Three homicides with darts tainted with succinylcholine: autopsy and toxicology.

In emergency departments, intoxication with the muscle relaxant succinylcholine (SUX) often leads to a potentially lethal respiratory paralysis or other deleterious side effects. However, homicide cases with SUX poisoning are very rare because the toxic or lethal concentration ranges of SUX have not yet been determined. We described three uncommon homicide cases due to acute poisoning by darts contaminated with SUX. All the victims died quickly (less than 30 min) after being shot by an especially designed dart gun. Succinylmonocholine (SMC), a metabolite of SUX, was used as a marker to detect the latter. HPLC-MS/MS analysis demonstrated the presence of SUX in the droplet residues of the darts and SMC in the blood and urine in all cases. SMC concentrations of 0.45, 14.0, and 17.9 ng/ml were detected in the victims' blood and 259.0 ng/ml in the urine from the third case. The main pathological changes consisted of hemorrhage of the injured soft tissues, visceral congestion, severe pulmonary edema, and multifocal petechial hemorrhage of the heart and lungs. Taken together, the findings supported a diagnosis of fatal SUX poisoning. Futhermore, our study provided a reference for the lethal concentrations of SUX poisoning.

Nurse induced respiratory depression by succinylcholine--the 'hero syndrome'.

A nurse administered the neuromuscular blocking agent succinylcholine (SUX) to at least one patient and gave first aid in the therapy of unexpected respiratory depression. SUX is regarded as an undetectable and thus perfect poison due to its short half-life and degradation to the endogenous compounds choline and succinic acid. However, SUX and especially its metabolite succinylmonocholine (SMC) were found in plasma and urine a few hours after administration by means of high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Compared to clinical studies, the window of detection was sufficient to gain definite proof; in other cases no samples were collected. The nurse enjoyed high reputation with the doctors. According to the court she wanted to present herself spectacularly as the first and decisive rescuer to demonstrate her special abilities and capacities, perhaps to receive a better job in the hospital. Considering the actual case, the hero syndrome is not limited to fire-fighters.

Degradation and elimination of succinylcholine and succinylmonocholine and definition of their respective detection windows in blood and urine for forensic purposes.

The muscle relaxant succinylcholine (SUX) evokes respiratory paralysis, and numerous cases of fatal SUX intoxication have been reported. Detection of SUX and its metabolite succinylmonocholine (SMC) is difficult, both due to their (bis-) quaternary structure and the extreme hydrolytic susceptibility of SUX, and data on degradation kinetics of SUX and SMC is scarce. The present study investigates the in vivo and in vitro degradation as well as elimination of both target analytes using authentic blood and urine samples from anesthetized patients. With a special focus on the urinary data and stabilization issues, this work intends to considerably enhance the forensic knowledge concerning SUX intoxications and to present the reader with practical analytical strategies to cope with such difficult cases. Eighteen subjects undergoing surgery and requiring arterial as well as bladder catheters were included in this study. Muscle relaxation was initialized with a bolus injection of 80-100 mg SUX. Blood and urine samples were either collected using paraoxonized (n = 15) or non-modified (n = 3) tubes. Sampling was performed within 6 h after SUX application following a pre-assigned schedule. Samples were processed according to a validated isotope dilution HPLC-MS/MS method using ion-pair solid-phase extraction. In blood, SUX was usually detectable for up to 10 min post-injection, while detection of SMC was possible over the whole observation period of 6 h. Effectiveness of organophosphate stabilization was proven for both analytes and is therefore recommended. In freshly secreted urine, detection windows of a minimum of 2 h as opposed to 6 h have been determined for SUX versus SMC, respectively. Considering SMC plasma kinetics, detection of the metabolite in blood and freshly secreted urine appears to be possible over a period of at least 8-24 h. Paraoxon did not enhance the stability of either target substance in urine, stabilization of urine samples is nonetheless recommended. In summary, SMC was proven to be the most promising target analyte in SUX analysis, with urine being the proposed matrix of choice for forensic applications. Furthermore, our work defines meaningful detection windows for SUX and SMC in blood and urine as routine matrices and presents sampling recommendations as well as guideline values for forensic toxicological analysis.

A prospective comparative study of interaction between lithium and modified electroconvulsive therapy.

OBJECTIVES: To compare patients on lithium and those not on lithium with regard to adverse effects while receiving ECT. METHODS: Inpatients with schizophrenia, non-organic psychosis, mania and depression, who were prescribed ECTs either on (n=27) or not (n=28) on lithium were studied. Clinicians blind to lithium-status recorded seizure parameters, interaction with succinyl choline, cardiovascular response, recovery from ECT and immediate post-ECT complications. RESULTS: The lithium group showed no significant difference in terms of seizure variables, apnea time, and recovery from anaesthesia when compared to the non-lithium group. Average maximum heart rate, average maximum systolic blood pressure and average maximum rate pressure product were significantly lower in patients who had combined lithium and ECT. In lithium patients the average time to post-ECT recovery was directly correlated with serum lithium level. CONCLUSIONS: Though concurrent lithium is by and large safe during ECT, it benefits to maintain serum lithium level at lower end of therapeutic range. However, the findings can be applied to relatively young patients with no risk factors for ECT-complications.

Succinylmonocholine analytics as an example for selectivity problems in high-performance liquid chromatography/tandem mass spectrometry, and resulting implications for analytical toxicology.

The determination and quantitation of drugs in biological matrices using high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) is becoming increasingly popular in analytical toxicology, while at the same time a growing awareness for the limits of this technique can be observed. Our group previously developed a rapid HPLC/ESI-MS/MS method for the detection and quantitation of succinylcholine (SUX) and succinylmonocholine (SMC) using ion-pairing extraction of samples with subsequent separation by gradient chromatography on a Synergi Hydro RP C18 column (4 microm, 150 x 2 mm). Identification of analytes was achieved in the multiple reaction monitoring (MRM) mode, using two characteristic ion transitions each, the respective analytes' retention time as well as co-elution of stable isotopic analogues. In both native serum as well as urine an interference with the main MRM transition of SMC was found to co-elute with this analyte, thus severely compromising the identification and quantitation of this target analyte. The interference was further shown to be eliminated from serum and urine by exposure to alkaline conditions and hence proven to share a key physicochemical property with SMC. The observed absence of the second and third most intense ion transitions of SMC in the unknown substance was the only useful distinction between both compounds.The detailed presentation of selectivity problems encountered during method development is intended to initiate further discussion on this yet underrepresented issue in HPLC/MS/MS. The present work emphasizes the need to monitor more than just one ion transition to confidently rule out signal interferences, ensure correct analyte identification as well as quantitation, and thus avoid false-positive results. In this context, the employment of minor MRM transitions for the quantitation and identification of a given analyte is presented as a satisfactory solution to HPLC/MS/MS selectivity problems, and proposed as a possible alternative to previously published approaches.

A fully validated isotope dilution HPLC-MS/MS method for the simultaneous determination of succinylcholine and succinylmonocholine in serum and urine samples.

A high performance liquid chromatography-electrospray ionization-tandem mass spectrometry (HPLC-ESI-MS/MS) method for the simultaneous detection of succinylcholine (SUX) and its metabolite succinylmonocholine (SMC) in serum and urine is presented. For internal standardization using isotope dilution, the deuterated compounds SUX-d(18) and SMC-d(3) were employed. Full validation was performed according to international guidelines. Solid-phase extraction (SPE) of acidified samples was accomplished using Strata-X polymeric reversed phase cartridges together with heptafluorobutyric acid (HFBA) as ion-pairing reagent. Separation was achieved within 13 min on a Phenomenex Synergi Hydro RP C18 column (4 microm, 150 x 2 mm) using a gradient of 5 mM ammonium formate buffer pH 3.5 and acetonitrile.To ensure the method's applicability in forensic as well as clinical toxicology, the specific demands of both research fields were taken into account, and the method was thus validated for a low and high concentration range. For both serum and urine as sample matrix, the validation revealed good intraday and interday precisions, consistently ranging below 15% for the lowest and below 10% for elevated concentrations. Accuracy was likewise good and never exceeded 10%. Extraction recovery was excellent, ranging between 88.1 and 103.9% for SUX and SMC in both tested matrices. Matrix effects were significant, the otherwise optimized extraction and detection methods, however, allowed for a very satisfactory sensitivity of the described method: For serum, the limits of detection and quantitation were determined to be 1.9 and 6.0 ng/ml for SUX, as well as 2.5 and 8.6 ng/ml for SMC, respectively; for urine, the corresponding values were established to be 1.4 and 4.0 ng/ml (SUX), as well as 1.5 and 4.9 ng/ml (SMC).The presented method was successfully applied to authentic samples of two forensic cases investigated in the institute of forensic medicine in Bonn, allowing the diagnosis of SUX intoxications.

Fall downstairs: accident, homicide or natural death?

In homicide cases a clear anatomical or toxicological cause of death is normally evident. In the following a case is described where, without clear anatomical or toxicological cause of death, the husband of the deceased-a trained anaesthesiologist-was charged with murder. Suspicion was raised since the autopsy findings did not correspond to a fatal fall downstairs but instead could be definitely ruled out as cause of death, since intracranial bleedings and cerebral contusions, the leading causes of death in fatal falls downstairs, were missing. Further suspicion was raised since electrocardiograms (ECGs), previously stated by the accused to have been recorded personally from his wife during cardiopulmonary resuscitation (CPR), were obviously faked. Additionally, an ampule of succinylcholine was missing from his emergency case. In a trial lasting more than three quarters of a year with several witnesses and experts heard by the court, the cause of death remained unclear. However, a natural cause of death and a fatal fall downstairs were ruled out. Subsequently the husband admitted during the trial to have killed his wife without elaborating on the circumstances for legal reasons. He was sentenced to prolonged imprisonment. Of special importance was that, based on the knowledge of typical autopsy findings in fatal falls downstairs, a lethal fall downstairs could be ruled out. Therefore even negative autopsy findings are of great forensic importance.

[Accidental use of suxamethonium for general anesthesia in a patient with hereditary hypocholinesterasemia that was not recognized preoperatively].

We experienced an accidental use of suxamethonium for general anesthesia in a 26-year-old woman with hereditary hypocholinesterasemia that had not been recognized preoperatively. The patient was scheduled for total colectomy as her chronic ulcerative colitis could not be controlled with medications. Routine preoperative screening such as blood cell counts, biochemical data, chest x-ray and electrocardiogram were performed but serum cholinesterase (ChE) activity was not measured. As the preoperative patient condition was good with no abnormal history, anesthesia was induced and maintained with propofol, ketamine and fentanyl as usual. For muscle relaxation, suxamethonium was used for tracheal intubation, and vecuronium was used for the maintenance. After surgery, postanesthetic course was uneventful. One year later, as the patient was pregnant and scheduled for cesarean section, the preoperative screening was done. The biological data showed a hypocholinesterasemia without liver dysfunction. Thus, previous medical records of internal medicine were cheked. Surprisingly the record showed hypocholinesterasemia when she was 15 and 21 years of ages. However, as the physicians did not recognize hypocholinesterasemia, they did not inform the patient of it. Why did the patient have no prolonged apnea and emergence after the previous anesthesia? As the surgical time was exceeded 4 hrs, plasma suxamethonium could fortunately be less than its effective concentration at emergence. However, this case strongly suggests us that preoperative screening should be done without any omission. In addition, if serum ChE activity is not examined, use of suxamethonium should be avoided.

Oxidative stress and mitochondrial glutathione in human lymphocytes exposed to clinically relevant anesthetic drug concentrations.

STUDY OBJECTIVE: To evaluate the potential of compounds commonly used in anesthesia practice to affect the intracellular oxidant-antioxidant homeostasis of peripheral blood lymphocytes at clinically relevant concentrations; and to study the changes in reactive oxygen species production and measure the mitochondrial glutathione content. DESIGN: Prospective, in vitro study. SETTING: Experimental medical research laboratory at a University Hospital. MEASUREMENTS: Lymphocytes were isolated from the peripheral blood of 15 healthy donors and incubated for 12 hours at 37 degrees C with the following drug concentrations: thiopental sodium 20 mmoL/mL, droperidol 130 micromol/mL, propofol 60 mmoL/mL, and succinylcholine 17 mmoL/mL. Reactive oxygen species (ROS) generation was determined by hydroethidine and 2',7'-dichlorofluorescein diacetate methods. Mitochondrial glutathione level was assessed using monobromobimane staining. MEASUREMENTS AND MAIN RESULTS: Thiopental-treated lymphocytes exhibited an overgeneration of ROS, but no change was detected in mitochondrial glutathione quantity. Propofol and droperidol could not induce any perturbative effect on the oxidative state of T cells, whereas succinylcholine was found to markedly affect lymphocyte oxidative state both by impairing glutathione content and promoting exaggerated production of ROS. CONCLUSION: Drugs commonly used in anesthesia practice may significantly alter the oxidative state of peripheral T cells. This mechanism could contribute to the immune suppression that occurs transiently in the early postoperative period.

Pharmacokinetics and effects of succinylcholine in African elephant (Loxodonta africana) and impala (Aepyceros melampus).

The phenomenon of slow onset of succinylcholine (Sch) effect in elephants was investigated by analyzing blood concentrations of Sch and its metabolite choline in elephant and impala. To assess whether the slow onset phenomenon is related to the pharmacokinetics of Sch following i.m. administration, we analyzed the time course of plasma concentrations of intact drug and its metabolite and determined its pharmacological effects. Blood samples were obtained from anaesthetized elephant (n=6) and impala (n=7) following i.m. administration of a lethal dose of Sch. Time from Sch injection to onset of apnoea and to death was significantly longer for elephant than impala (mean+/-S.D. apnoea 4.4+/-1.5 and 2.3+/-0.9 min, respectively; death 32.6+/-7.3 and 6.2+/-3.4 min, respectively). The C(max) was not different between elephants and impala (20.3+/-7.9 vs. 14.4+/-6.8 nmol ml-1, respectively) but the t(max) was significantly longer for elephants (23.0+/-7.6 vs. 3.7+/-2.2 min). Analysis of the plasma Sch and choline concentrations over time revealed that the relative amount of Sch entering the circulation within the first 30 s after i.m. injection is greater for impala than elephant. No greater rate in the plasma hydrolysis of Sch in elephant compared to impala was apparent.

Measurement of succinylcholine concentration in human plasma by electrospray tandem mass spectrometry.

An electrospray mass spectrometric method for the quantification of the depolarizing neuromuscular blocking agent succinylcholine (SUX) is described. An extraction method compatible with direct infusion inlet was developed and leads to an analysis cycle time of 7--8 min instead of 25 min that would be required for HPLC inlet. SUX was extracted from human plasma on C1 solid-phase cartridges and was analyzed using positive ion electrospray tandem mass spectrometry (ESI-MS/MS). SUX plasma concentrations were determined by a stable isotope dilution assay using hexadeuterosuccinylcholine diiodide (SUXd6) as the internal standard. The calibration curve was prepared using the ratio of intensities of the major product ions in the collision-induced dissociation spectrum for known concentration ratios of SUX and SUXd6 in plasma. Calibration curves for the quantification were linear from 25 to 4000 ng/ml. For intraday precision, CV were < or =6% and accuracy ranged from 98 to 103%. For the interday precision, CV were < or =10% and accuracy ranged from 90 to 102%. This method is specific, sensitive, reproducible, and practical in a clinical setting.

Determination of succinylcholine in plasma by high-pressure liquid chromatography with electrochemical detection.

The plasma concentration of the neuromuscular blocking drug, succinylcholine, is difficult to measure. We have measured concentrations of the breakdown product of succinylcholine, choline, to assess whether choline concentration gives an accurate measure of succinylcholine concentration. Choline concentration was measured by HPLC and electrochemical detection in two blood or plasma samples, one in which succinylcholine hydrolysis was inhibited by 10(-5) M physostigmine and another in which succinylcholine was completely hydrolysed in 20 min by 200 mU butyrylcholinesterase at 37 degrees C. The difference in choline content between the two samples gives the succinylcholine concentration. Ninety-five per cent recovery of choline was achieved. Choline standard curves were linear from 156 pmol ml-1 to 200 nmol ml-1. Within-day and between-day mean coefficients of variation for succinylcholine hydrolysis were small (mean (SD) 3.7% (1.2%) and 3.8% (1.6%), respectively). We conclude that this method of measuring succinylcholine concentration in blood is accurate, repeatable and relatively easy.

Determination of succinylcholine in human plasma by high-performance liquid chromatography with electrochemical detection.

An alternative HPLC method for the quantification of the depolarizing neuromuscular blocking agent succinylcholine in human plasma is described. Drug spiked plasma and patient plasma samples were extracted using a C1 solid-phase cartridge. Succinylcholine was separated on a Cyano column and quantitated using electrochemical detection at a potential of 450 mV and 750 mV. Mobile phase consisted of a mixture of phosphoric acid-acetonitrile-methanol (45:35:25) adjusted to an apparent pH of 5. Standard curves for the quantitation were linear in the range of 250-8000 ng/ml. Between-day and within-day relative standard deviations were 5.1% and 1.7%, respectively. Mean drug recovery and accuracy was 68% and 104%, respectively.

Neuromuscular blocking drug pharmacodynamics after chronic exposure to H2- antagonists.

This study tested the hypothesis that chronic exposure to H2-antagonists may affect neuromuscular function. Cimetidine or ranitidine was administered to rats for twenty one days as subcutaneously implanted biodegradable pellets. Control rats received placebo pellets. Serum cimetidine and ranitidine concentrations ranged from 0.1 to 0.5 micrograms/mL over this period. On the study day, surgically prepared anaesthetized rats received either succinylcholine (SCh) or atracurium (ATr) to achieve complete paralysis of the tibialis anterior muscle. After recovery an infusion dose of each neuromuscular blocker was titrated to produce 50% muscle paralysis with each blocker. Exposure to cimetidine or ranitidine did not alter SCh or ATr dose to maximum paralysis or the time course of recovery from the initial paralysis. SCh or ATr infusion rates required to elicit 50% paralysis were also unaffected by cimetidine or ranitidine pretreatment. These results indicate that chronic exposure to cimetidine or ranitidine at human therapeutic concentrations does not affect the neuromuscular pharmacodynamics of SCh or ATr in rats.

Suxamethonium apnoea and the isolated leg.

The anaesthetic management of a patient with an unsuspected homozygous atypical pseudocholinesterase genotype is described. Suxamethonium was administered after an arterial tourniquet had been applied to the patient's right leg. After release of the tourniquet and termination of the anaesthetic it was noted that the patient was able to move his right leg but no other part of his body. This observation was confirmed by the use of a peripheral nerve stimulator and by the patient's own recollections. It is suggested that this occurrence shows that the slow offset of neuromuscular block in patients with atypical pseudocholinesterases who have received suxamethonium is caused by long lasting effects at the neuromuscular junction rather than the continuing presence of suxamethonium in the plasma.

Pharmacokinetics of succinylcholine in man.

The pharmacokinetics of succinylcholine (SCh) 1 or 2 mg/kg was studied in 14 anesthetized patients. Arterial blood concentrations of SCh were measured using a high-performance liquid chromatographic assay. The arterial concentration vs. time data were analyzed by log-linear regression and fitted to an one-compartment model. The pharmacokinetic parameters were (SCh 1, n = 8 and 2 mg/kg, n = 6): apparent volume of distribution (16.4 +/- 14.7 and 5.6 +/- 6.8 ml/kg, mean +/- S.D.), total body clearance (40.5 +/- 38.7 and 15.0 +/- 14.8 liter/min), area under the plasma concentration-time curve (124.3 +/- 163.2 and 695.3 +/- 1008.9 min.micrograms/ml), and elimination half-life (16.6 +/- 4.8 and 11.7 +/- 4.5 sec). The rapid disappearance of SCh from the blood may be due to diffusion out of the blood vessel.

Interaction between succinylcholine and ranitidine in rats.

The hypothesis that the histamine H2 receptor blocker ranitidine potentiates neuromuscular paralysis during anaesthesia was tested in vivo in urethane anaesthetised and mechanically ventilated rats. Succinylcholine was administered as a bolus and constant-rate infusion to maintain 48.5% (+/- 2.5 SEM) tibialis anterior muscle paralysis in 14 rats. Ranitidine 2.5, 5, 10, or 20 mg.kg-1 iv, was then administered into groups of three or five rats. Ranitidine produced an immediate potentiation of neuromuscular paralysis followed by a transient reversal and then a continued steady-state potentiation. Peak potentiation occurred within 20 (+/- 3.3) sec and was maintained in all the rats to steady-state. Peak reversal was evident 70 (+/- 8.1) sec after ranitidine administration. There was an excellent relationship (r2 = 0.98, P < 0.001) between peak potentiation and serum ranitidine concentration with 50% potentiation occurring at 25.8 (+/- 1.1) micrograms.ml-1. There was a weak relationship (r2 = 0.39, P < 0.05) between peak reversal and serum ranitidine but potentiation at steady-state was not correlated to serum ranitidine concentration (r2 = 0.19, P > 0.05). These results show that ranitidine alters the neuromuscular action of succinylcholine in rats in a similar manner to cimetidine.

Rapid determination of succinylcholine in human plasma by high-performance liquid chromatography with fluorescence detection.

A high-performance liquid chromatographic method with fluorometric detection has been developed for the determination of succinylcholine in human plasma. Succinylcholine shows fluorescence at 282 nm with an excitation at 257 nm. The assay is sensitive, reproducible and linear for concentrations ranging from 100 ng/ml to 100 micrograms/ml of succinylcholine. In a pilot study the plasma concentration-time curve showed a triphasic elimination, with half-lives of 0.4, 1.2 and 8 min, respectively. In a clinical setting, drugs commonly administered during anaesthesia did not interfere with the assay. This method provides a simple and time-saving alternative to existing methods.