KIMS, CEDIA, and HS-CEDIA immunoassays are inadequately sensitive for detection of benzodiazepines in urine from patients treated for chronic pain

BACKGROUND

Patients treated for chronic pain may frequently undergo urine drug testing to monitor medication compliance and detect undisclosed prescribed or illicit drug use. Due to the increasing use and abuse of benzodiazepines, this class of medications is often included in drug screening panels. However, immunoassay-based methods lack the requisite sensitivity for detecting benzodiazepine use in this population primarily due to their poor cross-reactivity with several major urinary benzodiazepine metabolites. A High Sensitivity Cloned Enzyme Donor Immunoassay (HS-CEDIA), in which beta-glucuronidase is added to the reagent, has been shown to perform better than traditional assays, but its performance in patients treated for chronic pain is not well characterized.

OBJECTIVES

To determine the diagnostic accuracy of HS-CEDIA, as compared to the Cloned Enzyme Donor Immunoassay (CEDIA) and Kinetic Interaction of Microparticles in Solution (KIMS) screening immunoassays and liquid chromatography-tandem mass spectrometry (LC-MS/MS), for monitoring benzodiazepine use in patients treated for chronic pain.

STUDY DESIGN

A study of the diagnostic accuracy of urine benzodiazepine immunoassays.

SETTING

The study was conducted at an academic tertiary care hospital with a clinical laboratory that performs urine drug testing for monitoring medication compliance in pain management.

METHODS

A total of 299 urine specimens from patients treated for chronic pain were screened for the presence of benzodiazepines using the HS-CEDIA, CEDIA, and KIMS assays. The sensitivity and specificity of the screening assays were determined using the LC-MS/MS results as the reference method.

RESULTS

Of the 299 urine specimens tested, 141 (47%) confirmed positive for one or more of the benzodiazepines/metabolites by LC-MS/MS. All 3 screens were 100% specific with no false-positive results. The CEDIA and KIMS sensitivities were 55% (78/141) and 47% (66/141), respectively. Despite the relatively higher sensitivity of the HS-CEDIA screening assay (78%; 110/141), primarily due to increased detection of lorazepam, it still missed 22% (31/141) of benzodiazepine-positive urines. The KIMS, CEDIA, and HS-CEDIA assays yielded accuracies of 75%, 79%, and 90%, respectively, in comparison with LC-MS/MS.

LIMITATIONS

This study was limited by its single-site location and the modest size of the urine samples utilized.

CONCLUSIONS

While the HS-CEDIA provides higher sensitivity than the KIMS and CEDIA assays, it still missed an unacceptably high percentage of benzodiazepine-positive samples from patients treated for chronic pain. LC-MS/MS quantification with enzymatic sample pretreatment offers superior sensitivity and specificity for monitoring benzodiazepines in patients treated for chronic pain.

Myalgic encephalomyelitis: International Consensus Criteria

The label 'chronic fatigue syndrome' (CFS) has persisted for many years because of the lack of knowledge of the aetiological agents and the disease process. In view of more recent research and clinical experience that strongly point to widespread inflammation and multisystemic neuropathology, it is more appropriate and correct to use the term 'myalgic encephalomyelitis' (ME) because it indicates an underlying pathophysiology. It is also consistent with the neurological classification of ME in the World Health Organization's International Classification of Diseases (ICD G93.3). Consequently, an International Consensus Panel consisting of clinicians, researchers, teaching faculty and an independent patient advocate was formed with the purpose of developing criteria based on current knowledge. Thirteen countries and a wide range of specialties were represented. Collectively, members have approximately 400 years of both clinical and teaching experience, authored hundreds of peer-reviewed publications, diagnosed or treated approximately 50 000 patients with ME, and several members coauthored previous criteria. The expertise and experience of the panel members as well as PubMed and other medical sources were utilized in a progression of suggestions/drafts/reviews/revisions. The authors, free of any sponsoring organization, achieved 100% consensus through a Delphi-type process. The scope of this paper is limited to criteria of ME and their application. Accordingly, the criteria reflect the complex symptomatology. Operational notes enhance clarity and specificity by providing guidance in the expression and interpretation of symptoms. Clinical and research application guidelines promote optimal recognition of ME by primary physicians and other healthcare providers, improve the consistency of diagnoses in adult and paediatric patients internationally and facilitate clearer identification of patients for research studies.

Pharmacokinetics and pharmacodynamics of recombinant human interferon-beta in healthy male volunteers

The pharmacokinetics and pharmacodynamics of recombinant human interferon-beta (rHuIFN-beta 1a) were assessed following administration to 12 healthy male volunteers. Each subject received, in a double-blind, balanced, random-order, crossover sequence, single doses of 6 MIU of rHuIFN-beta 1a (Rebif) i.v., i.m., and s.c. or matching placebo on four occasions separated by washout periods of 1 week. Blood samples were collected at preset times for the measurement of serum IFN-beta levels and of intracellular 2'-5'-oligoadenylate synthetase levels. Blood pressure, sitting heart rate, respiratory rate, oral body temperature, and tolerance were monitored regularly. All administrations of rHuIFN-beta 1a were well tolerated, although about half of the subjects had a flu-like syndrome, as expected. After i.v. bolus injection, the pharmacokinetics of rHuIFN-beta 1a were well described by a classic two-compartment model. Mean total clearance of rHuIFN-beta 1a was about 100 L.h-1. The distribution half-life was 5 min, and the terminal half-life was approximately 5 h. After i.m. or s.c. injection, serum IFN-beta profiles were rather flat, and about one sixth of the administered dose was available systemically. Extent and duration of clinical and biologic effects were independent of the route of administration and of the IFN-beta serum levels. Biologic pharmacodynamic effects persisted even when IFN-beta serum levels had returned to baseline and were still significantly elevated 3 days after a single dose. Because of the independence of the extent and duration of clinical and biologic pharmacodynamic effects from the route of administration and from the IFN-beta serum levels, the s.c route of administration is preferred in indications in which primarily an immunomodulatory action is sought. Predominantly antiviral and antiproliferative activity is enhanced by the i.v. route to provide adequate drug levels at the site of pathology, although its application is limited on practical grounds.

The effect of age on the pharmacokinetics of pentisomide

The effects of age on the pharmacokinetics of pentisomide (CM7857), an orally effective antiarrhythmic agent, were studied in two groups of volunteers. Sixteen young volunteers (mean age 26.4 years) and 10 elderly volunteers (mean age 67.8 years) received a single 200 mg oral dose of pentisomide. Mean AUC was larger and terminal elimination half-life longer in the elderly subjects, due to a decrease in total plasma clearance of pentisomide in the elderly. This decrease was due to a reduction in renal clearance of the drug which was paralleled by a significantly lower creatinine clearance in the elderly subjects. Dosage reduction, or a reduced frequency of dosing of pentisomide would be necessary in the elderly or those with impaired renal function.

Pharmacokinetics of the anti-inflammatory drug ximoprofen in healthy young and elderly subjects: comparison with elderly rheumatic patients

The pharmacokinetics of ximoprofen were studied in young and elderly subjects after single and repeated doses up to 30 mg. In healthy elderly subjects (30 mg dose), a mean peak plasma drug concentration of 1.78 micrograms ml-1 +/- 0.83 s.d. occurred at a mean time of 1.95 h +/- 1.40 s.d. and, thereafter, concentrations declined monoexponentially with a mean half-life of 3.8 h +/- 1.4 s.d. Comparison of these data with those from younger healthy subjects showed that peak drug concentrations, areas under the curve and half-lives were about two-fold greater in the elderly, these differences probably reflecting a lower systemic drug clearance. Similar results were obtained on comparing data from young healthy subjects and elderly rheumatic patients receiving single and repeated doses of ximoprofen (15 mg twice daily). In patients, the half-life of ximoprofen was 2.5 h +/- 0.7 s.d. Within either group, pharmacokinetic parameters after single or repeated doses were similar: ximoprofen did not accumulate in the plasma of the young or elderly.

Pharmacokinetics of the anti-inflammatory drug ximoprofen in healthy subjects and in disease states

The pharmacokinetics of ximoprofen, a potent new non-steroidal anti-inflammatory agent, has been investigated in normal healthy subjects and in patients with hepatic or renal disease. After intravenous infusion of 22.8 mg to healthy subjects, plasma ximoprofen concentrations declined in a polyexponential manner with a terminal phase half-life of 1.9 h. The systemic clearance of ximoprofen was 115 ml.min-1 and the volumes of distribution were 18.01 Vz and 13.81 Vss. Ximoprofen was 80-90% bound to plasma proteins. The systemic availabilities (f) of orally and rectally administered doses of 30 mg of ximoprofen were 98% and 56% respectively and, in the case of the rectal dose, absorption appeared to be prolonged leading to "flip-flop" kinetics. After single oral doses of 30 mg of ximoprofen to patients with hepatic disease, half-life (2.2 h), peak plasma concentrations (1.55 micrograms.ml-1 cf 1.04 micrograms.ml-1 in healthy subjects) and areas under the curve (6.12 micrograms.h.ml-1 cf 3.54 micrograms.h.ml-1 in healthy subjects) were significantly different from those in healthy subjects. After single oral doses of 30 mg of ximoprofen to patients with renal disease, pharmacokinetic parameters of half-life (4.0 h), mean residence time (6.0 h) and area under the curve (9.2 micrograms.h.ml-1) were significantly different from those in healthy subjects. There were no significant differences in pharmacokinetic parameters between patients having differing degrees of renal disease. These data nevertheless suggest that accumulation of ximoprofen in hepatic or renal disease would be of slight or negligible clinical relevance and that no alteration of the dose regimen (up to 15 mg twice daily) may be required when ximoprofen is administered in these disease states.

Pharmacokinetics of falipamil after intravenous administration to humans

Falipamil (2-[3-[3-(3,4-dimethoxyphenetylmethylamino]propyl]-5,6- dimethoxyphthalamidine; 1) is a new specific bradycardic agent for the treatment of sinus tachycardia. Pharmacokinetics of falipamil in humans (n = 6) was determined in plasma and urine after iv administration of 100 mg (1.85 MBq) per person of 14C-labeled drug by liquid scintillation counting and by a specific, sensitive reversed-phase totally automated HPLC system with fluorimetric detection. Recovery of total radioactivity was 91.8 +/- 3.7%, with 68.2 +/- 4.3% in urine and 23.6 +/- 2.5% in the feces. The majority of radioactivity was excreted within 24 to 48 h. The parent drug, falipamil (1), and its N-desmethyl-metabolite (2), which is approximately 100 times less active than 1, contributed 14.1 +/- 1.6 and 4.5 +/- 0.7%, respectively, of the dose to urinary excretion. Plasma protein binding of 1 and 2 was 87.9 +/- 1.2 (concentration range: 2000-8000 ng/mL) and 89.7 +/- 0.5% (concentration range: 62.5-1000 ng/mL), respectively. Plasma concentrations of 1 peaked at 2 min at 724 +/- 173 ng/mL, declined biphasically, and were fitted to a two-compartment open model. Plasma concentrations of 2 were very low, in all cases ranging from 0 to 35 ng/mL. The dominant terminal half-life (beta-phase) of 1 from plasma was 1.8 +/- 0.6 h (range 1.4-2.9 h), mean residence time was 2.4 +/- 0.4 h, total body clearance was 1108.5 +/- 119 mL/min, and renal clearance was 117 +/- 20 mL/min. All parameters demonstrated very low intersubject variability.

EEG brain mapping in evaluating the time-course of the central action of DUP 996--a new acetylcholine releasing drug

1. In a double-blind, placebo-controlled study the encephalotropic effects of DUP 996, a novel phenylindolinone derivative for Alzheimer's disease enhancing the release of acetylcholine in cholinergic nerve terminals in the brain only when its release is triggered, were studied with special consideration of the pharmacodynamic time-course. 2. Thirteen healthy male volunteers aged 18-40 years received randomized and at weekly intervals, single oral doses of placebo and 30 mg DUP 996. Blood sampling for plasma concentration analysis, EEG recordings and evaluation of pulse, blood pressure and side effects were carried out at 0, 1, 2, 4, 8, 12 and 24 h. 3. Computer-assisted spectral analysis of the EEG and subsequent topographic brain mapping of the drug-induced EEG changes demonstrated significant central effects of DUP 996 suggesting vigilance-improving properties. The findings were characterized mostly by an augmentation of total power as well as by an increase of absolute power in the alpha and alpha-adjacent beta activity. 4. Time-course investigations demonstrated two pharmacodynamic peaks: a first one in the 2nd h and a second one in the 12th h. In detail CNS effects increased up to the 2nd h, showed a drop in the 4th h, increased again thereafter to peak in the 12th h. Even in the 24th h there were significant differences between DUP 996 and placebo. The latter suggests an indirect effect and/or an active metabolite, as the parent drug is rapidly absorbed and has a rather short plasma half-life between 1-3 h. 5. DUP 996-induced EEG-changes over time were most pronounced over temporo-occipital, temporo-frontal, parietal and frontal regions, e.g. over brain areas afflicted most by Alzheimer's disease. 6. Evaluation of vital signs, laboratory findings and ECG as well as adverse effects showed a very good tolerability of DUP 996.

Tanakan inhibits platelet-activating-factor-induced platelet aggregation in healthy male volunteers

An open study to investigate the PAF-acether antagonist activity of Tanakan in healthy male volunteers examined the effect of a single 15-ml oral dose on ex vivo platelet aggregation induced by adrenaline, adenosine diphosphate (ADP), collagen or PAF-acether. Aggregometry was performed on platelet-rich plasma samples from blood taken 1 h before dosing with Tanakan and 2, 4 and 8 h after intake of Tanakan. Following dosing with Tanakan there was a reduction in platelet aggregation at all doses of PAF, with 1 microM ADP and adrenaline, the most significant decreases occurred with 75 nM PAF-acether 4 h after intake (p less than 0.05) and 300 nM PAF-acether 4 h (p less than 0.01) and 8 after intake (p less than 0.05). There were no concomitant changes in coagulation, skin bleeding time, haematological and biochemical laboratory tests, blood pressure or pulse. The results provide a possible explanation for the clinical efficacy of Tanakan in the treatment of peripheral vascular disease; they also confirm that a single oral dose of 15 ml Tanakan is well tolerated.

Tolerance and nasal histopathologic effects of long-term, low-dose intranasal recombinant interferon alpha-2A (Roferon-A)

The dose-related tolerance and histopathologic effects of intranasal recombinant interferon alpha-2a (rIFN-alpha 2a) were determined in a blind study in which healthy subjects were randomized to receive sprays of interferon (IFN) (3 or 6 MU/day) or placebo for 28 days. Adverse nasal symptoms (bleeding, obstruction, irritation) tended to occur more often in the IFN 6 MU/day group. Blind analysis of biopsy samples collected before and after IFN treatment revealed that both IFN groups had significant histologic changes, most commonly an increased degree of lymphocytic infiltration in the subepithelium and underlying glandular zones. Changes developed in 61% of 18 recipients of IFN 6 MU/day, 37% of 19 recipients of IFN 3 MU/day, and 6% of 18 placebo recipients. Serum antibodies to rIFN-alpha 2a detectable by EIA were found in 4 recipients of IFN 3 MU/day and 2 recipients of IFN 6 MU/day, one-third of whom were positive by neutralization bioassay. The findings would predict that these rIFN-alpha 2a dosages would be associated with an excess of adverse side effects during long-term use in healthy adults.

Metabolic fate of the thrombolytic agent benzarone in man: comparison with the rat and dog

1. The metabolic fate of 14C-benzarone in the rat and dog has been compared to that in human subjects. An oral dose was well-absorbed in all three species. However, the 14C excretion patterns differed: humans (100 mg) excreted means of 73 and 19% dose in the urine and faeces respectively, whereas the rat (2 mg/kg) and dog (0.5 mg/kg) excreted greater than 80% in the faeces, mostly during the first 48 h. 2. Much of the faecal 14C was attributable to 14C excreted in the bile which amounted to 59% in the 7 h bile collected from an intravenously dosed dog, and a mean of 72% in the 24 h bile of orally dosed rats. Enterohepatic circulation of 14C was demonstrated in rats. 3. Total 14C in human plasma reached peak concentrations between 1-2 h and declined relatively rapidly, to about 10% of this value within 24 h. Unchanged benzarone was not detected in plasma (less than 25 ng/ml), even after a 400 mg dose, but conjugated benzarone was--accounting for about 10% of the peak concentration of 14C. In the dog, by contrast, conjugated benzarone accounted for about 50% of the peak concentration of 14C of 0.96 microgram equiv./ml at 1 h. The extent of binding of benzarone to human plasma proteins (greater than 99%; in vitro was slightly greater than that (greater than 96%) of total 14C (ex vivo, representing metabolites). 4. Examination of metabolite profiles by h.p.l.c. suggested that in the rat and dog, at least 70% absorbed dose was eliminated by direct conjugation, whereas in humans at least 70% was hydroxylated before conjugation, mainly with glucuronic acid. Hydroxylation occurred in the benzofuran ring and/or the ethyl side-chain. The principal urinary metabolite in humans was the conjugate(s) of the 1-hydroxylated ethyl side-chain derivative (mean 26% dose).

Pharmacokinetics and metabolism of 14C-tinidazole in humans

Following intravenous infusion of 800 mg of 14C-tinidazole during 30 min to two human subjects, a mean of 44% of the dose was excreted in urine during the first 24 h, increasing to 63% of the dose during five days: 12% of the dose was excreted in the faeces, indicating the possible involvement of biliary excretion and other secretory processes in the disposition of tinidazole. At 6 min after the end of the infusion, the mean plasma tinidazole concentration was 12 mg/l. Tinidazole was a major component in 0-120 h urine (about 32% of urinary 14C): the major metabolite in the 0-12 h urine examined was ethyl 2-(5-hydroxy-2-methyl-4-nitro-1-imidazolyl)ethyl sulphone (about 30% urinary 14C), the product of hydroxylation and nitro-group migration. These compounds were also present in the faeces. A minor urinary metabolite was 2-hydroxymethyltinidazole (about 9% urinary 14C), which was also present in plasma. The mean pharmacokinetic parameters obtained for tinidazole were similar to those reported in the literature; total clearance 51 ml/min, renal clearance 10 ml/min, volume of distribution 501 and half-life 11.6 h.

Pharmacokinetics and bioavailability of the anti-emetic agent bromopride

The pharmacokinetics of bromopride, an anti-emetic agent chemically related to metoclopramide, has been investigated in normal human subjects. After intravenous bolus doses of 10 mg, a one-compartment open model appeared adequate to describe the plasma drug concentration data. The systemic clearance of bromopride was 899 ml min-1 +/- 22 per cent CV, the volume of distribution was 2151 +/- 16 per cent CV, and the elimination half-life was 2.9 h +/- 21 per cent CV. Over a wide drug concentration range of up to 650 ng ml-1, bromopride was only 40 per cent bound to plasma proteins. The systemic availability of orally and intramuscularly administered solution doses of 20 mg of bromopride was 54 per cent and 78 per cent, respectively. Formulation of bromopride as the solid material in capsules delayed absorption but did not affect the extent of drug bioavailability. The pharmacokinetics of bromopride appeared similar to that of metoclopramide. No evidence for non-linear kinetics was found when bromopride was administered orally in the dose range 10-30 mg: after single oral doses of 10, 20, and 30 mg, peak mean plasma drug concentrations were 20 ng ml-1 +/- 32 per cent CV, 38 ng ml-1 +/- 16 per cent CV, and 64 ng ml-1 +/- 23 per cent CV, respectively.

Interaction of antimicrobial agents with human peripheral blood leucocytes: uptake and intracellular localization of certain sulphonamides and trimethoprims

The uptake of sulphamethoxazole, sulphadiazine, sulphamerazine, sulphanilamide, trimethoprim and brodimoprim by human peripheral blood leucocytes, has been investigated. High performance liquid chromatography (HPLC) was used to assay drug concentrations before and after incubation with leucocyte suspensions. Using radiolabelled material the intracellular localization of two of these compounds was also determined. The results indicated that all the investigated drugs were taken up by leucocytes. Differential studies demonstrated that mononuclear cells accumulated higher drug concentrations (0.13-0.55 microgram/10(7) cells), than resting neutrophils (0.02-0.26 microgram/10(7) cells) with the exception of sulphanilamide, which was taken up to a greater extent by neutrophils (0.75 microgram/10(7) cells). During neutrophil phagocytosis intracellular levels of all the drugs except brodimoprim increased from 3 to 130-fold as compared to resting neutrophils. The uptake of 14C-sulphanilamide and 14C-trimethoprim, in neutrophils and mononuclear blood cells, as assessed by measurement of the cell-associated radioactivity, correlated well with that determined by the HPLC procedure. In the intracellular localization studies 14C-sulphanilamide and 14C-trimethoprim exhibited similar distribution profiles. In neutrophils, 35-40% of radiolabelled drug was located in both the microsome and cytosol fractions whereas in peripheral blood mononuclear cells 40-60% was found in the cytosol and 10-20% in the microsome fraction. The results of this study suggest that, following activation, leucocytes may actively transport these drugs and release them locally at sites of infection. The ability of neutrophils to further concentrate the drugs during phagocytosis may result in reduced survival time of some ingested bacteria. These concepts may be important in designing treatment stratagems for intracellular pathogens.

Study of the tolerance and diuretic properties of torasemide following oral or intravenous administration to healthy volunteers

The tolerance and diuretic properties of torasemide after oral or intravenous administration to healthy volunteers were studied. Six groups, each of 6 subjects, were given single rising oral doses ranging from 10 to 100 mg; 8 subjects received ascending i.v. doses on alternate days, ranging from 2.5 to 80 mg. At the highest oral doses investigated (80 mg and 100 mg) a number of volunteers complained of cramps in the knees, calves and feet. These symptoms were generally of short duration. Similar effects were not encountered during the intravenous study. There were no significant changes in ECG. Some significant drug-related changes were encountered in the within-study biochemistry and haematology assessments. Torasemide proved to be a potent diuretic following oral administration at all the doses investigated and following intravenous administration at all doses except 2.5 mg. A linear relationship existed between the urine output and the logarithm of the dose, and both sodium and chloride excretion were linearly correlated with urine volume. The rate of potassium excretion was markedly lower than that of sodium and chloride and was linearly correlated with the logarithm of the urine volume. Torasemide was well tolerated from all perspectives studied. It showed a potent diuretic property, and was equally effective by the oral and intravenous routes.

Effect of celiprolol, a new beta 1-alpha 2 blocker, on the cardiovascular response to exercise

The pharmacodynamics of beta blockade with single oral doses of celiprolol 200 and 400 mg, compared with placebo, atenolol 50 and 100 mg, propranolol 80 and 160 mg, metoprolol 100 and 200 mg, and pindolol 5 and 10 mg, were evaluated in an open, incomplete-block study design employing 11 healthy male volunteers. Each subject received five of the 11 possible treatments at weekly intervals. The maximal rate-pressure product (RPP) induced by standardized treadmill exercise was measured 1, 2, 4, 6, 8, 12, 24, 36, and 48 hours after each treatment. During the course of the exercise test, heart rate and systolic blood pressure were recorded at one-minute intervals for five minutes. The maximal RPP, heart rate, and the maximum change from baseline were calculated for each exercise period. The data were analyzed using absolute reduction and percentage reduction of these parameters. All of the beta blockers tested produced significant decreases (P less than .05) in the exercise RPP, ranging from 16% reduction for celiprolol 200 mg to 47% reduction for propranolol 160 mg at peak response. Celiprolol 400 mg reduced the RPP by 31% at peak effect and did not differ significantly from the other treatments. Celiprolol 400 mg and atenolol 100 mg were the only agents that significantly reduced the RPP 24 hours posttreatment (20.7% and 21.7%, respectively) compared with placebo. Celiprolol 400 mg was the only agent to significantly reduce exercise heart rate 24 hours posttreatment (26.6 beats, P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Metabolism and pharmacokinetics of the dihydropyridine calcium antagonist, ryosidine, in man

The metabolic fate of [14C]ryosidine (ryodipine) has been investigated after oral administration to human subjects (by capsule), and to rats and dogs (in solution). The excretion patterns of 14C were similar for all three species: about 50% dose was excreted in urine, mainly in 24 h, but a proportion was excreted slowly, particularly by humans. Absorption in man appeared to be less than in the animal species, probably as a result of the capsule dosage form used. Mean concentrations of total 14C in human plasma reached a peak value of 0.41 microgram equiv./ml at four hours and declined biphasically thereafter (mean terminal t1/2 = 28 h). Unchanged ryosidine was only detected in plasma from two to six hours (mean t1/2 = 80 min), and never accounted for more than 5% of the plasma 14C. The extent of binding of ryosidine to the plasma proteins (in vitro) was similar (greater than 90%) to that of total 14C (in vivo; mainly metabolites). Less than 0.5% of the dose to human subjects was excreted via the kidneys as unchanged ryosidine, whereas the bulk of the extractable faecal 14C was in the form of unchanged drug and presumably represented unabsorbed material. The principal routes of biotransformation of ryosidine in all three species involved oxidative aromatization of the 1,4-dihydropyridine ring, followed by ester hydrolysis, O-dealkylation, hydroxylation of an alpha-methyl group (and lactonization) and some glucuronidation, although quantitative interspecies differences were apparent.

High-performance liquid chromatographic determination of certain salicylates and their major metabolites in plasma following topical administration of a liniment to healthy subjects

The liniment used is a topical analgesic and anti-inflammatory preparation containing two active constituents, 3-phenylpropylsalicylate and ethyl-5-methoxysalicylate, in solution in isobutyl decanoate. It is known that 3-phenylpropylsalicylate is metabolised to salicylic acid and salicyluric acid and ethyl-5-methoxysalicylate is metabolised to 5-methoxysalicylic acid and gentisic acid. In the present study the separation of the salicylates and their metabolites was carried out on a Waters mu Bondapak C18 column using two different mobile phases, methanol-water (80:20) for the parent drugs and methanol-5% aqueous acetic acid (27:73) for their metabolites. The salicylates and their metabolites were detected by absorption at 310 nm. The limits of detection for parent drugs and metabolites were respectively 0.2 and 0.1 microgram/ml in plasma, using a 1-ml plasma sample and a 20-microliter injection from a reconstituted volume of 250 microliter. Mean percentage coefficients of variation for intra-assay and inter-assay precision were between 3.3 +/- 1.9% to 9.1 +/- 3.7% and 6.8 +/- 2.2% to 15.7 +/- 10.1%, respectively. Linearity, as measured by the correlation coefficient of intra-assay linear regression curves, was better than 0.998 in all cases.

Metabolism of the anti-depressant lortalamine

Humans excreted an oral dose of 5 mg of the anti-depressant lortalamine (radiolabelled with carbon-14) mainly in the urine (98% during 5 days). Plasma 14C concentrations were highest (about 44 ng equiv./ml) between 1.5-3 h when the corresponding concentrations of unchanged drug were about 17 ng/ml. Unchanged drug concentrations appeared to decline with a half-life of about 5 h. Concentrations of 14C then declined rapidly and were below the limits of detection (12 ng equiv./ml) at 24-36 h. Measurement of whole-blood 14C concentrations showed that there was some uptake into the blood cells (about 65% of the peak plasma 14C level). Radioactivity in the urine was mainly associated with unchanged drug and three metabolites. The major metabolite (about 50% urinary 14C) was identified by mass spectrometry as the N-demethylated compound and another metabolite as a keto derivative of lortalamine where oxidation had occurred in the piperidine ring.

The metabolic fate of 11-bromo[15-3H]vincamine in man

During 5 days following a single oral dose of 3H-11-bromovincamine (40 mg) to two human subjects, means of 55% and 27% of the 3H dose were excreted in the urine and faeces respectively, mainly within 24 and 48 h. Mean plasma concentrations of 3H reached a peak (1900 ng equiv./ml) at 1 h after dosing and declined biphasically with half-lives of 5 h and 11 h which were similar to half-lives for urinary excretion of 3H. Parent drug and 11-bromovincaminic acid were the major dose-related components in plasma at 1.5 and 3 h. Mean plasma concentrations of 11-bromovincamine reached a peak (620 ng/ml) at 0.75 h and declined biphasically with half-lives of about 1 h and 5 h. The major urinary metabolite was 11-bromovincaminic acid (31% dose). Also present in urine were 11-bromovincamine (3%), 11-bromoapovincamine (1%) and 2 unknown metabolites (9% and 6%). Similar metabolites were detected in faecal extracts. If inadequately stored in biological samples, 11-bromovincamine could be hydrolysed to 11-bromovincaminic acid and be epimerised to 11-bromo-epivincamine.

Bioequivalence of a sustained-release isosorbide dinitrate formulation at steady-state

Isosorbide 2,5-dinitrate and its pharmacologically active metabolites, isosorbide 2-nitrate and isosorbide 5-nitrate, in plasma accumulated to the predicted steady-state after five consecutive oral doses of sustained-release tablets containing 40 mg isosorbide dinitrate at 12-h intervals and after five consecutive oral doses of reference standard-release tablets containing 20 mg at 6-h intervals to 12 subjects in a crossover study. The comparative bioavailability of isosorbide dinitrate, isosorbide 2-nitrate and isosorbide 5-nitrate from the sustained-release tablet was 110 per cent (p greater than 0.05), 89 per cent (p greater than 0.05), and 89 per cent (p less than 0.05), respectively, of that from the reference standard-release tablet. The isosorbide dinitrate plasma level data were the more variable, as expected for a drug of low systemic availability subject to extensive first-pass elimination. The posterior probability that the true bioavailability of isosorbide dinitrate was included within the usually accepted limits of 80-120 per cent was 0.74, a value which is probably insufficient to justify claims of bioequivalence with the reference formulation in respect of extent of availability. In contrast, the posterior probability that the bioavailability of the metabolites isosorbide 2- and 5-nitrate was included within these limits was 0.90 and 0.98, respectively. On the basis of the mononitrate data, these two formulations may be judged bioequivalent in respect of extent of availability despite a formal statistically significant formulation-related effect in the analysis of variance of the isosorbide 5-nitrate bioavailability data. Claims of bioequivalence of isosorbide dinitrate sustained-release formulations may be more economically justified by analysis of the mononitrate plasma concentrations, although concentrations of the formulated parent dinitrate should also be known.

Sudden death of a volunteer

A volunteer participating in a study of eproxindine, a new antiarrhythmic agent, had a sudden cardiorespiratory arrest and died. Subsequently it became known that he had received a depot injection of flupenthixol on the day before his death; an interaction between these two drugs seems likely. This incident illustrates that it is impossible to guarantee absolute safety in volunteer studies if details of medical history are withheld.

Gas chromatographic determination of mefloquine in human and dog plasma using electron-capture detection

A sensitive and selective gas-liquid chromatographic method for the determination of plasma levels of mefloquine in human and dog plasma is described. The drug and internal standard were extracted from plasma at pH 9.0 into isopropyl acetate. After evaporation of the solvent, the residue was taken up in toluene and derivatised with heptafluorobutyrylimidazole. The derivative was quantified by gas-liquid chromatography on a 3% GC GE-SE30 column with electron-capture detection. The limit of detection for mefloquine in plasma was 10 ng/ml. The mean overall recovery from plasma was 102.7 +/- 3.3%. The method was shown to be specific for mefloquine without any interference from endogenous compounds in plasma or from the drugs pyrimethamine and sulfadoxine (compounds often administered in combination with mefloquine). The assay described was successfully applied to the determination of plasma levels of mefloquine in man and dog following oral and intravenous administration, respectively.

Central effects in man of the novel schistosomicidal benzodiazepine meclonazepam

The novel benzodiazepine derivative, meclonazepam (3-methylclonazepam) has been found to be orally effective at high doses against all stages of schistosomiasis. Animals studies have shown it to have a high therapeutic index and a profile of behavioural activity typical of the benzodiazepines. The effects of single oral doses of meclonazepam, 1, 2 and 4 mg on central arousal, psychomotor performance and subjective mood were studied in two double-blind placebo controlled studies in healthy volunteers. In doses exceeding 1 mg, meclonazepam caused marked dose-related impairment in cognitive and psychomotor functions as well as shifts in mood reflecting sedation and ataxia. These effects were most prominent in the first 3 h after administration, with moderate sedation still present 6 h after the 4 mg dose. The implications of these findings for the use of benzodiazepine agents in the treatment of schistosomiasis are discussed.

Single-dose and steady-state pharmacokinetics of piroxicam in elderly vs young adults

Age-dependent changes in pharmacokinetics are considered a possible factor contributing to a higher risk of side-effects from drug treatment in the elderly. However, very little is known about the kinetics and metabolism of most NSAI agents in geriatric subjects. In a prospective age-comparison study, the single dose and steady-state pharmacokinetics of piroxicam 20 mg once daily were determined in 44 subjects ranging in age from 30 to 80 years. Plasma concentrations, elimination half-life, AUC, and volume of distribution were not influenced by age or sex and were in agreement with previously reported results in young adults. Pharmacokinetic parameters in 18 patients with evidence of mild or moderate renal impairment at study entry were not different from those in patients without impairment. Based on this and other studies, elderly patients receiving the recommended dose of piroxicam are not exposed to undue risk related to pharmacokinetic considerations.

Isosorbide 5-mononitrate kinetics

The kinetics of isosorbide 5-mononitrate (5-ISMN) were studied in 12 healthy subjects after intravenous infusion and oral doses of 20 mg. Kinetic parameters calculated by model-independent methods or by assumption of a one-compartment open model were in good agreement. Mean (+/- SD) systemic clearance of 5-ISMN was 127 +/- 21 ml/min, volume of distribution was 48.5 +/- 6.1 l, t 1/2 was 4.4 +/- 0.5 hr, and mean residence time was 6.2 +/- 0.7 hr. At the end of intravenous infusion of 5-ISMN at a rate of 8 mg/hr for 2.5 hr, mean plasma drug concentrations reached 356 +/- 39 ng/ml. Oral doses of 5-ISMN were essentially completely absorbed (93% +/- 13% systemic availability), and mean peak plasma drug concentrations of 388 +/- 70 ng/ml occurred at 0.83 +/- 0.46 hr. Mean absorption t 1/2 was 19 +/- 12 min. Unlike other vasodilator organic nitrates in clinical use, 5-ISMN is notable for its relatively long t 1/2, essentially complete oral absorption, lack of active metabolites, and low intersubject variability in kinetics.

Isosorbide dinitrate plasma concentrations and bioavailability in human subjects after administration of standard oral and sublingual formulations

The bioavailability of isosorbide dinitrate from formulations containing 5, 10, and 20 mg in tablets and 10 mg in solution for oral use and 5 mg in tablets for sublingual use, has been compared. When adjusted for dose, the peak mean plasma drug concentrations after oral administration were similar (e.g., 9.2 ng/mL after a 10-mg tablet) and about one-half that obtained after sublingual administration. Drug concentrations declined monoexponentially with mean half-lives ranging from 25-36 min. The relative bioavailability of isosorbide dinitrate from the oral formulations was not significantly different (p greater than 0.05) over the dose range studied, whereas the relative bioavailability after sublingual administration was about twice as great (p less than 0.01) as that after oral administration. The plasma drug concentration-time profile after administering the 5-mg sublingual tablet was similar to that obtained after administering orally a solution containing 10 mg, indicating that the latter should be as clinically effective as the former.

Metabolic fact of 14C-isosorbide 5-mononitrate in humans

Single oral doses of 20 mg of the carbon-14 labelled form of the antianginal drug isosorbide 5-mononitrate (5-ISMN, Elantan) were essentially completely absorbed and excreted fairly rapidly in the urine. Means of 24, 52, 78, 93 and 96% dose were excreted during 6, 12, 24, 48 and 120 h, respectively. Concentrations of 14C reached peak levels at about 1-2 h when about 86% of the 14C was associated with the parent drug, 5-ISMN (peak mean level 430 ng/ml), and the remainder mainly with the pharmacologically-inactive denitrated product isosorbide. Because the plasma (and urinary) half-life of isosorbide was longer (about 8-9 h) than that of 5-ISMN (about 4.5 h), the proportions of the former in plasma increased relative to the latter. Concentrations of 14C in whole-blood and plasma were similar, implying that 5-ISMN diffused into blood cells. Concentrations of 5-ISMN in saliva and plasma were almost identical, presumably because of the almost negligible plasma protein binding of the drug (less than 5%). At least five metabolites of 5-ISMN were detected in urine - these were isosorbide (about 37% dose), conjugated material (about 25% dose) presumably mainly 5-ISMN-glucuronide, sorbitol (about 7% dose), the parent drug 5-ISMN (about 2% dose) and two unidentified metabolites (about 7 and 4% dose, respectively). The conjugated material was excreted in the urine relatively more rapidly than the denitrated product, isosorbide.

[Bioavailability of isosorbide-5-mononitrate from delayed-action formulations]

The relative bioavailability of isosorbide-5-mononitrate (IS-5-MN) has been determined after a 3-day period of dosing with 20 mg in standard-release reference tablets and sustained-release capsules at 12-h intervals, 40 mg in sustained-release capsules (Olicard 40 retard) at 24-h intervals and after single oral dose of 60 mg sustained-release capsules (Olicard 60 retard), in a cross-over study with 12 human subjects. Accumulation factors of 1.1-fold or 1.2-fold occurred during administration of 20 mg in standard- or sustained-release tablets and capsules respectively at 12-h intervals, and negligible accumulation of drug occurred after administration of 40 mg in sustained-release capsules at 24-h intervals or was calculated by the superposition principle to occur after doses of 60 mg in sustained-release capsules at 24-h intervals. The mean extent of bioavailability of IS-5-MN from the 20 mg, 40 mg and 60 mg sustained-release capsules was 79%, 67% and 70% respectively, of that from the standard-release reference tablets. The posterior probability that the bioavailability of IS-5-MN was included within the limits 60%-90% of the reference tablets was 97%, 86% and 95% for the 20 mg, 40 mg and 60 mg sustained-release capsules respectively. Means of peak plasma levels of IS-5-MN after administration of the sustained-released capsules were linearly related to the doses administered.(ABSTRACT TRUNCATED AT 250 WORDS)

The metabolism of the anti-inflammatory drug eterylate in rat, dog and man

Oral doses of 14C-eterylate were well absorbed by rat and man and excreted mainly in the urine (94% dose by rat in three days and 91% by man in five days). Oral doses to dogs were excreted in similar proportions in both the urine and faeces, although faecal 14C was probably derived in part, from biliary-excreted material. Peak plasma 14C and drug concn. were generally reached between one and three hours after oral doses. In humans, only two metabolites, salicylic acid and 4-acetamido-phenoxyacetic acid, were detected in plasma. The latter was cleared more rapidly than the former and hence plasma salicyclate concn. reached a peak (10.9 and 19.8 micrograms/ml in Subjects 1 and 2, respectively) and initially declined with a half-life of about two-three hours. Plasma 4-acetamidophenoxyacetic acid concn. reached a peak (4.3, 10.0 micrograms/ml, respectively) and declined with a half-life of about one hour. Tissue concn. of 14C were generally greater in dogs than in rats. Highest conc. occurred at three hours in dogs and at one hour in rats. Apart from those in the liver and kidneys, tissue concn. were lower than those in the corresponding plasma. Unchanged drug was not detected in urine or plasma of any species and was rapidly metabolized in human plasma. The major 14C components in human urine were identified as salicyluric acid and 4-acetamidophenoxyacetic acid; minor metabolites were salicylic acid, gentisic acid and paracetamol. These metabolites were also detected in rat urine albeit in different proportions to those in human urine. Dog urine contained less of these metabolites and a major proportion of the 14C was associated with relatively non-polar components. Although salicylic acid and 4-acetamidophenoxyacetic acid were the only major circulating metabolites in man and rat, dog plasma also contained the non-polar urine metabolites.

Bioavailability of isosorbide dinitrate and its two mononitrate metabolites from sustained-release formulations

Plasma concentrations and bioavailability of isosorbide dinitrate (ISDN) and its active metabolites isosorbide 2-mononitrate (2-ISMN) and isosorbide 5-mononitrate (5-ISMN) from two sustained-release formulations and one standard-release formulation of isosorbide dinitrate were compared. Means of peak drug concentrations of ISDN, 2-ISMN, and 5-ISMN after administration of the 20-mg sustained-release formulation were 5.5, 24.4, and 129.1 ng/ml, respectively, at 3.1, 4.2, and 4.5 h; after the 40-mg sustained-release formulation, they were 10.9, 44.0, and 214.5 ng/ml, respectively, at 4.2, 6.3, and 6.7 h; and after the 20-mg standard formulation, they were 19.1, 34.7, and 159.2 ng/ml, respectively, at 0.5, 1.0, and 1.5 h. As might be expected, peak concentrations and their times of occurrence were statistically significantly different when results from the sustained-release formulation were compared to those from the standard formulation. Plasma drug concentrations were detectable for longer after administration of the sustained-release formulations. The extent of bioavailability of ISDN, 2-ISMN, and 5-ISMN from the three formulations as estimated from the areas under the plasma drug concentration - time curves were not statistically significantly different (p greater than 0.05). The ratios for relative drug bioavailability from the respective formulations were similar whether ISDN, 2-ISMN, or 5-ISMN data were used for calculation. Reasons are discussed for the biphasic decline of plasma ISDN concentrations (half-lives 26 min and 5.1 h) obtained after administration of the standard-release formulation.

Determination of heptaminol in human plasma and urine by high-performance liquid chromatography

Heptaminol was measured in plasma and urine following pre-column derivatisation with o-phthalaldehyde and reversed-phase high-performance liquid chromatography employing fluorescence detection. The limits of detection were sufficient for pharmacokinetic studies of the drug after clinically-used doses. Plasma concentrations of heptaminol reached peak levels (2.19 micrograms/ml) at 0.75 h after single oral doses (0.47 g of heptaminol) and declined with a half-life of 2.1 h (+/- 0.5 S.D.). Heptaminol was well absorbed and excreted rapidly, mainly unchanged in urine, 82% dose (+/- 10 S.D.).

The metabolic fate of the anti-androgenic agent, oxendolone, in man

After intramuscular administration of 16 beta-ethyl-17 beta-hydroxy-4-4-[4-14C]estren-3-one (14C-oxendolone; 300 mg) to 3 human subjects, excretion of 14C was very slow and incomplete despite a 20-day sample collection period. During this time, means of 37% and 21% of the administered 14C were recovered in urine and faeces, respectively, and if excretion continued at the same rate, approximately 90% of the administered 14C would have been excreted during 5-12 weeks. Peak plasma 14C concentrations were reached at 3-6 days after dosing, when they represented 0.2-1.1 micrograms equiv./ml, and declined very slowly thereafter with a half-life of 5.0-6.6 days. Concentrations of unconjugated drug-related steroids circulating in plasma never exceeded about 0.1 microgram/ml. Mass spectroscopic analysis of isolated urinary and faecal metabolites indicated that the principal routes of biotransformation of oxendolone in man are similar to those of the endogenous androgens-namely, reduction of the 4,5-double bond, further reduction of the saturated 3-ketone to the 3 alpha-hydroxysteroid, and oxidation of the 17 beta-alcohol to the corresponding ketone, followed by conjugation, mainly with glucuronic acid, and excretion in the urine and bile.

Ro 15-1788 antagonizes the effects of diazepam in man without affecting its bioavailability

In a double-blind, placebo-controlled three-way cross over study, the efficacy of Ro 15-1788 200 mg, a new benzodiazepine antagonist, in blocking the amnesic, cognitive, psychomotor and subjective effects of diazepam 20 mg, was investigated in a group of six healthy male volunteers. The amnesic effects of diazepam were markedly attenuated by the combined administration of Ro 15-1788. The psychomotor and subjective effects of diazepam by mouth were most pronounced 2.5 h after administration. Concurrent oral administration of Ro 15-1788 completely prevented these effects at 2.5 h. Plasma diazepam concentrations observed after administration of the combination of diazepam and the antagonist did not differ from those observed following diazepam alone.

The percutaneous absorption and excretion of promestriene (3-propoxy-17 beta-methoxy-1,3,5(10)-estratriene) in rats and humans

The percutaneous absorption of 3H-promestriene (an antiseborrhoeic agent; 3-propoxy-17 beta-methoxy-1,3,5(10)-estratriene) was studied in rats and human subjects. Extensive and continual absorption of the tritium label (about 50% dose in 3 days) occurred in rats when the treated area of skin (ca. 30 micrograms/cm2) was occluded; when unabsorbed material was washed off after 6 h, a substantial proportion of the applied 3H (about 25% dose) had been absorbed to be excreted later. In contrast, less than 1% of the 3H applied to the skin of human volunteers (0.1-0.5 mg/cm2) was absorbed within 6 h and subsequently excreted. In rats, tissue concentrations of 3H were greatest in the liver, adrenals and ovaries.

The effect of PK5078, a new serotonin uptake inhibitor, on serotonin levels and uptake in human platelets, following administration to healthy volunteers

PK 5078 is a recently developed compound which inhibits specifically the neuronal reuptake of serotonin and enhance its release. PK 5078 was administered to healthy male volunteers in single and multiple oral doses and the effects on platelet serotonin uptake and content were examined. A significant dose-related inhibition of 3H-serotonin uptake by platelets was observed following single oral doses of PK 5078 (25-150 mg), with maximal inhibition at 75 mg. This was evident 2 h after dosing and was still marked after 10 h. Plasma collected from the subjects after dosing also had a considerable dose-related effect on the uptake of 3H-serotonin by untreated platelets. No significant alteration in platelet serotonin content was observed after single doses of PK 5078. When PK 5078 (50 mg) was administered twice daily for 9 days there was a rapid and sustained reduction in 3H-serotonin uptake by platelets, which returned to pretreatment levels 2 days after discontinuation of the drug. A similar response was observed when plasma from these subjects was incubated with untreated platelets. The rate of depletion of endogenous platelet serotonin was much slower with minimum levels being attained on the morning after the final dose. The recovery following withdrawal was also slow with serotonin levels approaching pre-dose values 14 days after the final dose of PK 5078.

Vasoactive intestinal polypeptide in obesity

Twenty-six patients who were more than 35 per cent above their ideal weight were examined before the introduction of a weight reduction programme. At the end of a three-month period, seven patients had lost more than 10 per cent of their body weight. These patients had significantly lower triglyceride levels, fasting gastric inhibitory polypeptide levels (GIP) and prolactin levels. Fasting vasoactive intestinal polypeptide levels (VIP) before commencing diet were raised in six of the 19 patients who subsequently did not lose weight whereas the seven patients who lost weight had normal VIP levels (X2 = 3.07, P less than 0.05). Patients with high VIP levels had higher triglyceride levels, higher mean C-terminal glucagon-like immunoreactivity (C-GLI) and higher post glucose infusion secretin levels. There was a significant correlation between triglycerides and VIP. The significance of abnormally high VIP levels in obesity and the inability of these patients to lose weight is discussed.

Absence of central effects in man of the benzodiazepine antagonist Ro 15-1788

The benzodiazepines are typified by a profile of side effects which includes drowsiness, ataxia and incoordination. Ro 15-1788, an imidazodiazepine derivative, exhibits marked antagonism of the behavioural and biochemical effects of the benzodiazepines in animals and man. It is devoid of any behavioural activity in animals, except at very high doses. In the present study the effects of single rising oral doses of Ro 15-1788 on cognitive, psychomotor and subjective function in man have been assessed using a battery of psychometric tests designed to identify the sedative action of the benzodiazepines. At all doses up to 600 mg, Ro 15-1788 demonstrated none of the classical behavioural effects of the benzodiazepines.

Effects of a single oral dose of 3-cyano-imipramine on serotonin uptake and content of platelets in healthy volunteers

Changes in platelet serotonin uptake and content were investigated following administration of a single oral dose of 3-cyano-imipramine to healthy volunteers. The uptake of 3H-serotonin by platelets harvested from these subjects was almost completely inhibited 4 h after dose administration. This inhibition continued for at least 24 h. Plasma taken from the subjects inhibited the uptake of 3H-serotonin by platelets isolated from non-treated subjects. A small but significant reduction in platelet serotonin content was observed 3.75 h after dosing and was still evident after 24 h.

Platelet uptake of serotonin following repeated administration of 3-cyano-imipramine to healthy volunteers

In a double blind, placebo-controlled study the effects of daily oral administration of 3-cyano-imipramine on the 3H-serotonin uptake capacity of platelets were investigated in healthy volunteers. The initial dose was 1 mg, rising to 3 mg daily for 7 days. A rapid and profound inhibition of 3H-serotonin uptake was observed in platelets isolated from the treated subjects. During repeated administration, uptake was reduced to less than 10% of pre-drug values. Five days after the final dose uptake had only partially recovered, to 53% of pre-drug values. A similar inhibition profile was observed when serum from the treated subjects was incubated with normal platelets and 3H-serotonin. The results establish 3-cyano-imipramine as a potent inhibitor of platelet serotonin uptake in humans.