Fatal nefopam overdose

Diclofenac Concentrations in Post-Mortem Specimens-Distribution, Case Reports, and Validated Method (UHPLC-QqQ-MS/MS) for Its Determination

The aim of the research was to establish a sensitive method for the quantification of diclofenac in postmortem samples. The developed method was applied in six cases: three fetuses in which the use of abortion pills by their mothers was suspected, one case of duodenal ulcer perforation, one case of traffic accident with fatal outcome, and one acute renal failure in which the distribution of diclofenac was examined. The analyses were performed using liquid-liquid extraction of postmortem samples and the quantification of diclofenac via ultra-high performance liquid chromatography, coupled with triple quadrupole tandem mass spectrometry. Gradient elution using a C18 column was applied. Electrospray ionization measurement in positive multiple reaction monitoring mode was used. Diclofenac-d4 was used as an internal standard. The validation parameters were as follows: lower limit of quantification: 0.5 ng/mL, linearity of calibration curve: 0.5-500 ng/mL, intra- and interday accuracies and precisions: not greater than 15%; recovery values: 72.0-102.2%, and matrix effect: 2.2-28.0%. The developed method enabled the determination of diclofenac in human postmortem biological fluids (blood, urine, vitreous humor, bile, and stomach content), tissues (placenta, kidney, liver, and heart), and in exhumated fetus bones, with high recovery, sensitivity, precision, and accuracy.

[Thirty years of nefopam abuse in France]

AIM OF THE STUDY

The use of nefopam is constantly increasing in France. The objectives of this study were to quantify the intensity of the drug dependence signal, to identify the populations at risk and the risk factors of dependence.

METHODS

All serious and non-serious cases of misuse, abuse, drug dependence, overdose and withdrawal syndrome reported to the French Addictovigilance Network since 1988 were reviewed. An analysis of nefopam reimbursement data from the French national EGB (échantillon généraliste des bénéficiaires) database for the period 2006-2017 was also performed.

RESULTS

The drug dependence profile of nefopam is close to that of a psychostimulant. Our literature review and the analysis of spontaneous reports confirm the risk of abuse and dependence of nefopam. In addition to a frequent psychiatric history (depression, psychosis, anxiety), nearly half of the patients also present addictive disorders, including more than one-third with opioid-dependence. In almost half of the 120 reported cases, the main adverse reaction was dependence and the frequency of serious effects was greater than 40%. In nearly 70% of the reported cases, the use was associated with chronic pain, which might explain the prolonged use. Moreover, the analysis of data on the reimbursement of nefopam in the general population showed that one French person out of two, having a prescription for nefopam, presented chronic pain. However, nefopam is only indicated in the treatment of acute painful conditions. Although it does not seem to be associated with a greater risk of abuse or dependence, taking the drug orally is another very frequent off-label use that needs to be regulated.

CONCLUSION

In France, the prescription of nefopam outside of its marketing authorization is regrettable, because it contributes to the development of abuse and drug dependence.

Status epilepticus caused by nefopam

Nefopam, a centrally acting analgesic, has been used to control postoperative pain. Reported adverse effects are anticholinergic, cardiovascular or neuropsychiatric. Neurologic adverse reactions to nefopam are confusion, hallucinations, delirium and convulsions. There are several reports about fatal convulsive seizures, presumably related to nefopam. A 71-year-old man was admitted for surgery for a lumbar spinal stenosis. He was administered intravenous analgesics : ketorolac, tramadol, orphenadrine citrate and nefopam HCl. His back pain was so severe that he hardly slept for several days; he even needed morphine and pethidine. At 4 days of administration of intravenous analgesics, the patient suddenly started generalized tonic-clonic seizures for 15 seconds, and subsequently, status epilepticus; these were not responsive to phenytoin and midazolam. After 3 days of barbiturate coma therapy the seizures were controlled. Convulsive seizures related to nefopam appear as focal, generalized, myoclonic types, or status epilepticus, and are not dose-related manifestations. In our case, the possibility of convulsions caused by other drugs or the misuse of drugs was considered. However, we first identified the introduced drugs and excluded the possibility of an accidental misuse of other drugs. Physicians should be aware of the possible occurrence of unpredictable and serious convulsions when using nefopam.

Nefopam enhances the protective activity of antiepileptics against maximal electroshock-induced convulsions in mice

Nefopam is a centrally acting non-opioid analgesic with a mechanism of action that is not completely understood. Adverse effects associated with the therapeutic use and overdose of nefopam are mainly associated with the central nervous system, such as hallucinations, cerebral edema and convulsions. The aim of this study was to assess the effect of nefopam on the electrical threshold and its influence on the protective activity of antiepileptic drugs in the maximal electroshock test in mice. A 5 mg/kg dose of nefopam significantly elevated the electric seizure threshold, while a dose of 1 mg/kg failed to protect mice against electroconvulsion. At a subthreshold dose of 1 mg/kg, nefopam significantly enhanced the anticonvulsant activity of valproate against electroconvulsions. The protective activity of phenobarbital and phenytoin was significantly enhanced by co-administration of nefopam at the 5 mg/kg dose, but this same dose of nefopam failed to affect the protective activity of carbamazepine. In conclusion, nefopam exerts an anticonvulsive effect when given alone and significantly enhances the protective activity of certain antiepileptic agents against electroconvulsions induced in mice.