The rationale of opportunistic bilateral salpingectomies (OBS) during benign gynaecological and obstetric surgery: a consensus text of the Flemish Society of Obstetrics and Gynaecology (VVOG)

Ovarian cancer (OC), is a disease difficult to diagnose in an early stage implicating a poor prognosis. The 5-year overall survival in Belgium has not changed in the last 18 years and remains 44 %. There is no effective screening method (secondary prevention) to detect ovarian cancer at an early stage. Primary prevention of ovarian cancer came in the picture through the paradigm shift that the fallopian tube is often the origin of ovarian cancer and not the ovary itself. Opportunistic bilateral salpingectomy (OBS) during benign gynaecological and obstetric surgery might have the potential to reduce the risk of ovarian cancer by as much as 65 %. Bilateral risk-reducing salpingectomy during a benign procedure is feasible, safe, appears to have no impact on the ovarian function and seems to be cost effective. The key question is whether we should wait for a RCT or implement OBS directly in our daily practice. Guidelines regarding OBS within our societies are therefore urgently needed. Our recommendation is to inform all women without a child wish, undergoing a benign gynaecological or obstetrical surgical procedure about the pro's and the con's of OBS and advise a bilateral salpingectomy. Furthermore, there is an urgent need for a prospective registry of OBS. The present article is the consensus text of the Flemish Society of Obstetrics and Gynaecology (VVOG) regarding OBS.

Focus on cannabinoids and synthetic cannabinoids

The recent emergence of a multitude of synthetic cannabinoids (SCs) has generated a wealth of new information, suggesting the usefulness of state-of-the-art on lato sensu cannabinoids. By modulating a plurality of neurotransmission pathways, the endocannabinoid system is involved in many physiological processes that are increasingly explored. SCs desired and adverse effects are considered to be more intense than those observed with cannabis smoking, which is partly explained by the full agonist activity and higher affinity for cannabinoid receptors. Neurological and cardiovascular side effects observed after cannabinoid poisoning generally respond to conventional supportive care, but severe outcomes may occur in a minority of cases, mainly observed with SCs. The likelihood of severe abuse and addiction produced by SCs are of concern for the scientific community also interested in the potential therapeutic value of cannabinoids.

Bile and blood ratios of cyclosporin and its metabolites in patients on continuous infusion during the first three weeks after liver transplantation

Ten patients with orthotopic liver transplants were investigated during routine therapeutic monitoring to study the relationship between the concentrations of cyclosporin and its metabolites in blood, bile and urine, and whether this information can provide early signs of severe hepatic disorders post-transplantation. Cyclosporin (Sandimmun®) was administered by continuous infusion at a constant rate of 5 mg/kg/day, modified to keep the blood cyclosporin concentration within the target range (400 to 500 μg/L). The concentrations of cyclosporin and combined cyclosporin-metabolites in blood, bile and urine were assayed daily during the 3 post-transplantation weeks that the patients spent in intensive care.All patients developed cholestatis and cytolysis during the first week. The severity of these liver transplant disorders increased in 5 patients and decreased in the other 5 in the second week. The pharmacokinetics of cyclosporin differed in the 2 groups: in patients without severe hepatic disorders, the blood metabolites/cyclosporin ratio (M/C) stabilised at 1.2 ± 0.4 in week 2 and at 0.8 ± 0.2 in week 3, bile cyclosporin/blood cyclosporin (bile C/blood C) fluctuated around 13.5 (13.5 ± 9.5 in week 2 and 13.5 ± 9.0 in week 3) and the bile metabolite/blood metabolite (bile M/blood M) ratio was very high and variable (131 ± 86 in week 2 and 159 ± 116 in week 3). Metabolites significantly accumulated in the blood of patients with severe hepatic disorders (M/C = 2.8 ± 0.6 in week 2 and 3.5 ± 1.0 in week 3); bile C/blood C (2.6 ± 2.1 in week 2 and 3.4 ± 1.1 in week 3) and bile M/blood M (11.9 ± 7.8 in week 2 and 12.5 ± 7.9 in week 3) significantly decreased and showed less interindividual variability.Blood cyclosporin is usually monitored to help optimise the dosage. However, if this was extended to include the monitoring of metabolites in the blood, and cyclosporin and metabolites in the bile, it could provide an early indication of severe hepatic disorders in patients with transplanted livers.

An information campaign on aminoglycosides use during septic shock failed to improve the quality of care

BACKGROUND

Septic shock remains a major cause of death in intensive care units (ICU) and an inappropriate antibiotic regimen worsens the prognosis. The aim of the study was to assess the impact of an information campaign on modalities of prescription of aminoglycosides in septic shock.

STUDY DESIGN

A prospective observational study.

METHODS

Consecutive septic shock patients admitted to the surgical ICU over a 2-year period were included. An information campaign allowed to differentiate between a pre- (P1) and a post- (P2) interventional period. The campaign clarified the rules and requirements for pharmacological monitoring of aminoglycosides. The main objective was to increase the rate of prescription of peak serum aminoglycoside following the first intravenous injection.

RESULTS

One hundred and forty-eight patients (P1=76 and P2=72) were finally included into the study. Similar clinical characteristics were observed during both periods. The rate of prescription of peak serum aminoglycoside following the first injection was performed in 49% (P1) versus 65% (P2), P=0.09. The length of stay in ICU was 16 days [extremes: 1-74] (P1) versus 17 days [extremes: 1-133] (P2) (P=0.84). Inhospital mortality was 28% (P1) versus 26% (P2), P=0.86.

CONCLUSIONS

An information campaign describing the modalities of prescription of aminoglycosides in septic shock failed to improve medical practices and patient outcomes. A mobile team of antibiotics could be useful in daily practice.

Pharmacokinetics of mycophenolic acid in kidney transplant patients receiving sirolimus versus cyclosporine

INTRODUCTION

Mycophenolic acid (MPA) pharmacokinetics exhibit large variability in transplant recipients and may be altered due to concurrent immunosuppressants. Little is known about the influence of sirolimus (SRL) on MPA pharmacokinetics in kidney transplant patients.

METHODS

We studied the areas under concentration-time curves (AUC) for MPA in 15 patients receiving immunosuppression combining SRL with mycophenolate mofetil (MMF). The pharmacokinetic measurements were performed in all patients using three MMF dosing regimens (0.5 g twice a day, 0.75 g twice a day, 1 g twice a day). Similar blood AUC profiles were also sampled from 12 patients treated with a fixed dose of MMF 1 g twice a day and cyclosporine (CsA). MPA was measured using HPLC; the AUC0-12 of MPA was determined by the trapezoidal method using four sampling time points: C0, C1, C3, C5.

RESULTS

While patients on SRL were receiving 0.75 g MMF twice a day, mean AUC0-12 and C0 values of MPA were comparable to those of patients receiving CsA and 1 g MMF twice a day (54.1 +/- 17.6 and 3 +/- 1.87 vs 51.7 +/- 16.7 mg.h/L and 2.76 +/- 1.57 mg/L, respectively). On the other hand, 0.5 g MMF twice a day with SRL therapy resulted in AUC0-12 and C0 values of MPA of 32.3 +/- 12.6 mg.h/L and 2.32 +/- 1.72 mg/L, respectively, whereas, 1 g MMF twice a day with SRL resulted in AUC0-12 and C0 values of MPA of 70.9 +/- 19.3 mg.h/L and 4.7 +/- 2.44 mg/L, respectively.

CONCLUSIONS

These findings demonstrate that MPA exposure in the presence of SRL is higher than that with CsA. It appears that the MMF dose should be reduced to 0.75 g twice a day in patients receiving SRL to obtain AUC0-12 of MPA levels comparable to that in patients treated with CsA and MMF 1 g twice a day.

Short-term pharmacokinetics and brain distribution of mecamylamine as a preliminary to carbon-11 labeling for nicotinic receptor investigation

As a preliminary to development and evaluation of labeled mecamylamine as a potential in vivo imaging ligand for human central nicotinic receptors (nAchRs), this work was intended to determine whether the pharmacokinetic properties of mecamylamine are suitable for experimental studies using (11)C-radiolabeled mecamylamine preliminary to positron emission tomography (PET) in humans. An original gas chromatographic method for rapid and simple determination of mecamylamine in biological samples was developed and validated (within run precision, 3.8-5.2%; between assay variation, 5.3-6.9%; assay accuracy, 5.6-11.8%). The results of the pharmacokinetic investigation in the rat demonstrated a very fast clearance of mecamylamine from blood [half-life, 1.2 h; clearance (CL), 1.2 L/kg/h) concomitant with an uptake that was higher in kidney, intermediate in lung, and lower in heart, liver, and brain. Brain tissue kinetics of mecamylamine showed a similar pattern for all the regions, with a rapid increase followed by a plateau after 15 min. This plateau differed according to the region of the brain; it was higher in colliculi, hippocampus, and cortex (area of high density of nAchRs) than in cerebellum or white matter (area with a limited population of nAchRs). No other lipophilic metabolites that were able to disturb the specific binding to nAchRs were identified during the investigation. Thus, mecamylamine shows peculiar qualities making it a good candidate for carbon-11 labeling for experimental studies in view of final PET imaging.

Pharmacokinetics of antifungal agents in onychomycoses

Onychomycosis is caused by infection by fungi, mainly dermatophytes and nondermatophyte yeasts or moulds; it affects the fingernails and, more frequently, the toenails. Dermatophytes are responsible for about 90 to 95% of fungal infections. Trichophyton rubrum is the most common dermatophyte; Candida albicans is the major nondermatophyte yeast. Although topical therapy of onchomycosis does not lead to systemic adverse effects or interactions with concomitantly taken drugs, it does not provide high cure rates and requires complete compliance from the patient. At present there are 3 oral antifungal medications that are generally used for the short term treatment of onychomycosis: itraconazole, terbinafine and fluconazole. The persistence of these active drugs in nails allows weekly administration, reduced treatment or a pulse regimen. Good clinical and mycological efficacies are obtained with itraconazole 100 to 200 mg daily, terbinafine 250mg daily for 3 months, or fluconazole 150 mg weekly for at least 6 months. Itraconazole is a synthetic triazole with a broad spectrum of action. It is well absorbed when administered orally and can be detected in nails 1 to 2 weeks after the start of therapy. The nail : plasma ratio stabilises at around 1 by week 18 of treatment. Itraconazole is still detectable in nails 27 weeks after stopping administration. Nail concentrations are higher than the minimum inhibitory concentration (MIC) for most dermatophytes and Candida species from the first month of treatment. The elimination half-life of itraconazole from nails is long, ranging from 32 to 147 days. Terbinafine is a synthetic allylamine that is effective against dermatophytes. Terbinafine is well absorbed from the gastrointestinal tract, and the time to reach effective concentrations in nail is 1 to 2 weeks. The half-life is from 24 to 156 days, explaining the observed persistence of terbinafine in nails for longer than 252 days. Fluconazole is a bis-triazole broad spectrum antifungal with high oral bioavailability. The uptake of fluconazole by nail increases with the length of treatment, and nail : plasma ratios are generally 1.5 to 2 at steady state. Fluconazole concentrations exceed the MIC for Candida species soon after the start of treatment. Fluconazole concentrations fall slowly after the drug is stopped, with a half-life of 50 to 87 days, and fluconazole is still detectable in nails 5 months after the end of treatment. All these drugs are potent inhibitors of cytochrome P450 (CYP) enzymes and may increase the plasma concentrations of concomitantly used drugs. Itraconazole inhibits CYP3A4. Fluconazole inhibits CYP3A4, but to a lesser degree than itraconazole, CYP2C9 and CYP2C19. Terbinafine inhibits CYP2D6.

Pharmacokinetics of all-trans retinoic acid, 13-cis retinoic acid, and fenretinide in plasma and brain of Rat

We have measured the pharmacokinetics of three retinoids, all-trans retinoic acid, 13-cis retinoic acid, and fenretinide in rat blood and rat brain [especially white matter (WM) and gray matter (GM)] to help select retinoids for treating human malignant glioma. All-trans retinoic acid permeated well into the WM, giving peak concentration in WM of 25.7 microg/g, 6 to 7 times higher than the peak serum concentration. There was less 13-cis retinoic acid in WM: area under the curve (AUC)(0-->infinity) WM/AUC(0-->infinity) serum = 18.00 microg ml(-1) h/32.67 microg ml(-1) h. The ratio WM/GM was over 1 for these two compounds, but the half-lives were short in the serum and cerebral tissue (0.57-1.02 h). Fenretinide had different pharmacokinetics: the peak concentrations were in serum (1.7 microg/ml) and WM (1.2 microg/ml)-low, but the AUC(0-->infinity) was large (25.55 microg ml(-1) in serum and 57.53 microg ml(-1) in WM) due to its long elimination half-life (13.78 h in serum and 17.77 h in WM). These findings provide information that may be used to select a retinoid and establish therapeutic regimens that provide optimal efficacy with minimal toxicity.

Benzodiazepines: toxic serum concentrations in positive enzyme immunoassay responses

A total of 588 blood specimens collected in an emergency unit were screened for benzodiazepines (BZDs) using enzyme-multiplied immunoassay and gas chromatography. Two-hundred eighty-five samples were positive for BZDs, and 303 samples that were negative by EMIT included 20 samples with BZDs detectable by gas-liquid chromatography. A total of 15 BZDs were identified, and the most frequently occurring were nordiazepam, bromazepam, diazepam, and alprazolam. Individual BZDs were found in 74% of cases, but some samples contained two, three, or even four BZDs. There is a risk of missing intoxication by BZDs with low therapeutic range and/or low cross-reactivity (alprazolam, bromazepam, flunitrazepam). There is a risk of misinterpreting a positive result for some BZDs with high therapeutic range and/or high cross-reactivity (nordiazepam), which may reflect a pharmacologically ineffective concentration. A semiquantitative analysis is inappropriate even when the identity of BZD is known. Immunoassays are the only methods presently available for use in emergencies, but physicians must be clearly informed of their limitations and interpret results with caution.

Clinical pharmacokinetics of fluconazole in superficial and systemic mycoses

The bis triazole agent fluconazole is used widely in the treatment of superficial and deep mycoses. A single oral dose of fluconazole 150 mg gives a mean long term clinical cure rate of 84 +/- 5% and is considered a valuable alternative to other topical antifungal drugs for vaginal candidiasis. A clinical cure rate of 90.4% for oropharyngeal candidiasis was obtained with 100mg daily for a minimum of 14 days; however, as for the other azoles the rate of relapse was large (40%) in immunocompromised patients. A daily dose of 100mg for at last 3 weeks gave satisfying outcomes for oesophageal candidiasis. Most patients (71 to 86%) with signs and symptoms of urinary tract candidiasis show beneficial clinical results when given oral fluconazole 50mg for several weeks. Fluconazole 50 to 150 mg given for weeks or months results in over 90% clinical cure or improvement for cutaneous mycosis including tinea, pityriasis, cryptococcosis and candidiasis. Prolonged (6 to 12 months) fluconazole 150 mg once a week is needed to treat onychomycosis successfully. Higher oral doses (200 to 400 mg daily) for long periods are generally used to treat deep mycoses such as meningitis, ophthalmitis, pneumonia, hepatosplenic mycosis and endocarditis. Fluconazole is effective for treating the fungal peritonitis which can complicate continuous ambulatory peritoneal dialysis (CAPD). A regimen of 50 mg intraperitoneally or 100 mg orally was used in these patients with impaired renal function. The dosage schedules used to treat disseminated fungal infections due to systemic mycoses with different or multiple foci of infections vary widely, with doses of 50 to 400 mg given orally or intravenously for between 1 week and several months. The most recent clinical reports have investigated the use of prophylaxis with fluconazole 100 to 400 mg daily, in immunocompromised patients. Fluconazole is found in body fluids such as vaginal secretions, breast milk, saliva, sputum and cerebrospinal fluid at concentrations comparable with those determined in blood after single or multiple doses. There is an excellent linear plasma concentration-dose relationship, but the mycological and clinical responses do not appear to be well correlated with the dose. A total maximum daily dose of 1600 mg is recommended to avoid neurological toxicity. Data from pharmacokinetic studies conducted in patients, mainly those with AIDS, and using a 1-compartment model give very constant parameters similar to those obtained in healthy individuals. Bioavailability, measured in HIV-positive patients and those with AIDS, exceeded 93% for tablets, suspension and suppositories. The time to reach peak plasma concentrations (tmax) was 2.4 to 3.7 hours. The peak plasma drug concentration (Cmax) obtained after a 100 mg oral dose was 2 mg/L. Areas under the concentration-time curve (AUC) obtained in different studies all correlate well with the dose (r = 0.926). The AUC determined after 200 and 25 mg suppositories were similarly well correlated. Hypochlorhydria does not affect the absorption of fluconazole, neither does food intake, race (Japanese or Caucasian) or gastrointestinal resection. Binding to plasma protein is low (11.14%) and is increased to 23% in cancer patients. Fluconazole is rapidly distributed to the tissue, where it accumulates. Tissues fall into 1 of 4 groups of increasing drug concentration: blood, bone and brain have the lowest concentrations, and spleen has the highest. The volume of distribution (Vd) remains stable at 46.3 +/- 7.9L and is considered to be an 'invariant' parameter across species. Fluconazole is poorly metabolised and is mainly eliminated unchanged in the urine. The percentage of the dose recovered in the urine in 48 hours is close to 60%. Concentrations in the urine are high and the half-life (t1/2) is long (37.2 +/- 5.5h) in patients, mainly those with AIDS, which is not significantly different from the t1/2 (31.4 +/- 4.7 hours) in healthy individuals. (ABSTRACT TRUN

A comprehensive investigation of plasma and brain regional pharmacokinetics of imipramine and its metabolites during and after chronic administration in the rat

The relationship between the serum imipramine concentration and its antidepressant effects remain undefined despite > 30 years of clinical investigation. No study to date has assessed the kinetic relationships between the concentrations of imipramine and its metabolites in plasma and in various brain structures. In this study, we examine the pharmacokinetics of imipramine (IMI) and its desmethylated and hydroxylated metabolites in rats given IMI chronically (20 mg/kg, intraperitoneally twice a day for 14 days). The concentrations in serum, cerebrospinal fluid, and six brain structures were measured by high-performance liquid chromatography at 13 different times from 0.5 to 120 h after the end of treatment. The concentrations of IMI, desipramine (DMI), and didesmethylimipramine (DDMI) in brain tissue were much higher than in the serum; concentrations were maximal at 1-2 h in the serum and the brain, which is indicative of the rapid metabolism of IMI with immediate and massive entry of the metabolites into the brain. The elimination halflives of desmethylated compounds increased with the degree of desmethylation, and DDMI was still present in brain tissue 96 h after the end of treatment. These results suggest that DDMI should be taken into account in clinical investigations of the effects of serum concentrations of IMI. The hydroxylated metabolites 2-OH imipramine (2-OH IMI) and 2-OH desipramine (2-OH DMI) were detected in serum, but not in cerebral tissue. The 10-OH metabolites were detected in both serum and brain, but the antidepressant action of these metabolites have not been clearly established. Finally, there were significant differences in the distributions of IMI and several of its metabolites in brain structures. Such differences may have clinical relevance if they also occur in humans.

Positron emission tomographic studies of [11C]MDL 72222, a potential 5-HT3 receptor radioligand: distribution, kinetics and binding in the brain of the baboon

The drug MDL 72222, a selective 5-HT3 receptor antagonist, was labelled with 11C and evaluated for distribution kinetics in brain and in vivo binding to 5-HT3 receptors using cold MDL 72222 challenge and positron emission tomography (PET), in three anaesthetized baboons. After tracer doses of [11C]MDL 72222 (i.v. bolus), 11C radioactivity was equally partitioned between plasma and blood cells and readily crossed the blood-brain barrier; it was distributed heterogeneously into 17 different structures of the brain. The kinetic curves for 11C in tissue showed a rapid initial uptake, followed by a slower ascending phase, up to about the twentieth minute and by a plateau, until the end of experiment (90 min). The plateau values indicated marked uptake in brain which, however, varied according to the region considered. In inhibition studies with cold MDL 72222 (1 mg.kg-1) as pretreatment, co-injection or displacement, no clear-cut effects on the kinetics of [11C] MDL 72222 in brain were detected in any region, including those known to be rich in 5-HT3 receptors. These observations suggest that specific binding to 5-HT3 receptors was not detectable in brain in vivo, because of the high lipophilicity (thus a great capacity for non-specific binding) of MDL 72222. These negative findings may also result from both the possible suboptimal affinity of MDL 72222 for 5-HT3 receptors in vivo and the relatively low density of 5-HT3 receptors present only in selected areas of the mammalian brain. This study is a step in the search of selective 5-HT3 receptor radioligands, adequate for in vivo applications. Slow clearance of [11C]MDL 72222 from brain tissue in baboons, should be accounted for in clinical pharmacokinetic investigations for optimal posology considerations.

Clinical pharmacokinetics of fluconazole

Fluconazole was recently developed for the treatment of superficial and systemic fungal infections. Triazole groups and insertion of 2 fluoride atoms increase the polarity and hydrosolubility of the drug, allowing it to be used in a parenteral form. Bioassay methods using Candida pseudotropicalis as a test organism were the first techniques used for the determination of fluconazole in body fluids. Gas chromatographic and high performance liquid chromatographic methods were later developed with better accuracy and sensitivity. Prediction of efficacious concentrations in patients from the minimum inhibitory concentrations in vitro seems to be uncertain because of low efficacy of the drug on some yeasts in vitro compared with efficacy in vivo in animal models. Oral forms (capsule and solution) are quickly absorbed and bioavailability is nearly complete (about 90%). Plasma protein binding is low (11 to 12%) and fluconazole circulates as active drug. Distribution is extensive throughout the tissues and allows the treatment of a variety of systemic fungal infections. The average elimination half-life (t1/2) of 31.6 +/- 4.9h is long, with a minimum of 6 days needed to reach steady-state; thus, a loading dose (equal to double the maintenance dose) is recommended. The metabolism of fluconazole is not qualitatively or quantitatively significant. The main route of elimination is renal. The mean +/- SD (calculated from published data) total and renal clearance values are 19.5 +/- 4.7 and 14.7 +/- 3.7 ml/min (1.17 +/- 0.28 and 0.88 +/- 0.22 L/h), respectively. Concentrations of fluconazole in blood after administration of single doses correlated well with the administered dose. There was very little interassay variation between the data reported in literature. Concentrations in blood after multiple doses also exhibit little variation and the accumulation factor was between 2.1 and 2.8. Fluconazole was found in many body fluids, especially in cerebrospinal fluid and dialysis fluid, allowing the treatment of systemic fungal infections such as coccidioidal meningitis and fungal peritonitis. Concentrations of 1 to 3 mg/L and 20 mg/L are the extreme values expected in clinical practice. In renal insufficiency the fluconazole t1/2 is longer, requiring dosage adjustment in relation to creatinine clearance. In continuous ambulatory peritoneal dialysis a 150mg dose in a 2L dialysis solution every 2 days has been proposed. In haemodialysis, a dose of 100 or 200mg should be given at the end of each dialysis session. Neither old age nor irradiation affect fluconazole pharmacokinetics, but the t1/2 was shorter in children.(ABSTRACT TRUNCATED AT 400 WORDS)

Synthesis and regional rat brain distribution of [11C]MDL 72222: a 5HT3 receptor antagonist

MDL 72222, an antagonist of 5HT3 receptors, was labeled with a specific radioactivity of 340-400 mCi/mumol by alkylation of the nor-precursor with [11C]CH3I. The yield of the synthesis, starting from [11C]methyliodide to the purified product and corrected for decay, was good approximately 70-75%. After i.v. injection, [11C]MDL 72222 diffuses readily in the central nervous system but is not detected as metabolites in brain and blood, during 1 h study carried out in rats. The time course and distribution of [11C]MDL 72222 was assessed in various organs (liver, lung, kidney, heart, whole brain) and in blood; the organ uptake was rapid and large; the highest accumulation was found in the lung. The regional brain distribution shows initial uptake and subsequent retention of tracer in favor of the cerebral cortex. The level of brain radioactivity was not reduced by pretreatment with a 1000-fold excess of unlabeled MDL 72222. These results suggest that [11]MDL 72222 is of limited interest for 5HT3 receptor binding studies in brain in vivo, presumably mainly because of large non-specific binding.

Serum digoxin levels related to plasma propafenone levels during concomitant treatment

Nine patients with supraventricular rhythm disorders were treated during 5-day periods with different oral doses (300, 450, 600, and 900 mg daily) of propafenone concomitantly to long-term digoxin treatment. A poor correlation (r = .398; P less than .05) was obtained when the difference between the mean digoxin serum level (calculated with the Cmin data determined each of the 5 days) observed during a given propafenone dose and the mean digoxin serum level observed before propafenone treatment, was correlated with the dose of propafenone; but an evident correlation (r = .778; P less than .01) was found when the difference in digoxin level was correlated with the plasma propafenone concentration. The propafenone effect of increasing digoxin blood levels was thus concluded to be poorly dose dependent but strongly concentration dependent. The association of propafenone to a long-term digoxin treatment can be considered with a low risk of toxicity when plasma propafenone concentration does not exceed about 1000 ng/mL. Propafenone plasma levels are unpredictable in view of their wide interindividual variation for a given dose, so their measurement is advised to detect high levels and consequently to prevent a rise in digoxin serum concentrations with the possibility of toxicity. In clinical practice, when propafenone concentration determinations are not readily available, digoxin serum levels at least have to be carefully monitored.

Plasma pharmacokinetics and metabolism of the benzodiazepine antagonist [11C] Ro 15-1788 (flumazenil) in baboon and human during positron emission tomography studies

Flumazenil is a specific antagonist of the central benzodiazepine receptor (CBZR). Labelled with 11C, this compound is the reference radioligand for positron emission tomography (PET) study of the CBZR in humans and primates. The time-course of [11C]-flumazenil radioactivity and its main acid metabolite [11C] Ro 15-3890 were reconstructed from the time-course of total radioactivity in plasma after administration with high or low SRA in primates and humans, applying an extraction procedure validated by TLC. The measured pharmacokinetics of [11C]-flumazenil (T1/2 beta = 45.1 +/- 12.3 min, T1/2 alpha = 1.5 +/- 1.5 min; K = 0.14 +/- 0.14 min-1; Vd area = 44.0 +/- 17.0 l; Clp = 40.0 +/- 8.5 l/h) exhibited a very rapid distribution phase followed by fast elimination, with a large volume of distribution; these results were confirmed by HPLC determinations and agree with previously published data on unlabelled flumazenil. Pharmacokinetics of [11C] Ro 15-3890 acid metabolite show that high drug concentrations in the blood are promptly achieved (kf = 0.13 +/- 0.004 min-1), with a very rapid elimination half-life (T1/2m = 4.47 +/- 1.31 min) comparable to that of [11C]-flumazenil. The percentage metabolization of parent compound to the acid [11C] Ro 15-3890 was constant from the 15th minute and was significantly higher in man compared to the monkey. This percentage was increased by prior eating. The other putative metabolites, i.e. labelled [11C] Ro 15-4965 and unlabelled Ro 15-5528, were never observed at detectable concentrations with TLC and HPLC in rabbit, baboon and human blood samples. This pharmacokinetic study of plasma flumazenil may be useful to implement a dynamic method of CBZR quantification using PET and for analysis of pharmacokinetics in brain tissue.

Determination of zolpidem and zopiclone in serum by capillary column gas chromatography

A gas chromatographic method using a short, high-resolution capillary column connected to a specific thermoionic detector and requiring a simple and short extraction step without evaporation was developed for the rapid and precise determination of two new hypnotics, zolpidem and zopiclone, in serum at concentrations greater than 5 ng/mL. The assay was linear between 5 and 200 ng/mL, with coefficients of intra- and interassay variation less than 5% for both. The method was validated and then used to analyze zolpidem serum concentrations in nine rabbits after oral administration of 0.5 mg/kg and zopiclone serum concentrations in six patients treated orally with a 7.5-g dose.

A comparison of methods for the separation of [11C]Ro 15-1788 (flumazenil) from its metabolites in the blood of rabbits, baboons and humans

The determination of the percentage of unchanged [11C]Ro 15-1788 with respect to total radioactivity, essential for the pharmacokinetic exploitation of data of blood radioactivity decrease obtained in PET studies, may be carried out with equal results using either an extraction procedure or a TLC method. The analysis of blood samples of various sources (rabbits, baboons, healthy volunteers and anxious patients) and the use of an automatic linear scanner to quantify the radioactive distribution on the TLC plates lead to the conclusion that only [11C]Ro 15-1788 and its acid metabolite [11C]Ro 15-3890 and no other radioactive compound are present in blood at detectable concentration.

Pharmacokinetics of fluconazole in patients undergoing continuous ambulatory peritoneal dialysis

The pharmacokinetics of fluconazole given orally (100 mg) or intraperitoneally (50 and 150 mg) were determined in 15 patients with chronic renal failure who were undergoing continuous ambulatory peritoneal dialysis. The half-life (72 to 85 hours) was intermediate between values obtained in healthy volunteers and in patients with renal insufficiency studied during an interhaemodialysis period. The peritoneal clearance, 0.26 to 0.33 L/h, led to an 18% recovery of administered drug in the dialysates after 48 hours. The peritoneal absorption was slow (time to peak plasma concentration 7 hours) but the peritoneal bioavailability was excellent at 87 +/- 5%. The mean concentrations of fluconazole up to 24 hours were 770 and 1900 micrograms/L after single intraperitoneal doses of 50 and 150 mg, respectively. The volume of distribution (40 to 60 L) did not differ from that determined in patients with normal renal function. In the case of fungal peritonitis essentially attributed to Candida spp., a 6-hour intraperitoneal infusion of fluconazole 150 mg every 2 days appears to be a good regimen to rapidly exceed minimum inhibitory concentrations and treat infection without risk of systemic dissemination of fungi or toxicity.

Clinical pharmacokinetics after repeated intrapleural bupivacaine administration

Patients (n = 14) who underwent thoracotomy during surgery of the oesophagus for cancer received an initial intrapleural dose of 10 ml bupivacaine hydrochloride 2.5 mg/ml followed by repeated administration every 8 hours from the first to the fourth postoperative day. The mean (+/- SD) peak plasma drug concentration (Cmax) [352 +/- 120 micrograms/L], time to peak (tmax) [0.83 +/- 0.51 h], and first-order absorption rate constant (ka) [5.46 +/- 4.95 h-1] after the twelfth dose were significantly different from the Cmax (206 +/- 81 micrograms/L), tmax (1.8 +/- 1.2h), and ka (1.8 +/- 1.47 h-1) determined after the first dose. Half-life (3.5 +/- 2.2h) and mean concentration (204 +/- 105 micrograms/L) were not significantly different on the fourth day from those on the first (4.1 +/- 2.6h and 142 +/- 71 micrograms/L, respectively). No sharp peak corresponding to systemic toxicity and no accumulation could be expected with these low doses, administered at short intervals and providing good pain relief in this surgical series.

Pharmacokinetics of piperacillin in patients on peritoneal dialysis with and without peritonitis

The pharmacokinetics of piperacillin given intravenously (1 or 2 g) to nine patients with chronic renal failure and undergoing continuous ambulatory peritoneal dialysis was intermediate between values obtained in healthy volunteers and in patients with renal insufficiency studied between dialyses: half-life, 2.4 h; total clearance, 100 mL/min; urinary or peritoneal clearance, 3 mL/min. The intraperitoneal administration of piperacillin in dialysis fluid (400 mg or 1 g to five patients) increased the half-life (6 to 7 h) and decreased the volume of distribution of about two thirds. In both instances, the area under the curve was well correlated with dosage. The absorption of piperacillin by an inflamed peritoneum in eight patients suffering from peritonitis and treated with 400 mg, 1 g, or 2 g, was increased and returned to normal concurrently with care. Consequently, the recommended dosage is intravenous administration of 2 g of piperacillin every 8 h or intraperitoneal administration of 1 g every 6 h in the dialysate. With such conditions, serum concentrations greater than minimal inhibitory concentrations and sufficient to avoid dissemination of piperacillin-susceptible organisms without risk of accumulation are obtained.

Substantial rise in sparteine metabolic ratio during haloperidol treatment

A sparteine test was carried out in 14 patients suffering from acute schizophrenic psychoses before and 1-2 times during oral haloperidol treatment in doses of 10-40 mg day-1. In patients classified as extensive metabolisers (sparteine MR less than 20 before treatment), haloperidol treatment resulted in a rise in sparteine MR that correlated with the serum-haloperidol concentration both within and between patients. At the highest serum haloperidol concentrations (60-80 nM) an increase in sparteine MR by a factor 15-50 was seen, but no patients were transformed into phenotypically poor metabolisers. The steady state concentration of haloperidol on the initial standard dose of 10 mg day-1 was the same in one patient classified as a sparteine poor metaboliser (MR = 112) as in eleven patients classified as extensive metabolisers (MR:0.22-1.47).

Determination of fluconazole in biological fluids by capillary column gas chromatography with a nitrogen detector

Fluconazole concentrations in biological fluids were determined by high-performance gas chromatography. A simple extraction procedure with chloroform, under basic conditions and after the addition of UK-47,265 as the internal standard and with no evaporation stage, was carried out prior to analysis. A solid injector and a 15-m capillary column, coated with a nonpolar phase and connected to a nitrogen-selective detector that afforded an excellent selectivity and sensitivity, constituted the gas chromatographic system. The duration of each analysis was less than 4 min and the minimum detectable serum concentration was 50 ng/mL. In five patients undergoing chronic peritoneal dialysis, the mean serum concentrations +/- SD at 1, 6, and 48 h after the intraperitoneal administration of a single dose of fluconazole were, respectively, 325 +/- 75, 928 +/- 159, and 607 +/- 80 ng/mL.

[Pharmacokinetics of piperacillin during continuous ambulatory peritoneal dialysis]

We studied the kinetics of piperacillin in patients under continuous ambulatory peritoneal dialysis. Piperacillin 2 g was injected intravenously in 6 patients whereas 1 g was given intraperitoneally either a single dose in 3 patients without infection or the same dose every six-hours in 4 patients with peritonitis. Piperacillin was assayed by HPLC. After intravenous administration, the mean plasma piperacillin concentration was 3.1 +/- 5.6 mg/l at 12 h, the mean plasma t1/2 at 2.43 +/- 0.84 h, the volume of distribution at 20.4 +/- 6.3 l and the peritoneal clearance at 0.19 +/- 0.04 ml/min. After iterative intraperitoneal administration, serum and dialysate concentrations of piperacillin were above the minimum inhibitory concentration for susceptible pathogens without antibiotic accumulation. Peritoneal absorption was higher during peritonitis (83.4 +/- 4.8%) than without peritonitis (67.8 +/- 8.5%). Piperacillin 2 g IV every 8 hours or 1 g IP every 6 hours seemed to be the appropriate regimen in patients with chronic renal failure on CAPD.

[Pharmacokinetics and pharmacodynamic effects of digoxin in dilated cardiomyopathies. Influence of nicardipine]

Numerous studies have been devoted to the effect of slow calcium channel inhibitors on plasma digoxin concentrations. The principal drugs tested, verapamil and nifedipine, were found to increase significantly plasma digoxin levels mainly by reducing digoxin total clearance. Very few studies on the nicardipine-digoxin interaction have been reported. The dual purpose of the present study was to evaluate the influence of orally administered nicardipine on plasma digoxin concentrations over 24 hours and to measure possible variations in the pharmacodynamic effects of digoxin in 9 patients with chronic congestive heart failure. The pharmacodynamic assessment involved simple and cross-sectional echocardiography, systolic time interval measurements and cardiac catheterization. In these patients under chronic digoxin treatment, oral nicardipine had little effect on plasma digoxin concentrations which increased but not significantly; no sign of digitalis toxicity was observed. Nicardipine improved left ventricular function and myocardial contractility by reducing after-load, the nicardipine-induced peripheral vasodilatation tending to counteract the digoxin-induced vasoconstriction.

Treatment of caffeine intoxication by exchange transfusion in a newborn

The symptoms of acute poisoning after accidental administration of ten times the usually prescribed dosage of caffeine in a premature infant included the following neurological signs: incessant tremors, hypertonia, continuous opisthotonos posture, whining and crying and digestive disturbances. The very high serum caffeine levels, 160 mg/l, determined 66 hours after the first administration was confirmed by the very high cerebrospinal fluid caffeine concentration 115 mg/l. Two exchange transfusions performed at an interval of 16 hours produced a large decrease in serum caffeine levels of approximately 40 mg/l each time, and a similar decrease in the cerebrospinal fluid concentration. The clinical status of the infant improved very rapidly and the child's psychomotor development was normal at 3 months of age.

Clinical pharmacokinetics of ketoprofen after single intravenous administration as a bolus or infusion

The pharmacokinetics of ketoprofen were evaluated in 29 patients suffering from acute renal colic following a single intravenous administration as a bolus or short infusion (1.5 and 2 hours), and after a loading dose and a 24-hour infusion. Serum concentrations of ketoprofen were measured by high pressure liquid chromatography. The mean (+/- SD) values of clinical parameters were as follows: distribution half-life = 0.34 +/- 0.19 h; elimination half-life = 2.05 +/- 0.58 h; kel = 0.968 +/- 0.282 h-1; k21 = 0.943 +/- 0.425 h-1; k12 = 1.004 +/- 0.708 h-1; volume of central compartment = 5.58 +/- 1.67L; volume of tissue compartment = 5.14 +/- 2.12L; plasma clearance = 5.10 +/- 1.14L/h. These results concur with previously published data obtained after oral or intramuscular administration. According to clinical observations, administration of a ketoprofen bolus suppressed pain within 5 to 30 minutes; the administration of a loading dose and a 24-hour infusion is almost never followed by a recurrence of pain, and this regimen was proposed as the dosage schedule of ketoprofen to treat renal colic.

Spiramycin has no effect on serum theophylline in asthmatic patients

Fifteen asthmatic patients receiving a sustained-release theophylline preparation were also treated with spiramycin for at least 5 days. The macrolide antibiotic had no significant effect on the steady-state theophylline concentration, unlike erythromycin and troleandomycin, which belong to the same class of antibiotics. The latter two drugs have different chemical structures and decrease theophylline clearance. Accordingly, spiramycin comedication does not require special serum level drug monitoring or adjustment of the dose of theophylline.

Prilocaine in arthroscopy: clinical pharmacokinetics and rational use

Prilocaine pharmacokinetics were determined in 60 patients receiving the drug by two different routes of administration (intra-articular and subcutaneous) during arthroscopy under local anesthesia with controlled pressure irrigation. Resorption of prilocaine by subcutaneous tissues was slow and did not lead to high serum levels. On the contrary, prilocaine resorption by the synovium was fast and induced a sharp serum peak (265.8 +/- 163.5 ng/ml) in the hour after the end of the examination. The drug was completely eliminated from the blood after 24 hours, as the prilocaine t1/2 is about 5 hours. The first procedure was perfected to reduce the risk of methemoglobinemia, which occurred in four of 105 patients. Applied pressure was lowered to 100 mm Hg to prevent the escape of anesthetic solution into the soft tissue of the leg, the prilocaine concentration was reduced to 1 gm/L, and the arthroscope was only set up after a delay to allow the intra-articular anesthetic effect of prilocaine to become established. So far, 200 arthroscopies have been performed with this improved protocol without any problem.

Liquid chromatographic determination of noxytiolin and 1-methyl-2-thiourea in serum: application to pharmacokinetic studies in rabbits and humans

A high-performance liquid chromatographic method is described which determines noxytiolin and 1-methyl-2-thiourea concentrations in serum. Valid determination requires immediate ultracentrifugation of blood samples, rapid serum freezing, and injection into the chromatograph within 6 h. A number of pharmacokinetic parameters were calculated from serum concentration data in rabbits and humans. An unknown metabolite was detected in both species but its structure was not identified.

Monitoring serum bupivacaïne levels during arthroscopy

Arthroscopy was carried out after subcutaneous injection of lignocaïne to produce local anaesthesia, using controlled pressure-irrigation with bupivacaïne, followed by final rinsing with an isotonic solution. This procedure, which was painless for the patient and had no systemic toxic effects, gave very good distension of the joint and clear visualization of its structure. A sharp peak in the serum bupivacaïne level (Cmax: 76.2 ng/ml) was observed only 5 min after the start of the irrigation, which was attributed to synovial resorption. This was followed by a slight increase in blood concentration 4 to 5 h after the end of the arthroscopy, probably as a result of absorption by the peripheral soft tissues. Bupivacaïne concentrations never exceeded 350 ng/ml (much lower than the toxic level). The drug persisted in blood for 36 to 48 h (terminal half-life 12.1 h).

Serum level monitoring and therapeutic effect of haloperidol in schizophrenic patients

Haloperidol serum concentrations were determined after IM or oral treatment in 15 schizophrenic patients. No correlation was found between drug levels and therapeutic effect. However, a good relationship was found between the half-life calculated after the first IM injection and the BPRS decrease after 3 weeks. Therefore a serum level study to the first day may forecast the therapeutic response.

Wall-coated open tubular column coupled with nitrogen-selective detector for routine GLC determination of diazepam, meprobamate, phenylbutazone, and thioridazine in serum

The selectivity and sensitivity provided by a wall-coated open tubular column coupled with a nitrogen-selective detector allowed rapid, accurate determination of diazepam, meprobamate, phenylbutazone, and thioridazine in serum in the same chromatographic system using 100--200 microliters of sample.

A practical proposal for arginine-vasopressin radioimmunoassay

This work proposes the use of (a) a commercially available homologous system AVP antibody-AVP (Arginine Vasopressin) standard and (b) new acquisitions for the improvement of sensitivity for AVP radioimmunoassay by separate or simultaneous use of two-phase sequential incubation and epsilon-aminocaproic acid (EACA). The antiserum used in the system described is very specific since none even cross-reacted with lysine vasopressin (LVP) and has an apparent affinity constant (K) of 0.909 +/- 0.047 X 10(12) l/mol. This is sufficiently high to detect 0.5 +/- 0.2 pg/tube, which is theoretically expected of biological AVP. The total assay time is less than 48 h.