A nano-level assay of tizanidine using the fluorogenic character of benzofurazan derivative: Application to plasma, tablets, and content homogeneity evaluation.

People frequently administer Tizanidine (TIZ) to treat spasticity resulting from diseases like multiple sclerosis or spinal cord injuries. It also helps prevent muscle spasms. It helps to relax and release tense and stiff muscles by inhibiting specific nerve signals in the brain and spinal cord. The technique employed in this study made use of the unique ability of benzofurazan to confer fluorescent character when reacted with TIZ at specific conditions. This fluorogenic property was harnessed to evolve a remarkably sensitive, affordable, and selective method to quantify TIZ. The resulting yellow fluorescent product was observedat a wavelength beam of 532.9 nm, and an excitation wavelength beam of 474.9 nm was applied. By looking at the response across the TIZ concentration, the calibration chart's linearity was assessed in the range of 40-500 ng/mL. By computation, the approach's detection level (LOD) was determined to be 11.9 ng/mL, while the quantitation level was approximated to be 36 ng/mL. All pertinent factors impacting the strategy's efficacy were thoroughly inspected and adjusted accordingly. The proposed strategy was validated following the guidelines outlined by the ICH. The outcomes confirmed the method's capability for the accurate quantifying of TIZ in tablets, spiked plasma, and pharmaceutical assessing content uniformity.

Recommended dosages of analgesic and sedative drugs in intensive care result in a low incidence of potentially toxic blood concentrations.

Background: Standard dosages of analgesic and sedative drugs are given to intensive care patients. The resulting range of blood concentrations and corresponding clinical responses need to be better examined. The purpose of this study was to describe daily dosages, measured blood concentrations, and clinical responses in critically ill patients. The purpose was also to contribute to establishing whole blood concentration reference values of the drugs investigated. Methods: A descriptive study of prospectively collected data from 302 admissions to a general intensive care unit (ICU) at a university hospital. Ten drugs (clonidine, fentanyl, morphine, dexmedetomidine, ketamine, ketobemidone, midazolam, paracetamol, propofol, and thiopental) were investigated, and daily dosages recorded. Blood samples were collected twice daily, and drug concentrations were measured. Clinical responses were registered using Richmond agitation-sedation scale (RASS) and Numeric rating scale (NRS). Results: Drug dosages were within recommended dose ranges. Blood concentrations for all 10 drugs showed a wide variation within the cohort, but only 3% were above therapeutic interval where clonidine (57 of 122) and midazolam (38 of 122) dominated. RASS and NRS were not correlated to drug concentrations. Conclusion: Using recommended dose intervals for analgesic and sedative drugs in the ICU setting combined with regular monitoring of clinical responses such as RASS and NRS leads to 97% of concentrations being below the upper limit in the therapeutic interval. This study contributes to whole blood drug concentration reference values regarding these 10 drugs.

Effect of Vemurafenib on the Pharmacokinetics of a Single Dose of Tizanidine (a CYP1A2 Substrate) in Patients With BRAFV600 Mutation-Positive Malignancies.

This phase 1 open-label, multicenter, 3-period, fixed-sequence study evaluated the effect of multiple doses of vemurafenib on the pharmacokinetics of 1 dose of tizanidine, a probe CYP1A2 substrate, in patients with BRAFV600 mutation-positive metastatic malignancy. Patients received 1 dose of tizanidine 2 mg on day 1 (period A), vemurafenib 960 mg twice daily on days 2-21 (period B), and 1 dose of tizanidine 2 mg and vemurafenib 960 mg twice daily on day 22 (period C). Log-transformed area under the concentration-time curve (AUC) and maximum plasma concentration (Cmax ) values for tizanidine in 16 patients were compared between periods A (tizanidine alone) and C (tizanidine plus vemurafenib) using an analysis of variance model. Multiple doses of vemurafenib increased plasma exposure of 1 dose of tizanidine, with geometric mean ratios (period C/period A) for Cmax , AUCinf , and AUClast of 2.15 (90%CI, 1.71-2.71), 4.22 (90%CI, 3.37-5.28), and 4.74 (90%CI, 3.55-6.33), respectively; 90%CIs were all outside predefined limits for lack of drug-drug interaction (0.82-1.22). This study confirmed vemurafenib as a moderate inhibitor of CYP1A2 in vivo, with a statistically significant drug-drug interaction with tizanidine. Caution should be exercised when dosing vemurafenib concurrently with CYP1A2 substrates.

Effect of lofexidine on cardiac repolarization during treatment of opioid withdrawal.

BACKGROUND: Lofexidine is a non-opioid treatment for opioid withdrawal syndrome. Its sympatholytic actions counteract the nor-adrenergic hyperactivity that occurs during abrupt opioid withdrawal. METHODS: The effect of lofexidine 2.16 and 2.88 mg/day on QTcF (QT interval, heart-rate corrected, Fridericia formula) was studied as part of a large, double-blind, placebo-controlled trial (ClinicalTrials.gov identifier: NCT01863186). ECGs were time-matched to blood sampling for lofexidine concentration and were collected at prespecified timepoints over a 7-day inpatient period. Analyses included mean change-from-baseline QTcF and exposure-response modeling to predict QTcF at relevant lofexidine concentrations. RESULTS: A total of 681 adult men and women received at least 1 dose of study drug; 566 qualified for inclusion in the concentration-QTcF analysis. Most subjects were withdrawing from heroin. During the first 24 h (Days 1-2) post-baseline, small increases in QTcF were observed in all groups: 4.7 ms for lofexidine 2.16 mg, 7.4 ms for lofexidine 2.88 mg and 1.4 ms for placebo. These increases were transient; by Day 4, when lofexidine levels had reached steady-state, QTcF increases were not present. By Day 7, QTcF was decreased from baseline in all groups. Exposure-response modeling predicted <10 ms increases in QTcF at lofexidine concentrations 3 times those obtained at maximal recommended dose. CONCLUSIONS: Lofexidine was associated with small, transient QTcF increases. Decreases in QTcF that occurred with higher lofexidine concentrations argue for an indirect QTcF effect, potentially from changes in autonomic tone. Both opioid withdrawal and lofexidine's sympatholytic actions would be expected to alter sympathetic outflow over the 7-day withdrawal.

Optimizing clonidine dosage for sedation in mechanically ventilated children: A pharmacokinetic simulation study.

BACKGROUND: Clonidine is in widespread off-label use as a sedative in mechanically ventilated children, despite limited evidence of efficacy. A variety of dosage regimens have been utilized in clinical practice and in research studies. Within these studies, clonidine has inconsistently shown useful sedation properties. One of the reasons attributed to the inconsistent signs of efficacy is suboptimal clonidine dosing. AIMS: This study aims to propose a target plasma concentration and simulate clonidine pharmacokinetics (PK) in a cohort of mechanically ventilated children to evaluate the adequacy of clonidine dosage regimens used in clinical practice and research studies. METHODS: A literature search was undertaken to identify a clonidine pharmaockinetic-pharmacodynamics (PKPD) model, from which a target concentration for sedation was defined. Using a previously published PK model, the projected plasma concentrations of 692 mechanically ventilated children (demographics taken from a recent study) were generated. Doses from recently published clinical studies were investigated. Adequacy of each regimen to attain therapeutic clonidine plasma concentrations was assessed. RESULTS: A target plasma concentration of above 2 µg/L was proposed. Nine dosage regimens (four intravenous boluses, four intravenous infusions, and one nasogastric route boluses) were evaluated ranging from 1 µg/kg eight hourly intravenous boluses to a regimen up to 3 µg/kg/hr continuous intravenous infusion. Regimens with a loading dose of 2 µg/kg followed by variable continuous infusion of up to 2 µg/kg/hr titrated according to sedation score appear most suitable. Doses should be halved in neonates. CONCLUSION: The variety of dosage regimens in the previous studies of clonidine along with difficulties in the conduct of interventional studies may have contributed to the lack of efficacy data to support its use. Simulations of clonidine plasma concentrations based on known population pharmacokinetic parameters suggest a loading dose followed by higher than current practice maintenance dose infusion is required to achieve adequate steady-state concentrations early in treatment. Further PKPD studies will aid in the determination of the optimal clonidine dosage regimen.

Development of thiomer based buccal films for the enhancement of bioavailability: An in-vivo analysis.

Present work was conducted to improve the bioavailability of Tizanidine HCl (TZN) by formulating mucoadhesive buccal films (MBFs) using novel thiolated arabinoxylan (TAX) as film former. MBF's were prepared by solvent casting technique followed by their evaluation for surface morphology and folding endurance. Moreover, pharmacokinetic parameters including Cmax, tmax, t1/2 and AUC were determined after administering standard oral solution (SOS) and MBFs of TZN at a dose of 1mg/kg. Successful thiolation was confirmed by the presence of 4.98 to 7.04 mmol of thiol content per gram of the polymer. Results of in-vivo pharmacokinetics have signified (p=0.0089) the suitability of MBFs as a carrier of drug through buccal route. Results have explored that, t1/2 was increased from 2.51hrs (SOS) to 10 hrs, Cmax from 42.3 ng/ml (SOS) to 105ng/ml and tmax from 2hrs (SOS) to 6h. Conclusively, TAX has exhibited the potential to form MBFs thereby offering sustained release of TZN with improved pharmacokinetic profile.

Validation of a HPLC/MS method for simultaneous quantification of clonidine, morphine and its metabolites in human plasma.

A high-performance liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous quantification of morphine, morphine's major metabolites morphine-3-glucuronide and morphine-6-glucuronide, and clonidine, to support the pharmacokinetic analysis of an ongoing double-blinded randomized clinical trial that compares the use of morphine and clonidine in infants diagnosed with neonatal abstinence syndrome. Plasma samples were processed by solid-phase extraction and separated on an Inertsil ODS-3 (4 µm) column using an 0.1% formic acid in water-0.1% formic acid in methanol gradient. Detection of the analytes was conducted in the positive multiple reaction monitoring mode. The range of quantitation was 1-1000 ng/mL for morphine, morphine-3-glucuronide and morphine-6-glucuronide, and 0.25-100 ng/mL for clonidine. Intra-day and inter-day accuracy and precision were ≤15% for all analytes across the quantitation range. Extraction recovery rates were ≥94% for morphine, ≥90% for M3G, ≥87% for M6G and ≥ 79% for clonidine. Matrix effect ranged from 85-94% for clonidine to 101-106% for M3G. The method fulfilled all predetermined acceptance criteria and required only 100 µL of starting plasma volume. Furthermore, it was successfully applied to 30 clinical trial plasma samples.

Prospective study of relevance of 123I-MIBG myocardial scintigraphy and clonidine GH test to distinguish Parkinson's disease and multiple system atrophy.

BACKGROUND: 123I-MIBG myocardial scintigraphy and clonidine growth hormone test (CGH test) may help to distinguish multiple system atrophy (MSA) from Parkinson's disease (PD). Their relevance in the first-stage parkinsonism of uncertain etiology is unknown. METHODS: Patients experiencing parkinsonism of ambiguous etiology were clinically classified into the PD group or the MSA group as initial clinical diagnosis (ICD). Then, CGH test and myocardial scintigraphy were performed. Clinical assessment was repeated throughout the disease course until the final clinical diagnosis (FCD) could be established according to the criteria of PD and MSA, respectively. RESULTS: Twenty-five patients with uncertain diagnosis were included (15 MSA and 10 PD as ICD). At the end of a 6-year follow-up, FCD was MSA in 11/25 patients and PD in 14/25. The CGH test and the scintigraphy showed a sensitivity of 82%, and a specificity of 71 and 93%, respectively, for the diagnosis of MSA. The combination of a normal scintigraphy (i.e., with myocardial MIBG uptake) with genitourinary dysfunction was the most relevant test to diagnose MSA, whereas an abnormal scintigraphy with a levodopa response of > 30% or an abnormal scintigraphy with the absence of OH was the most relevant combinations to diagnose PD. All these combinations had an accuracy superior than 90% and a specificity of 100%. CONCLUSION: Combinations of myocardial scintigraphy with genitourinary dysfunction, levodopa response of > 30%, or orthostatic hypotension could be of interest for the distinction between PD and MSA when the clinical diagnosis remains ambiguous at the first stage of the disease.

The use of clonidine in elderly patients with delirium; pharmacokinetics and hemodynamic responses.

BACKGROUND: The Oslo Study of Clonidine in Elderly Patients with Delirium (LUCID) is an RCT investigating the effect of clonidine in medical patients > 65 years with delirium. To assess the dosage regimen and safety measures of this study protocol, we measured the plasma concentrations and hemodynamic effects of clonidine in the first 20 patients. METHODS: Patients were randomised to clonidine (n = 10) or placebo (n = 10). The treatment group was given a loading dose (75µg every 3rd hour up to a maximum of 4 doses) to reach steady state, and further 75µg twice daily until delirium free for 2 days, discharge or a maximum of 7 days. Blood pressure (BP) and heart rate (HR) were measured just before every dose. If the systolic BP was < 100 mmHg or HR < 50 beats per minute the next dose was omitted. Plasma concentrations of clonidine were measured 3 h after each drug intake on day 1, just before intake (day 2 and at steady state day 4-6) and 3 h after intake at steady state (Cmax). Our estimated pre-specified plasma concentration target range was 0.3-0.7µg/L. RESULTS: 3 h after the first dose of 75µg clonidine, plasma concentration levels rose to median 0.35 (range 0.24-0.40)µg/L. Median trough concentration (C0) at day 2 was 0.70 (0.47-0.96)µg/L. At steady state, median C0 was 0.47 (0.36-0.76)µg/L, rising to Cmax 0.74 (0.56-0.95)µg/L 3 h post dose. A significant haemodynamic change from baseline was only found at a few time-points during the loading doses within the clonidine group. There was however extensive individual BP and HR variation in both the clonidine and placebo groups, and when comparing the change scores (delta values) between the clonidine and the placebo groups, there were no significant differences. CONCLUSIONS: The plasma concentration of clonidine was at the higher end of the estimated therapeutic range. Hemodynamic changes during clonidine treatment were as expected, with trends towards lower blood pressure and heart rate in patients treated with clonidine, but with dose adjustments based on SBP this protocol appears safe. TRIAL REGISTRATION: ClinicalTrials.gov NCT01956604 , 09.25.2013. EudraCT Number: 2013-000815-26, 03.18.2013. Enrolment of first participant: 04.24.2014.

Quantitative analysis of clonidine and ephedrine by a microfluidic system: On-chip electromembrane extraction followed by high performance liquid chromatography.

In this work, a microfluidic device was developed for on-chip electromembrane extraction of trace amounts of ephedrine (EPH) and clonidine (CLO) in human urine and plasma samples followed by HPLC-UV analysis. Two polymethylmethacrylate plates were used as substrates and a microchannel was carved in each plate. The microchannel channel on the underneath plate provided the flow pass of the sample solution and the one on the upper plate dedicated to a compartment for the stagnant acceptor phase. A piece of polypropylene sheet was impregnated by an organic solvent and mounted between the two parts of the chip device. An electrical field, across the porous sheet, was created by two embedded platinum electrodes placed in the bottom of the channels which were connected to a power supply. The analytes were converted to their ionized form, passed through the supported liquid membrane, and then extracted into the acceptor phase by the applied voltage. All the effective parameters including the type of the SLM, the SLM composition, pH of donor and acceptor phases, and the quantity of the applied voltage were evaluated and optimized. Several organic solvents were evaluated as the SLM to assess the effect of SLM composition. Other parameters were optimized by a central composite design. Under the optimal conditions of voltage of 74V, flow rate of 28µLmin-1, 100 and 20mM HCl as acceptor and donor phase composition, respectively, the calibration curves were plotted for both analytes. The limits of detection were less than 7.0 and 11µgL-1 in urine and plasma, respectively. The linear dynamic ranges were within the range of 10-450 and 25-500µgL-1 (r2˃0.9969) for CLO, and within the range of 20-450 and 30-500µgL-1 (r2˃0.9907) for EPH in urine and plasma, respectively. To examine the capability of the method, real biological samples were analyzed. The results represented a high accuracy in the quantitative analysis of the analytes with relative recoveries within the range of 94.6-105.2% and acceptable repeatability with relative standard deviations lower than 5.1%.

A highly sensitive method for the simultaneous UHPLC-MS/MS analysis of clonidine, morphine, midazolam and their metabolites in blood plasma using HFIP as the eluent additive.

In intensive care units, the precise administration of sedatives and analgesics is crucial in order to avoid under- or over sedation and for appropriate pain control. Both can be harmful to the patient, causing side effects or pain and suffering. This is especially important in the case of pediatric patients, and dose-response relationships require studies using pharmacokinetic-pharmacodynamic modeling. The aim of this work was to develop and validate a rapid ultra-high performance liquid chromatographic-tandem mass spectrometric method for the analysis of three common sedative and analgesic agents: morphine, clonidine and midazolam, and their metabolites (morphine-3-glucuronide, morphine-6-glucuronide and 1'-hydroxymidazolam) in blood plasma at trace level concentrations. Low concentrations and low sampling volumes may be expected in pediatric patients; we report the lowest limit of quantification for all analytes as 0.05ng/mL using only 100µL of blood plasma. The analytes were separated chromatographically using the C18 column with the weak ion-pairing additive 1,1,1,3,3,3-hexafluoro-2-propanol and methanol. The method was fully validated and a matrix matched calibration range of 0.05-250ng/mL was attained for all analytes In addition, between-day accuracy for all analytes remained within 93-108%, and precision remained within 1.5-9.6% for all analytes at all concentration levels over the calibration range.

Effects of low-dose clonidine on cardiovascular and autonomic variables in adolescents with chronic fatigue: a randomized controlled trial.

BACKGROUND: Chronic Fatigue Syndrome (CFS) is a common and disabling condition in adolescence with few treatment options. A central feature of CFS is orthostatic intolerance and abnormal autonomic cardiovascular control characterized by sympathetic predominance. We hypothesized that symptoms as well as the underlying pathophysiology might improve by treatment with the alpha2A-adrenoceptor agonist clonidine. METHODS: A total of 176 adolescent CFS patients (12-18 years) were assessed for eligibility at a single referral center recruiting nation-wide. Patients were randomized 1:1 by a computer system and started treatment with clonidine capsules (25 µg or 50 µg twice daily, respectively, for body weight below/above 35 kg) or placebo capsules for 9 weeks. Double-blinding was provided. Data were collected from March 2010 until October 2012 as part of The Norwegian Study of Chronic Fatigue Syndrome in Adolescents: Pathophysiology and Intervention Trial (NorCAPITAL). Effect of clonidine intervention was assessed by general linear models in intention-to-treat analyses, including baseline values as covariates in the model. RESULTS: A total of 120 patients (clonidine group n = 60, placebo group n = 60) were enrolled and started treatment. There were 14 drop-outs (5 in the clonidine group, 9 in the placebo group) during the intervention period. At 8 weeks, the clonidine group had lower plasma norepinephrine (difference = 205 pmol/L, p = 0.05) and urine norepinephrine/creatinine ratio (difference = 3.9 nmol/mmol, p = 0.002). During supine rest, the clonidine group had higher heart rate variability in the low-frequency range (LF-HRV, absolute units) (ratio = 1.4, p = 0.007) as well as higher standard deviation of all RR-intervals (SDNN) (difference = 12.0 ms, p = 0.05); during 20° head-up tilt there were no statistical differences in any cardiovascular variable. Symptoms of orthostatic intolerance did not change during the intervention period. CONCLUSIONS: Low-dose clonidine reduces catecholamine levels in adolescent CFS, but the effects on autonomic cardiovascular control are sparse. Clonidine does not improve symptoms of orthostatic intolerance. TRIAL REGISTRATION: Clinical Trials ID: NCT01040429, date of registration 12/28/2009.

Validation of a HPLC-ESI MS/MS method for the determination of clonidine in human plasma and its application in a bioequivalence study in Chinese healthy volunteers.

A rapid and sensitive liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method to determine clonidine in human plasma was developed and fully validated. Sample preparation was involved an one-step extraction with diethyl ether. Donepezil was employed as the internal standard (IS). Chromatographic separation was performed on a Hypersil BDS C18 column (i.d. 2.1 × 50 mm, particle size 3µm) with a mobile phase of methanol-water (containing 0.1% formic acid; 60:40, v/v) at a flow rate of 200 µL/min. The peaks were detected by mass spectrometry using the electrospray ion source in selected reaction monitoring mode. The extraction recovery was 72.53-85.25%. The method was found to be linear in a concentration range of 0.02-6.00 ng/mL and the lower limit of quantification was 0.02 ng/mL. The within- and between-batch precisions at three concentrations were 4.33-16.47 and 7.24-17.24% with accuracies of -2.47-10.91 and 1.86-10.19%, respectively. This validated method was successfully used for a bioequivalence study of two clonidine transdermal patches on healthy volunteers. The results suggested that the test formulation of clonidine patch met the regulatory criterion for bioequivalence to the reference formulation, but a larger sample size should be needed for the estimation of bioequivalence.

Development of an LC-MS/MS method for determining the pharmacokinetics of clonidine following oral administration of Zhenju antihypertensive compound.

Zhenju antihypertensive compound (ZJAHC) is a combined Chinese-Western medicine formula including clonidine (CLO), hydrochlorothiazide (HCT), rutin, Chrysanthemum indicum extract and pearl powder. Compared with CLO preparations, ZJAHC shows improved activities and decreased adverse effects. It is believed that the side effects of CLO are caused by its high peak plasma concentration. Hence, study of the influence of ZJAHC on the pharmacokinetic behaviors of clonidine seems essential. In present study, the plasma concentrations of CLO were determined with a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. The MS/MS transitions monitored for clonidine and internal standard were 230.2 → 213.1 and 152.2 → 110.2, respectively. The analyte was quantified in a single run within 3 min. The pharmacokinetic study showed that the area under the plasma concentration-time curve of CLO in ZJAHC (60 µg/kg CLO) was similar to that of CLO-HCT-high (120 µg/kg CLO) but the peak concentration was much lower than that in CLO-HCT-high. ZJAHC could enhance the bioavailability without greatly increasing peak concentration of clonidine. This comprehensive effect of enhancing the bioavailability and avoiding the high peak plasma concentration for CLO might mainly result from the co-contribution of Western medicine and traditional Chinese medicine (TCM), while the effect of TCM was stronger than that of Western medicine.

Enteral absorption and haemodynamic response of clonidine in infants post-cardiac surgery.

BACKGROUND: Clonidine is a useful analgesic-sedative agent; however, few data exist regarding its use in infants after congenital heart disease surgery. We thus aimed to assess the absorption and safety of enterally administered clonidine in this setting. METHODS: Sixteen infants (median age 6.7 months) received a single nasogastric dose of 3 µg kg(-1) clonidine 2-6 h after surgery. Blood samples were obtained at seven time intervals (up to 480 min). Plasma concentration profiles were obtained, and then pooled with a previous study (137 samples, 30 infants) for estimation of population pharmacokinetic parameters (NONMEM version 7.2). RESULTS: Enteral absorption showed considerable inter-individual variability, with clonidine Cmax ranging from 0.15 to 1.55 ng ml(-1) (median 0.73), and Tmax from 12 to 478 min (median 190). Although therapeutic sedative plasma concentrations were achieved in 94% of patients, only half had attained this by 70 min post-dose. Patients who did not receive inotropes exhibited a positive association between cumulative morphine dose and Tmax (interaction effect P=0.03); this was not seen among those receiving inotropes. The haemodynamic profile was favourable; few patients required fluid boluses, and this bore no relationship to plasma clonidine concentration. Population pharmacokinetic parameter estimation yielded results similar to previous paediatric studies: clearance 13.7 litre h(-1) 70 kg(-1) and Vd 181 litre 70 kg(-1). CONCLUSIONS: Early postoperative enteral clonidine produces favourable haemodynamic profiles and therapeutic plasma concentrations in the majority of cardiac surgical infants; however, the time to achieve this can be erratic. Thus, parenteral administration may be preferable if rapid analgo-sedative effects are needed.

Rapid simultaneous determination of eperisone, tolperisone, and tizanidine in human serum by using a MonoSpin® C18 extraction column and liquid chromatography/tandem mass spectrometry.

A method was developed for rapid toxicological analysis of eperisone, tolperisone, and tizanidine in human serum using a MonoSpin® C18 extraction column and LC/MS/MS. The method was validated for LOD, linearity, precision, and extraction recovery. This method was rapid with an LOD of 0.5 ng/mL, linearity range 1-500.0 ng/mL (r2 = 0.999), and RSD value below 14.6%. Extraction recovery from the sample was greater than 98.6, 98.8, and 88.5% for eperisone, tolperisone, and tizanidine, respectively. Results showed that combination of the MonoSpin C18 extraction column and LC/MS/MS is a simple and rapid method for the analysis of these three analytes, and a method is described for simultaneous quantitative determination of the analytes in human serum by LC/MSIMS. This method was used to determine the serum levels of eperisone in a patient with eperisone poisoning, and could be successfully applied for screening analyses in clinical cases other than poisoning.

Dermal exposure to a compounded pain cream resulting in severely elevated clonidine concentration.

INTRODUCTION: Clonidine is an imidazoline derivative antihypertensive medication that is also used as adjunctive therapy for neuropathic pain disorders via topical administration. Clonidine overdose can manifest both central and peripheral alpha-adrenergic agonist effects. CASE REPORT: A 23-year-old man presented to an emergency department with altered mental status, bradycardia, and hypertension after suspected overdose. He had rubbed a specially compounded medicinal cream over his entire body containing clonidine 0.2 % (w/w), gabapentin 6 %, imipramine 3 %, ketamine 10 %, lidocaine 2 %, and mefenamic acid 1 %. The patient presented with severe hypertension, bradycardia, and altered mental status. He was found to have a subarachnoid hemorrhage and was treated for hypertensive emergency. Toxicological analysis of initial blood samples revealed a serum clonidine concentration of 5,200 ng/ml. At 6-month follow-up, the patient had made a full recovery. DISCUSSION: There are limited reports of topical clonidine toxicity, and to our knowledge, this case involves the highest concentration yet reported following clonidine overdose by any route of exposure. The severely elevated serum clonidine concentration found in our patient demonstrates the possibility of toxicity resulting from inappropriate use of such a product. At high serum concentrations, the pharmacodynamic effects of clonidine appear to cause significant peripheral alpha-1 adrenergic stimulation. Toxicologists should be aware of the increasing use of topical clonidine preparations for the treatment of neuropathic pain and the potential for toxicity.

Compounded ointment results in severe toxicity in a pediatric patient.

BACKGROUND: Dermal drug delivery is becoming more common, as evidenced by the increased numbers of compounding pharmacies preparing topical products for chronic pain management. Consumers may not appreciate the potency or dangers associated with some of the drugs in these preparations. Pediatric patients are especially at risk for significant toxicity with accidental exposures. We report a case of severe toxicity in an 18-month-old boy from exposure to his father's compounded pain ointment. CASE: An 18-month-old previously healthy child had an ointment applied topically to a diaper rash by his mother, consisting of a single pump of a prescription ointment that her husband received from a compounding pharmacy for neck pain. Approximately 20 minutes later, when the child had been put down for a nap, he had gasping respiration but was otherwise unresponsive. Emergency medical services was called, and the child was unresponsive. In the ED, vital signs were pulse of 57 beats/min, blood pressure 74/35 mm Hg, respiratory rate 21 breaths/min, and O2 saturation 98% on a nonrebreather. Fingerstick glucose was 105 mg/dL. In the ED, physical examination was significant for unresponsiveness, pinpoint pupils, and hyporeflexia. The patient's mental status continued to deteriorate with depressed respirations, and he was intubated. Laboratory results were noncontributory. Electrocardiogram revealed only sinus bradycardia. The patient was transported to a pediatric intensive care unit. He did well over the next several hours with supportive care and had return to normal vital signs over the following 12 hours. He was extubated the following morning without problems. Blood taken at the time of ED presentation had a serum clonidine level of 9.2 ng/mL (reference range, 0.5-4.5 ng/mL) and a norketamine level of 41 ng/mL (reporting limit, >20 ng/mL). CONCLUSIONS: Dermal absorption of drugs leading to significant toxicity in children is well known. Our patient had toxicity from a topical pain medication compounded with several potent drugs known to cause central nervous system depression. There has been an increase in the use of this drug delivery system for management of chronic painful conditions. The popularity and attractiveness of such preparations may be the perception that they are somehow safer and more natural than taking pills. This perception and the fact that these are not dispensed in child-proof containers and are often mailed to the patients without pharmacist counseling can lead to increased inadvertent exposures in the pediatric population.

Sensitive spectrofluorimetric determination of tizanidine in pharmaceutical preparations, human plasma and urine through derivatization with dansyl chloride.

A sensitive spectrofluorimetric method was developed for the determination of tizanidine in human plasma, urine and pharmaceutical preparations. The method is based on reaction of tizanidine with 1-dimethylaminonaphthalene-5-sulphonyl chloride (dansyl chloride) in an alkaline medium to form a highly fluorescent derivative that was measured at 511 nm after excitation at 383 nm. The different experimental parameters affecting the fluorescence intensity of tizanidine was carefully studied and optimized. The fluorescence-concentration plots were rectilinear over the ranges 50-500 and 20-300 ng/mL for plasma and urine, respectively, detection limits of 1.81 and 0.54 ng/mL and quantification limits of 5.43 and 1.62 ng/mL for plasma and urine, respectively. The method presents good performance in terms of linearity, detection and quantification limits, precision, accuracy and specificity. The proposed method was successfully applied for the determination of tizanidine in pharmaceutical preparations. The results obtained were compared with a reference method, using t- and F-tests.

LC-MS/MS sensitivity enhancement using 2D-SCX/RPLC and its application in the assessment of pharmacokinetics of clonidine in dried blood spots.

BACKGROUND: Dried blood spot (DBS) technology offers distinctive preclinical and clinical advantages primarily ascribed to microscale sampling (e.g., 40-80 µl per time point), and the nature of solid-state samples in filter papers. Logistic benefits in sample collection, storage and shipping also result. However, the effective DBS samples available for bioanalysis are finite, that is, in the order of approximately 1 µl equivalent of plasma (3-mm punch) from a DBS of approximately 15-20 µl whole blood samples. This represents 20- to 100-times fewer samples for bioanalysis compared with a typical plasma assay. It is critical to increase LC-MS/MS sensitivity to accommodate DBS bioanalysis. RESULTS: We developed a 2D strong cation exchange reversed-phase LC-MS/MS (2D-SCX/RPLC-MS/MS) for online enrichment, separation and detection of basic polar compounds, using clonidine hydrochloride as a model compound. Positively charged clonidine was retained and enriched in the first dimensional SCX column even in large volumes, eluted to a second dimensional RP column with ammonium acetate, de-salted with highly aqueous solvent and separated in an analytical RP column. Injection of 100 µl clonidine extract exhibited essentially the same peak shape as that from 1 µl and the response of clonidine increased quantitatively in the range of 1-100 µl. CONCLUSION: The method was successfully employed to analyze clonidine DBS samples from an in-house toxicology study, where clonidine hydrochloride was administered to cynomolgus monkeys to produce hypotensive effects. Of 55 DBS samples collected post-dose, a total of 52 samples were within the curve range of 0.1-50 ng/ml, where valid clonidine PK profiles were obtained. The PK parameters agreed well with the onset of hemodynamic changes measured with implanted miniature telemetry blood pressure transmitters. In comparison, only 21 samples were within the curve range of 2 to 1000 ng/ml from a HILIC-MS/MS method, which limited useful injection volume to 5 µl.