot injectable finasteride (FIN) microspheres for the treatment of benign prostatic hyperplasia. FIN microspheres were prepared utilising an emulsion-solvent evaporation/extraction technique. The Box-Behnken experimental design was adopted to optimise the preparation process. FIN plasma levels in albino rabbits were determined after injection with optimised FIN microspheres formula and compared with oral FIN suspension. Results revealed that the optimum microspheres displayed an amended sustained release pattern with lower initial burst. The cumulative FIN % released after 25 days was in the range 27.83-73.18% for F4 and F1, respectively. The optimised formula, with 50.0% (X1), and 22.316% (X2) and 1.38% (X3) showed 6.503 µm, 93.213%, 14.574%, and 64.838% for Y1, Y2, Y3, and Y4, respectively. In vivo studies displayed a sustained release pattern with minimal initial burst release when injected into rabbits.

Pharmacokinetic interaction of finasteride with tamsulosin hydrochloride: an open-label, randomized, 3-period crossover study in healthy Chinese male volunteers.

PURPOSE: The primary aim of this study was to evaluate whether there was clinically significant pharmacokinetic (PK) interaction between finasteride and tamsulosin in healthy Chinese male subjects. METHODS: This was an open-label, randomized, 3-period, crossover study. Subjects received single and multiple doses of 5 mg finasteride alone, single and multiple doses of 0.2 mg tamsulosin hydrochloride sustained-release capsule alone, and single and multiple doses of 5 mg finasteride with 0.2 mg tamsulosin hydrochloride, in an order determined by a computerized randomization schedule. Blood samples were collected up to 48 hours after dosing on study day 1 and up to 24 hours after dosing on study day 9 for determination of plasma concentrations with a validated LC-MS/MS method. Pharmacokinetic parameters were estimated via noncompartmental methods. Tolerability was evaluated by monitoring adverse events, laboratory assays, vital signs, and 12-lead ECG. FINDINGS: Fifteen subjects were enrolled, and 14 completed the study. The geometric mean ratios (GMRs) (90% CIs) of AUC(τ,ss) and C(max,ss) values of finasteride at steady state between coadministration of finasteride and tamsulosin hydrochloride and finasteride alone were 1.14 (1.05-1.23) and 1.06 (0.99-1.14), respectively. The GMRs (90% CIs) for AUC(0-t) and C(max) values of finasteride for a single dose of coadministration of finasteride and tamsulosin hydrochloride and finasteride alone were 1.02 (0.94-1.11) and 1.06 (1.01-1.11), respectively. The GMRs (90% CIs) for AUC(τ,ss) and C(max,ss) values of tamsulosin at steady-state for coadministration of finasteride and tamsulosin hydrochloride and tamsulosin hydrochloride alone were 1.18 (1.05-1.33) and 1.23 (1.06-1.43), respectively. The GMRs (90% CIs) for AUC(0-t) and C(max) values of tamsulosin for a single dose of coadministration of finasteride and tamsulosin hydrochloride and tamsulosin hydrochloride alone were 1.04 (0.97-1.10) and 1.04 (0.98-1.11), respectively. Statistical analyses confirmed that the 90% CIs for these PK parameters were within the predefined not clinically significant PK drug-drug interaction effect boundaries (0.5-2.0) in this study. If comparing the findings with narrower boundaries (0.8-1.25), the conclusion may not be supportive for tamsulosin hydrochloride. During the study, a total of 4 adverse events were reported in 3 subjects including allergic reaction, abnormal findings on an ECG, a slight increase in alanine aminotransferase, and a positive result on glucose urine test. IMPLICATIONS: Both finasteride and tamsulosin hydrochloride were well tolerated. Coadministration of finasteride and tamulosin hydrochloride seems unlikely to lead to a clinically significant PK drug-drug interaction, after a single dose and at steady state.

Improvement of trospium-specific absorption models for fasted and fed states in humans.

The purpose of this study was to mechanistically interpret the oral absorption pattern of trospium in fasted and fed states by means of gastrointestinal simulation technology. A drug absorption model was built on the basis of experimental data. According to the generated model, low permeability across the intestinal epithelium, delayed gastric emptying time and a prolonged residence time in the small intestine are the key factors governing trospium absorption in the fasted state. Furthermore, in silico modelling provided a plausible explanation of the pronounced reduction in the oral bioavailability of trospium when administered with food. The simulation results support the decreased dissolution in viscous medium, and the reduced drug permeability in the fed state as the predominant mechanisms for the food effect on trospium absorption.

Population pharmacokinetics of TC-5214, a nicotinic channel modulator, in phase I and II clinical studies.

TC-5214 (dexmecamylamine) is a nicotinic channel modulator that has previously been evaluated for treatment of major depression disorder (MDD) and is currently being evaluated by Targacept as a treatment for overactive bladder. A comprehensive population pharmacokinetic (POP PK) model of TC-5214 was developed using nonlinear mixed-effects modeling of pooled plasma concentration data from 6 early phase I studies in 179 healthy participants or patients with non-MDD and 1 phase II study in 68 MDD patients. Concentration-time profiles of TC-5214 after either single or multiple oral doses of TC-5214 was described by a one-compartment model with first-order absorption with lag time and first-order elimination. Covariate analysis revealed that creatinine clearance was a significant covariate on clearance and that body weight significantly influenced the central volume of distribution. The final model (with identified covariates) was used to simulate steady-state exposure for patients with impaired renal function. Results from forest plots reveal that patients with moderate to severe renal impairment or end stage renal disease are associated with significantly higher Cssmax and AUC compared to patients with normal renal function. The proposed final POP PK model could be employed in defining a TC-5214 dosage regimen in patients with impaired renal function.

Preparation and evaluation of once-daily sustained-release coated tablets of tolterodine-L-tartrate.

In this study, once-daily, sustained-release matrix tablets of tolterodine l-tartrate (TOL) for treatment of overactive bladder (OAB) were prepared by direct compression using various amounts of hydrophilic polymers such as HPMC 2910 and HPMC 2208 along with other tablet excipients; the tablets were then coated. In vitro dissolution studies were carried out under different pH conditions. The dissolution data were fitted into zero-order, first-order, Higuchi and Korsemeyer-Peppas models to identify the pharmacokinetics and mechanism of drug release. Among the four formulations (F1-F4), the dissolution profiles of formulation F2 were most similar to the marketed product with similarity and difference factors of 70.25 and 1.59 respectively. Furthermore, pharmacokinetic studies were carried out in healthy human volunteers after oral administration of the prepared TOL sustained-release matrix-coated tablet and the marketed product. The results revealed that the pharmacokinetic parameters of AUC, Cmax, Tmax, t1/2, Kel, and MRT of TOL for the developed formulation (F2) were not significantly different from that for the marketed product, suggesting that they were bioequivalent. Therefore, the developed sustained-release tablet formulation of TOL could be an alternative dosage form to the SR capsule for treatment of OAB.

Combining benefits of an adrenergic and a muscarinic blocker in a single formulation - a pharmacokinetic evaluation.

A pharmacokinetic bioequivalence study was conducted in Asian subjects, to compare a fixed dose combination capsule single oral dose of alpha adrenoceptor blocker-Alfuzosin hydrochloride 10mg extended release and muscarinic antagonists-Solifenacin succinate 5mg against individually administered Xatral XL 10mg tablets (Alfuzosin) of Sanofi Synthelabo Limited, United Kingdom (UK) and Vesicare 5mg tablets (Solifenacin) of Astellas Pharma Limited, UK under fed conditions. Blood samples were collected pre-dose up to 72 h post dose for determination of plasma Alfuzosin and Solifenacin concentrations and calculation of the pharmacokinetic parameters. ANOVA was performed on the log (natural)-transformed pharmacokinetic parameters. A 90% confidence interval for the ratios of the test and reference product averages (least square means) were calculated for alfuzosin and solifenacin. The 90% confidence intervals obtained for alfuzosin for Cmax, AUC0-t and AUC0-∞ were 102.74-122.75%, 95.84-116.96% and 95.82-116.76%, respectively. The 90% confidence intervals obtained for Solifenacin for Cmax, and AUC0-72 were 89.55-97.91% and 90.47-99.38%, respectively. Based on the results, the fixed dose combination was concluded to be bioequivalent to individually administered products.

Synergistic effect of iontophoresis and chemical enhancers on transdermal permeation of tolterodine tartrate for the treatment of overactive bladder.

PURPOSE: The objective of the study was to evaluate the synergistic transdermal permeation effect of chemical enhancers and iontophoresis technique on tolterodine tartrate (TT) transdermal gel and to evaluate its pharmacokinetic properties. MATERIALS AND METHODS: Taguchi robust design was used for optimization of formulations. Skin permeation rates were evaluated using the Keshary-chein type diffusion cells in order to optimize the gel formulation. In-vivo studies of the optimized formulation were performed in a rabbit model and histopathology studies of optimized formulation were performed on rats. RESULTS: Transdermal gels were formulated successfully using Taguchi robust design method. The type of penetration enhancer, concentration of penetration enhancer, current density and pulse on/off ratio were chosen as independent variables. Type of penetration enhancer was found to be the significant factor for all the responses. Permeation parameters were evaluated when maximum cumulative amount permeated in 24 hours (Q24) was 145.71 ± 2.00µg/cm² by CIT4 formulation over control (91.89 ± 2.30µg/cm²). Permeation was enhanced by 1.75 fold by CIT4 formulation. Formulation CIT4 containing nerolidol (5%) and iontophoretic variables applied (0.5mA/cm² and pulse on/off ratio 3:1) was optimized. In vivo studies with optimized formulation CIT4 showed increase in AUC and T1/2 when compared to oral suspension in rabbits. The histological studies showed changes in dermis indicating the effect of penetration enhancers and as iontophoresis was continued only for two cycles in periodic fashion so it did not cause any skin damage observed in the slides. CONCLUSION: Results indicated that iontophoresis in combination with chemical enhancers is an effective method for transdermal administration of TT in the treatment of overactive bladder.

Synergistic effect of iontophoresis and chemical enhancers on transdermal permeation of tolterodine tartrate for the treatment of overactive bladder

Purpose The objective of the study was to evaluate the synergistic transdermal permeation effect of chemical enhancers and iontophoresis technique on tolterodine tartrate (TT) transdermal gel and to evaluate its pharmacokinetic properties. Materials and Methods Taguchi robust design was used for optimization of formulations. Skin permeation rates were evaluated using the Keshary-chein type diffusion cells in order to optimize the gel formulation. In-vivo studies of the optimized formulation were performed in a rabbit model and histopathology studies of optimized formulation were performed on rats. Results Transdermal gels were formulated successfully using Taguchi robust design method. The type of penetration enhancer, concentration of penetration enhancer, current density and pulse on/off ratio were chosen as independent variables. Type of penetration enhancer was found to be the significant factor for all the responses. Permeation parameters were evaluated when maximum cumulative amount permeated in 24 hours (Q24) was 145.71 ± 2.00µg/cm2 by CIT4 formulation over control (91.89 ± 2.30µg/cm2). Permeation was enhanced by 1.75 fold by CIT4 formulation. Formulation CIT4 containing nerolidol (5%) and iontophoretic variables applied (0.5mA/cm2 and pulse on/off ratio 3:1) was optimized. In vivo studies with optimized formulation CIT4 showed increase in AUC and T1/2 when compared to oral suspension in rabbits. The histological studies showed changes in dermis indicating the effect of penetration enhancers and as iontophoresis was continued only for two cycles in periodic fashion so it did not cause any skin damage observed in the slides. Conclusion Results indicated that iontophoresis in combination with chemical enhancers is an effective method for transdermal administration of TT in the treatment of overactive bladder. .

A formulation approach for development of HPMC-based sustained release tablets for tolterodine tartrate with a low release variation.

OBJECTIVE: The purpose of this study was to develop hydroxypropylmethylcellulose (HPMC)-based sustained release (SR) tablets for tolterodine tartrate with a low drug release variation. METHODS: The SR tablets were prepared by formulating a combination of different grades of HPMC as the gelling agents. The comparative dissolution study for the HPMC-based SR tablet as a test and Detrusitol SR capsule as a reference was carried out, and the bioequivalence study of the two products was also conducted in human volunteers. RESULTS: The amount of HPMC, the grade of HPMC and the combination ratio of different grades of HPMC had remarkable effects on drug release from the SR tablets. Both the test and reference products had no significant difference in terms of comparative dissolution patterns in four different media (f2 > 50). Furthermore, the dissolution method and rotation speed showed no effects on the drug release from the two products. The 90% confidence intervals of the AUC(0-36) and C(max) ratios for the test and reference products were within the acceptable bioequivalence intervals of log0.8-log1.25. CONCLUSIONS: A HPMC-based SR tablet for tolterodine tartrate with a low release variation was successfully developed, which was bioequivalent to Detrusitol® SR capsule.