Simultaneous determination of lidocaine, bupivacaine, and their two main metabolites using gas chromatography and a nitrogen-phosphorus detector: selection of stationary phase and chromatographic conditions

Cibenzoline intoxication: effect of combined hemoperfusion-hemodialysis on plasma clearance

INTRODUCTION

Cibenzoline is an antiarrhythmic drug used to treat patients with supraventricular or ventricular arrhythmias. Cibenzoline overdose is associated with proarrhythmic and hemodynamic effects such as hypotension and congestive heart failure.

CASE REPORT

We report a case of cardiogenic shock due to cibenzoline overdose in a patient with progressive renal insufficiency.

DISCUSSION

The standard treatment of a cibenzoline intoxication is symptomatic, but we used combined hemoperfusion-hemodialysis to treat our patient.

CONCLUSIONS

This was associated with a rapid decline in plasma cibenzoline concentration and improvement of the clinical condition. However, only 28.98 mg of an estimated body pool of cibenzoline (447.2 to 806.6 mg) was removed during the 8 hours of treatment.

Effect of Fluvoxamine and Erythromycin on the Pharmacokinetics of Oral Lidocaine

Lidocaine is metabolized by cytochrome P450 3A4 (CYP3A4) and CYP1A2 enzymes, but inhibitors of CYP3A4 have had only a minor effect on its pharmacokinetics. We studied the effect of co-administration of fluvoxamine (CYP1A2 inhibitor) and erythromycin (CYP3A4 inhibitor) on the pharmacokinetics of lidocaine in a double-blind, randomized, three-way cross-over study. Eight healthy volunteers ingested daily either 100 mg fluvoxamine and placebo, 100 mg fluvoxamine and 1500 mg erythromycin, or their corresponding placebos (control) for five days. On day 6, 1 mg/kg lidocaine was administered orally. Plasma concentrations of lidocaine, monoethylglycinexylidide (MEGX) and 3-hydroxylidocaine (3-OH-lidocaine) were measured for 10 hr. During the fluvoxamine phase the area under the plasma concentration-time curve (AUC) and peak concentration (Cmax) of oral lidocaine were 305% (P<0.001) and 220% (P<0.05) of the control values. During the combination of fluvoxamine and erythromycin, lidocaine AUC was 360% (P<0.001) and Cmax 250% (P<0.05) of those during placebo. Fluvoxamine alone had no statistically significant effect on the half-life of lidocaine (t1/2), but during the combination phase t1/2 (3.8 hr) was significantly longer than during the placebo phase (2.4 hr; P<0.01). Fluvoxamine alone and in the combination with erythromycin decreased MEGX peak concentrations by approximately 50% (P<0.001) and 30% (P<0.01), respectively. We conclude that inhibition of CYP1A2 by fluvoxamine considerably reduces the presystemic metabolism of oral lidocaine and may increase the risk of lidocaine toxicity if lidocaine is ingested. The concomitant use of both fluvoxamine and a CYP3A4 inhibitor like erythromycin may further increase plasma lidocaine concentrations.

Effect of ciprofloxin on the pharmacokinetics of intravenous lidocaine

BACKGROUND AND OBJECTIVE

Recent studies have suggested that cytochrome P-450 isoenzyme 1A2 has an important role in lidocaine biotransformation. We have studied the effect of a cytochrome P-450 1A2 inhibitor, ciprofloxacin, on the pharmacokinetics of lidocaine.

METHODS

In a randomized, double-blinded, cross-over study, nine healthy volunteers ingested for 2.5 days 500 mg oral ciprofloxacin or placebo twice daily. On day 3, they received a single dose of 1.5 mg kg[-1] lidocaine intravenously over 60 min. Plasma concentrations of lidocaine, 3-hydroxylidocaine and monoethylglycinexylidide were determined for 11 h after the start of the lidocaine infusion.

RESULTS

Ciprofloxacin increased the mean peak concentration and area under plasma concentration-time curve of lidocaine by 12% (range [-6] to+46%; P<0.05) and 26% (8--59%; P 0.01), respectively. The mean plasma clearance of lidocaine was decreased by ciprofloxacin by 22% (7--38%; P<0.01). Ciprofloxacin decreased the area under the plasma concentration-time curve of monoethylglycinexylidide by 21% (P<0.01) and that of 3-hydroxylidocaine by 14% (P< 0.01).

CONCLUSION

The plasma decay of intravenously administered lidocaine is modestly delayed by concomitantly administered ciprofloxacin. Ciprofloxacin may increase the systemic toxicity of lidocaine.

The Effect of Erythromycin and Fluvoxamine on the Pharmacokinetics of Intravenous Lidocaine

Inhibitors of CYP3A4 (cytochrome P450 3A4) have a minor effect on lidocaine pharmacokinetics. We studied the effect of coadministration of the antidepressant fluvoxamine (CYP1A2 inhibitor) and antimicrobial drug erythromycin (CYP3A4 inhibitor) on lidocaine pharmacokinetics in a double-blind, randomized, three-way crossover study. Nine volunteers ingested daily 100 mg fluvoxamine and placebo, 100 mg fluvoxamine and 1500 mg erythromycin, or their corresponding placebos for 5 days. On day 6, 1.5 mg/kg lidocaine was administered IV over 60 min. Concentrations of lidocaine and its major metabolite monoethylglycinexylidide were measured for 10 h. Fluvoxamine alone decreased the clearance of lidocaine by 41% (P < 0.001) and prolonged its elimination half-life from 2.6 to 3.5 h (P < 0.01). During the combination of fluvoxamine and erythromycin, lidocaine clearance was 53% smaller than during placebo (P < 0.001) and 21% smaller than during fluvoxamine alone (P < 0.05). During the combination phase the half-life of lidocaine (4.3 h) was longer than during the placebo (2.6 h; P < 0.001) or fluvoxamine (3.5 h; P < 0.01). We conclude that inhibition of CYP1A2 by fluvoxamine considerably reduces elimination of lidocaine and may increase the risk of lidocaine toxicity. Concomitant use of both fluvoxamine and a CYP3A4 inhibitor such as erythromycin can further increase plasma lidocaine concentrations by decreasing its clearance.

Effect of Itraconazole on the Pharmacokinetics of Inhaled Lidocaine

Lidocaine is metabolized by cytochrome P450 3A4 and 1A2 enzymes (CYP3A4 and CYP1A2) in vitro. However, their relative contribution to the elimination of lidocaine depends on lidocaine concentration. We have studied the effect of a potent CYP3A4 inhibitor, itraconazole, on the pharmacokinetics of inhaled lidocaine in ten healthy volunteers using a randomized, two-phase cross-over study design. The interval between the phases was four weeks. The subjects were given orally itraconazole (200 mg once a day) or placebo for four days. On day 4, each subject inhaled a single dose of 1.5 mg/kg of lidocaine by nebulizer. Plasma samples were collected until 10 hr and the concentrations of lidocaine and its major metabolite monoethylglycinexylidide were measured by gas chromatography. The areas under the lidocaine and monoethylglycinexylidide concentration time curves were similar during both phases. No statistically significant differences were observed in any of the pharmacokinetic parameters; peak concentrations, concentration peak times or elimination half-lives of lidocaine or monoethylglycinexylidide. The clinical implication of this study is that no lidocaine dosage adjustments are necessary if it is used to prepare the airway prior to endoscopic procedures or intubation in patients using itraconazole or other inhibitors of CYP3A4.

Effect of erythromycin and itraconazole on the pharmacokinetics of oral lignocaine

Lignocaine is metabolized by cytochrome P450 3A4 enzyme (CYP3A4), and has a moderate to high extraction ratio resulting in oral bioavailability of 30%. We have studied the possible effect of two inhibitors of CYP3A4, erythromycin and itraconazole, on the pharmacokinetics of oral lignocaine in nine volunteers using a cross-over study design. The subjects were given erythromycin orally (500 mg three times a day), itraconazole (200 mg once a day) or placebo for four days. On day 4, each subject ingested a single dose of 1 mg/kg of oral lignocaine. Plasma samples were collected until 10 hr and concentrations of lignocaine and its major metabolite, monoethylglycinexylidide were measured by gas chromatography. Both erythromycin and itraconazole increased the area under the lignocaine plasma concentration-time curve [AUC(0-infinity)] and lignocaine peak concentrations by 40-70% (P<0.05). Compared to placebo and itraconazole, erythromycin increased monoethylglycinexylidide peak concentrations by approximately 40% (P<0.01) and AUC(0-infinity) by 60% (P<0.01). The clinical implication of this study is that erythromycin and itraconazole may significantly increase the plasma concentrations and toxicity of oral lignocaine. The extent of the interaction of lignocaine with these CYP3A4 inhibitors was, however, less than that of, e.g. midazolam or buspirone, and it did not correlate with the CYP3A4 inhibiting potency of erythromycin and itraconazole.

Influence of academic examination stress on hematological measurements in subjectively healthy volunteers

Some recent reports showed that a brief exposure to a mental stressor during 3-20 min may induce hematological changes in humans. The aim of the present study was to examine the effects of academic examination stress on erythron variables, such as the number of red blood cells (RBC), hemoglobin (Hb), hematocrit (Ht), mean corpuscular volume (MCV), mean cell Hb (MCH), mean cell Hb concentration (MCHC), RBC distribution width (RDW), and serum iron and transferrin (Tf). The above variables were determined in 41 students in three conditions, i.e. the stress condition (the day before a difficult oral exam) and two baseline conditions, i.e. a few weeks earlier and later. At the same occasions, subjects completed the Perceived Stress Scale (PSS), the state version of the State-Trait Anxiety Inventory (STAI) and the Profile of Mood States (POMS). Academic examination stress significantly increased Ht, Hb, MCV, MCH and MCHC and significantly decreased RDW. There were significant relationships between the stress-induced changes in the PSS, STAI and POMS scores and those in Ht, Hb, MCV and MCH (allpositive) and RDW (negative). It is concluded that academic examination stress induces significant hematological changes indicative of an increased number of large RBC and increased hemoglobinisation, which cannot be explained by shifts of fluid out of the intravascular space, concentrating non-diffusible blood constituents.

Effects of psychological stress on serum immunoglobulin, complement and acute phase protein concentrations in normal volunteers

The aim of this study was to examine the effects of academic examination stress on serum immunoglobulins (Igs), i.e. IgA, IgG, IgM, complement factors, i.e. C3c and C4, and acute phase proteins, i.e. alpha 1-acid glycoprotein (alpha 1-S), haptoglobin (Hp) and alpha 2-macroglobulin (alpha 2-M). Thirty-seven university students participated in this study. Serum was sampled a few weeks before and after as well as one day before a difficult academic examination. On the same occasions, students completed the Perceived Stress Scale (PSS). Students were divided into two groups, i.e. those with high- and low-stress perception as defined by changes in the PSS score. Academic examination stress induced significant increases in serum IgA, IgG, IgM, and alpha 2-M in students with high-stress perception, but not in these with low-stress perception. The stress-induced changes in serum IgA, C3c, and alpha 1-S concentrations were significantly higher in students with high-stress perception than in those with a low-stress perception. The stress-induced changes in serum IgA, IgM, C3c, C4, alpha 1-S, Hp and alpha 2-M were normalized a few weeks after the stress condition, whereas IgG showed a trend toward normalization. There were significant positive relationships between the stress-induced changes in the PSS and serum IgA, IgG, IgM and alpha 2-M. These findings suggest that psychological stress is accompanied by an altered secretion of serum Igs, complement factors and some acute phase proteins.