Acute buflomedil intoxication: a life-threatening condition

Drug treatments in patients with cardiac diseases and epilepsy

OBJECTIVE

Comorbidity between epilepsy and heart diseases is frequent.

METHODS

All drugs classified within the group of drugs for cardiovascular system according to the Anatomical Therapeutic Chemical (ATC) classification system were reviewed for their effects on seizures or epilepsy.

RESULTS

Several agents showed antiseizure properties in animal models of seizures and/or in patients with epilepsy and only few were proconvulsant. Drugs with anticonvulsant effects include mecamylamine and guanfacine (antihypertensive drugs), indapamide, amiloride, furosemide and bumetanide (diuretics), fasudil (peripheral vasodilator), bioflavonoids (vasoprotective drug), propranolol (beta blocking agent), isradipine, nimodipine, verapamil and diltiazem (calcium channel blockers: CCBs), fosinopril and zofenopril (agents acting on the renin-angiotensin system), several statins, and fenofibrate (lipid-modifying agents). Drugs with proconvulsant properties in experimental models or in patients include reserpine, buflomedil, naftidrofuryl, and clonidine and propranolol at high doses. Drug-drug interactions (DDI) between antiseizure medications (ASMs) and drugs for cardiovascular system were also searched in two leading publicly accessible drug compendia. The most important DDIs occur between enzyme-inducing (EI) ASMs and ivabradine, ranolazine, macitenan and between EI-ASMs and the CCBs felodipine, nicardipine, nisoldipine, and verapamil. Simvastatin and atorvastatin are the lipid-modifying agents with more DDIs with EI-ASMs. Several pharmacodynamic interactions have been also documented.

DISCUSSION AND CONCLUSIONS

Available data show that the treatment of patients with epilepsy and vascular comorbidities is challenging and requires the appropriate knowledge of pharmacological properties of drugs and drug interactions.

The value of population pharmacokinetics and simulation for postmarketing safety evaluation of dosing guidelines for drugs with a narrow therapeutic index: buflomedil as a case study

Population pharmacokinetics and simulation techniques currently play an important role in new drug development. This paper illustrates the potential value of those methods in postmarketing safety assessment, using buflomedil in elderly patients as an example. We retrospectively assessed the risk of buflomedil overdosing associated with the latest dosing recommendations of the French Drug Agency (AFSSAPS). First, buflomedil concentrations measured in 24 elderly patients were analysed with a nonparametric population approach. Then, the pharmacokinetic model was used to perform a 1000-patient Monte Carlo simulation for the two recommended buflomedil dosage regimens. The maximum concentrations calculated after 10 days of therapy were compared with levels observed in reported cases of toxicity to assess the probability of overdosing. A three-compartment model best fit concentration data. Population predictions showed little bias (-0.14 mg/L) and good precision (8.73 mg(2) /L(2)). Overall results of the simulation study showed that the application of the two recommended dosage regimens of buflomedil was associated with overdosing (C(max) > 10 mg/L) and potential toxicity in 2.9% of geriatric patients. In patients with mild renal impairment, who may receive the higher-dosage regimen by therapeutic error, the probability of overdosing was 6.2%. Despite specific dosing recommendations in case of renal impairment, this study shows that the use of buflomedil could be associated with significant risk of overdosing in geriatric patients. Such results might have enhanced decision-making when buflomedil safety was reassessed by AFSSAPS in 2006. The retrospective case of buflomedil illustrates how these methods may be valuable in postmarketing safety evaluation of potentially toxic drugs.

Lactate is an ideal non-invasive marker for evaluating temporal alterations in cell stress and toxicity in repeat dose testing regimes

Technological developments are driving in vitro methods towards integrated "omic" strategies. However, there is still an over reliance on classical viability assays for dose range finding. Such assays are not readily suited to the investigation of subtle alterations in cell function and most require termination of the experiment, which makes it difficult to monitor temporal alterations in repeat-dose long term exposure experiments. To this end, we investigated the use of lactate production as a marker of cell stress in long term repeat dose experiments. We conducted daily exposures to eight compounds at five concentrations for 14 days on human renal proximal tubular cells (RPTEC/TERT1), human hepatoma cells (HepaRG) and mouse fibroblasts (BALB-3T3) cells. Compounds were chosen from a training set used in the 7th EU Framework project Predict-IV and consisted of amiodarone, diclofenac, troglitazone, cadmium chloride, cephaloridine, cidofovir, cyclosporine A and buflomedil. At days 1, 3, 7 and 14, lactate was measured in the supernatant medium. At day 14, cells were assayed for resazurin reduction capability and subsequently lysed in methanol for ATP determination. Compound-induced loss of viability was comparable across all cell lines. For all cell types, when cell viability was compromised at day 14, lactate production was induced during the treatment period. In some situations, lactate also fell below control values, indicating cell death. Thus, temporal alterations in supernatant lactate provides information on the time and concentration of stress induction and the time and concentration where cell death becomes the dominant factor. Supernatant lactate production is a simple, cheap and non-invasive parameter. Since many molecular pathways converge on the glycolytic pathway, enhanced lactate production may be considered as a global marker of sub-lethal injury and thus an ideal marker for investigating temporal alterations in long term repeat dose testing in vitro regimes.

The use of buflomedil in reduction mammaplasty for a previously irradiated breast: a case report

In recent years, lumpectomy combined with breast irradiation and chemotherapy, as a part of conservation therapy for breast cancer, has well-established results. Little has been published on reduction mammoplasty for breast-irradiated patients. These patients have increased risks of nipple necrosis, wound complications, and delayed healing. Breast reduction techniques that rely on minimum skin undermining combined with the use of buflomedil may prevent major postoperative complications in breast-irradiated patients. Buflomedil was administered intraoperatively and for 14 days after the procedure. The use of buflomedil in reduction mammaplasty for a previously irradiated breast patient has not been heretofore described. The case of a 58-year-old woman who underwent bilateral breast reduction after breast conservation therapy is reported.

Differential modulation of IL-8 and TNF-alpha expression in human keratinocytes by buflomedil chlorhydrate and pentoxifylline

Pentoxifylline (PTX) is a methylxanthine derivative used in a wide range of dermatoses. As well as its hemorrheologic activity, PTX has anti-inflammatory properties. Buflomedil chlorhydrate (BC) is another hemorrheological drug with peripheral vasodilatory action, whose clinical uses are similar to those of PTX. Both drugs increase intracellular levels of cAMP, either secondary to phosphodiesterase inhibition (PTX) or adenyl-cyclase stimulation (BC). Long-term cultures of normal human keratinocytes were prepared in a free-serum medium, and stimulated with 1 mg/ml of phorbol 12-myristate 13-acetate (TPA) and PTX or BC (100-1000 micrograms/ml). Levels of TNF-alpha, IL-1 alpha, IL-1 beta, IL-8 and TGF-beta 1 using ELISA and Northern blot or RT-PCR techniques were measured. TPA-induced TNF-alpha and IL-8 release from keratinocytes. TPA did not induce IL-1 alpha or IL-1 beta release of keratinocytes. TPA increased RNA expression of the TNF-alpha, IL-1 alpha, IL-1 beta, IL-8 and TGF-beta 1. BC diminished TPA-induced TNF-alpha and IL-8 release from keratinocytes; in the case of IL-8 it is possible that this inhibition occur to transcriptional level. Moreover PTX was unable to inhibit TNF-alpha and IL-8 synthesis and expression. PTX and BC reduced TPA-induced IL-1 alpha and beta expression. It is possible that BC action is specifically exerted on keratinocytes, because we did not find similar results with TNF-alpha and IL-8 synthesis in mononuclear peripheral blood cells.

Buflomedil poisoning: five cases with cardiotoxicity

OBJECTIVE

To report cardiotoxicity of buflomedil.

SETTING

Medical intensive care unit of a university hospital.

PATIENTS

Five patients admitted to the hospital since 1985 for buflomedil poisoning. The amount ingested was known for only three patients (3-10.8 g).

RESULTS

The five young women were admitted to the hospital because of generalized seizures or myoclonic jerks. Cardiac arrest (asystole) occurred for two of them on admission, 1 and 3 h after ingestion. Electrocardiogram revealed atrio-ventricular and intraventricular conduction abnormalities, increased QT interval and flattened T wave, decreasing after sodium bicarbonate infusion in two cases. The patients received mechanical ventilation, gastric lavage, oral activated charcoal, and clonazepam or valproic acid for convulsions or myoclonic jerks. Epinephrine was administered for cardiac arrest. Sodium bicarbonate was infused in one patient on the basis of slightly prolonged QRS duration and in two patients due to cardiac arrest. Clinical outcome was good and without sequelae for all five patients after a few days in the intensive care unit.

CONCLUSION

Clinical and electrocardiographic symptomatology of buflomedil poisoning suggests direct cardiotoxicity, which could be related to possible sodium antagonist properties.

[Severe acute buflomedil poisoning]

The severity of the acute intoxication from buflomedil, a vasodilator with papaverinic and alpha-adrenolytic effects, remains generally underestimated. We report the case of a 18-year-old girl who ingested a high amount of buflomedil. Two hours later, she developed seizures and ventricular arrhythmias. On admission to the ICU, she was in circulatory arrest followed by deep coma with mydriasis (GCS = 3). Buflomedil blood concentration, 2 hours after admission, was 97.3 mg.L-1. Toxicological screening for other drugs was negative. Therapy included external chest compressions tracheal intubation, mechanical ventilation, epinephrine and gastric lavage. The haemodynamic status improved within the first 24 h, although she remained comatose until the fifth day. She was discharged the eight day after her admission. This observation demonstrates that the potential severity of buflomedil poisoning is mainly due to early cardiac complications. Treatment remains purely supportive.