Interaction between different extracts of Hypericum perforatum L. from Serbia and pentobarbital, diazepam and paracetamol.

Herb-drug interactions are an important safety concern and this study was conducted regarding the interaction between the natural top-selling antidepressant remedy Hypericum perforatum (Hypericaceae) and conventional drugs. This study examined the influence of acute pretreatment with different extracts of Hypericum perforatum from Serbia on pentobarbital-induced sleeping time, impairment of motor coordination caused by diazepam and paracetamol pharmacokinetics in mice. Ethanolic extract, aqueous extract, infusion, tablet and capsule of Hypericum perforatum were used in this experiment. The profile of Hypericum perforatum extracts as well as paracetamol plasma concentration was determined using RP-HPLC analysis. By quantitative HPLC analysis of active principles, it has been proven that Hypericum perforatum ethanolic extract has the largest content of naphtodianthrones: hypericin (57.77 µg/mL) and pseudohypericin (155.38 µg/mL). Pretreatment with ethanolic extract of Hypericum perforatum potentiated the hypnotic effect of pentobarbital and impairment of motor coordination caused by diazepam to the greatest extent and also increased paracetamol plasma concentration in comparison to the control group. These results were in correlation with naphtodianthrone concentrations. The obtained results have shown a considerable influence of Hypericum perforatum on pentobarbital and diazepam pharmacodynamics and paracetamol pharmacokinetics.

Effect of a high-fat meal on absorption and disposition of lipophilic compounds: the importance of degree of association with triglyceride-rich lipoproteins.

Following a high-fat meal, triglyceride-rich lipoproteins (TRL) are assembled in the gut and absorbed via the lymph into the blood circulation, producing a temporal hyperlipidemia. The purpose of this study is to verify the hypothesis that this transient acute postprandial hyperlipidemia affects the pharmacokinetics of lipophilic drugs on both absorption and disposition levels by the same underlying mechanism, namely the association of active lipophilic compounds with TRL in the plasma (disposition) or within the enterocyte (lymphatic transport). This concept was assessed in rats using two model compounds, DDT with high affinity to chylomicrons and diazepam which does not bind to chylomicrons. Oral administration of peanut oil significantly increased the AUC of plasma DDT concentrations following its IV bolus administration in comparison to a water treated group. On the other hand, the AUC of diazepam following IV bolus administration was the same in oil and water treated rats. While DDT is known to have significant lymphatic bioavailability, diazepam has negligible intestinal lymphatic transport (0.014+/-0.004% of a given dose). In conclusion, lipophilic molecules that bind extensively to TRL will be prone to both intestinal lymphatic transport and to post-absorptive changes in disposition (decrease in clearance and volume of distribution) following a high-fat meal.

Combined approach for high-throughput preparation and analysis of plasma samples from exposure studies.

In drug discovery today, drug exposure is determined in preclinical efficacy and safety studies and drug effects are related to measured concentrations rather than to the administered dose. This leads to a strong increase in the number of bioanalytical samples, demanding the development of higher throughput methods to cope with the increased workload. Here, a combined approach is described for the high-throughput preparation and liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis of drug levels in plasma samples from the preclinical efficacy and safety studies, i.e. exposure studies. Appropriate pharmacokinetic (PK) compartmental models were fitted to data from PK screening studies in the rat, which were subsequently used to simulate the expected plasma concentrations of the respective exposure studies. Information on the estimated drug concentrations was used to dilute the samples to appropriate concentration levels. A Tecan Genesis RSP liquid handling system was utilized to perform automated plasma sample preparation including serial dilution of standard solutions, dilution of plasma samples, addition of internal standard solution and precipitation with acetonitrile. This robotic sample preparation process permitted two studies of 1-96 samples each to be run simultaneously. To ensure the performance of this method the accuracy and precision for diazepam were examined. Two novel drugs were used to illustrate the suggested approach. In conclusion, our method for sample preparation of exposure samples, based on the combined use of PK simulations, a liquid handling system and a fast LC/MS/MS method, increased the throughput more than three times and minimized the errors, while maintaining the required accuracy and precision.

[Dietary supplements--surprise pills?]. / Kosttilskudd--forundringspakke i pilleform?

BACKGROUND: Sales of herbal dietary supplements have increased dramatically. A patient case drew our attention to the problem of incomplete declaration of content. METHODS: Two dietary supplements which the manufacturers claim to be natural, extremely fat-burning and energizing were analysed, as were urine and serum samples from persons taking these supplements. RESULTS: Surprisingly, the herbal dietary supplements contained drugs. Diazepam, clonazepam, ephedrine and metabolites were found when analyzing serum samples after intake of the dietary supplement Thermo-X 650, ephedrine and phenylpropanolamine after intake of the Purple Burn supplement. INTERPRETATION: Use of herbal dietary supplement can have serious consequences, for instance through interactions with drug therapy. Consumers must be given sufficient product information for safe use.

Interaction of drugs and Chinese herbs: pharmacokinetic changes of tolbutamide and diazepam caused by extract of Angelica dahurica.

The inhibitory effects of Angelica dahurica root extract on rat liver microsomal cytochrome P450 and drug-drug interactions were studied. The 2alpha- and 16alpha-hydroxylase activity of testosterone were most strongly inhibited, with 17.2% and 28-5% of their activity remaining, respectively, after oral administration of A. dahurica extract at a 1 g kg(-1) dose. 6beta-Hydroxylase activity was also inhibited, with 70% of its activity remaining, under the same conditions. In addition, treatment with the extract inhibited the metabolism of tolbutamide, nifedipine and bufuralol. These results showed that the extract inhibited the various isoforms of cytochrome P450 such as CYP2C, CYP3A and CYP2D1. The A. dahurica extract delayed elimination of tolbutamide after intravenous administration at a 10 mg kg(-1) dose to rats. Thus, the extract altered the liver intrinsic clearance. It had little effect, however, on the pharmacokinetic parameters of diazepam after intravenous administration at 10 mg kg(-1). Since diazepam showed high clearance, it underwent hepatic blood flow rate-limited metabolism. Therefore, the change of intrinsic clearance had little effect on hepatic clearance. However, the Cmax value after oral administration of diazepam with extract treatment was four times that with non-treatment. It was suggested that the first-pass effect was changed markedly by the extract. High-dose (1 g kg(-1)), but not low dose (0.3 g kg(-1)), administration of A. dahurica extract increased significantly the duration of rotarod disruption following intravenous administration of diazepam at 5 mg kg(-1). It was concluded that administration of A. dahurica extract has the potential to interfere with the metabolism, by liver cytochrome P450, of other drugs.

Low level hyperbaric antagonism of diazepam's locomotor depressant and anticonvulsant properties in mice.

Exposure to 12 atmospheres absolute (12 ATA) helium oxygen gas (heliox) (low level hyperbaric exposure) antagonizes the behavioral effects of ethanol and n-propanol, but not morphine. These and other results indicate that the mechanism of the antagonism is direct (pharmacodynamic) and selective. Our study further investigates the selectivity of low level hyperbaric antagonism by testing its effectiveness against diazepam, a high affinity binding drug that acts via allosteric modulation of GABAA receptors. C57BL/6J mice received injections i.p. of vehicle or diazepam, and were then exposed to 1 ATA air, 1 ATA heliox or 12 ATA heliox. Exposure to 12 ATA heliox antagonized the locomotor depressant effect of 4 and 6 mg/kg, but not 8 mg/kg diazepam. Hyperbaric exposure also antagonized the anticonvulsant effect of 8 and 24 mg/kg, but not 4 mg/kg, diazepam vs. 300 mg/kg isoniazid. Exposure to 12 ATA heliox did not significantly affect blood concentrations of diazepam or its metabolite n-desmethyl diazepam. The pharmacological characteristics of the antagonism (direct, surmountable, rightward shift in diazepam's dose-response curve) closely matched those seen in previous studies for hyperbaric antagonism of ethanol. The results add to the evidence that low level hyperbaric exposure is a direct, mechanistic antagonist that selectively antagonizes drugs that act via perturbation or allosteric modulation of receptor function. Moreover, the results suggest that allosteric coupling pathways, which transduce binding events on ligand-gated ion channels, may represent initial sites of action for ethanol.

Different sensitivity of pain-related chemosensory potentials evoked by stimulation with CO2, tooth pulp event-related potentials, and acoustic event-related potentials to the tranquilizer diazepam.

1. The aim of this study was to investigate the sensitivity of pain-related potentials used in experimental pain models to the non-specific effects of the tranquilizer diazepam. Pain-related potentials were recorded after painful stimulation of the nasal mucosa with CO2 and after painful stimulation of the tooth pulp. Acoustically evoked potentials were measured in order to compare their sensitivity to the tranquilizer diazepam with the sensitivity of the pain-related potentials. 2. Twenty volunteers participated in this randomised, double-blind, three-fold crossover study. Measurements were obtained before and 20 min after the administration of the drug. Event-related potentials were recorded after painful stimulation of the nasal mucosa with CO2 (two stimulus intensities: 60% v/v and 70% v/v CO2), after painful stimulation of the tooth pulp (two stimulus intensities: 2.2 x and 3.3 x detection threshold), and after non-painful acoustical stimulation of the right ear. The subjects rated the perceived intensity of the painful stimuli by means of a visual analogue scale. In addition the spontaneous EEG was analysed in the frequency domain and the vigilance of the subjects was assessed in a tracking task. 3. Diazepam reduced significantly the amplitudes of the event-related potentials after painful stimulation of the tooth pulp and after acoustical stimulation. In contrast only a small, statistically non-significant reduction could be found after painful stimulation with CO2. The pain ratings of the painful stimuli were not affected by diazepam. Diazepam reduced the performance of the tracking task. A decrease of arousal could be found in the alpha 2-range, whereas in the beta 2 and the theta-range the power density increased under diazepam. 4. We demonstrated that event-related potentials after painful stimulation of the nasal mucosa with CO2 are less affected by the nonspecific effects of the tranquilizer diazepam than event-related potentials after painful stimulation of the tooth pulp. The effects of diazepam on the tracking task, the spontaneous EEG and the event-related potentials clearly confirm its sedative properties. Diazepam had no analgesic effect measurable by pain intensity estimates.

The actual dose delivery from a diazepam enema differs depending on the patients position during administration.

In a randomized single-blind cross-over study on 14 volunteers the relation between dose, effect and serum concentration was studied when diazepam in solution was administered in a dose of 0.5 mg/kg bodyweight rectally with the volunteer placed either laterally or prone. When lying prone the delivered diazepam dose was on average 24% higher compared to in the lateral position. The difference in delivered dose affected sedation as well as serum concentration but did not prolong recovery time. At the time of clinical recovery, the serum concentration was still at a very high level. Oxygen (p02) and carbon dioxide (pCO2) tensions were monitored transcutaneously in 9 subjects and were unaffected by the sedative level. The study suggests that when diazepam enemas similar to the ones used here, they should be administered with the patient in a prone position.

A comparison of two sedative premedications for minor oral surgery under local anaesthesia.

Two commonly used drug combinations were studied as premedications before surgical 3rd molar removal under local anaesthesia. The study was randomized, crossover and double-blind in 12 patients. Our routine premedication for lengthy operations, consisting of diazepam 10 mg p.o. plus i.m. scopolamine 0.006 mg/kg and morphine 0.2 mg/kg, was compared with a combination of diazepam 10 mg p.o. plus metoprolol 50 mg p.o. The latter combination was expected to cause fewer central nervous system side effects and be more suitable for out-patient surgery. Drug levels in blood, physiological and biochemical indicators of operation-related stress, CNS side effects, and the patients' subjective preferences were monitored. Both combinations were equally accepted by the patients, but the diazepam/scopolamine/morphine combination caused clearly more side effects after discharge than diazepam/metoprolol. The operation-related haemodynamic changes and plasma catecholamine responses were similar after both premedications.

Variability in heparin effect on serum drug binding.

Heparinized saline was given to seven men and one woman, aged 21 to 42 yr, after a 14-hr fasting period and 2 hr after breakfast; blood was collected in nonoheparinized tubes. Diazepam (D alpha) and warfarin (W alpha) free fractions were determined in serum by equilibrium dialysis to which radiolabeled drug was added. After 50 U heparin (Harris LO14) intravenously, the maximum effect on D alpha, W alpha, and free fatty acids (FFA) developed in 5 min and lasted 20 to 30 min. D alpha rose and W alpha fell (p < 0.01) at 5 min. Cumulative doses of heparin increased FFAs (F4,16 = 18.29, p < 0.0005). D alpha rises (r = 0.73, p < 0.001) and W alpha falls (r = -0.74, p < 0.001) correlated with changes in FFAs. D alpha rises and W alpha falls were greater postprandially than in the fasted state (p < 0.01). Five subjects were randomly assigned up to 400 U intravenously of each of two different heparin lots (Harris LO14, and Organon LA39.) The FFA rises (reflecting heparin lipolytic activity, F1,32 = 179.62, p < 0.0005), D alpha rises (F1,32 = 34.22, p < 0.0005), and the W alpha falls (F1,32 = 33.20, p < 0.0005) by heparin Harris LO14 were greater than those by heparin Organon LA39. Although small doses of heparin, such as those in heparin locks, can affect drug binding, the extent and variability of the effect depends on the biologic activity of the heparin, and varies with manufacturer and lot, exact time of sampling, and eating.

Comparison of diazepam and flunitrazepam for sedation during local anaesthesia for bronchoscopy.

Diazepam and flunitrazepam were compared as amnesic and sedative adjuncts to local anaesthesia for diagnostic bronchoscopy in 92 patients. After local anaesthesia of the pharynx, larynx and trachea with lignocaine, atropine plus diazepam of flunitrazepam was injected i.v. The co-operation of the patients and the technical circumstances under which the bronchoscopy was performed were good in each group. None of the treatments significantly modified arterial pressure or heart rate. Two hours after the injection, flunitrazepam 0.01 mg kg-1 more frequently caused amnesia for pictures shown to the patients during the first 15 min after injection (failure to recall 42--75%, and for bronchoscopy 67%), than did diazepam 0.125 mg kg-1 (failure to recall 21--67%; bronchoscopy 38%). Double doses of the drugs caused amnesic actions similar to those of flunitrazepam 0.01 mg kg-1. When failure to recall was assessed on the following day, 29% and 5% of the patients remembered bronchoscopy after flunitrazepam 0.01 and 0.02 mg kg-1 respectively; after diazepam 0.125 and 0.25 mg kg-1 the corresponding percentages was 59% and 30% (P less than 0.05% v. fluintrazepam). The ability to stand and walk on a stright line was similar after the smaller doses of both drugs, but after the larger doses recovery was slower after flunitrazepam. Psychomotor performance was still distinctly impaired 2 h after the injection of the larger doses.

The effects of chlordesmethyldiazepam on behavioral performance and subjective judgment in normal subjects.

Eight normal subjects were tested on a battery of subjective and psychological tests 12 hours after a hypnotic dose of chlordesmethyldiazepam (1 or 2 mg), amylobarbitone sodium (100 mg), and a placebo. The tests included self-ratings of hypnotic effects and alertness; reactiontime, card-sorting, coding and cancellation tasks; arithmetic; and tapping. Before each task, test anxiety and performance expectation was self-rated; and after the task, judgment of performance was self-rated. Residual effects were definitely detectable after the 2-mg dose of benzodiazepine with both behavioral impairment and subjective hangover. Both the 1-mg dose and the barbiturate were almost devoid of such effects. Very few drug effects on test anxiety and performance judgment were discerned. Plasma concentrations of amylobarbitone were related to decreases in test anxiety and of chlordesmethyldiazepam with ratings of sleepiness.

Clinical and psychological effects of intravenous diazepam related to plasma levels. A controlled, double-blind, cross-over study in oral surgery involving local analgesia.

In a controlled, double-blind, cross-over study with diazepam (DZ) and placebo (PL) various clinical, psychological, and pharmacological parameters were studied in 33 patients having identical impacted third molars removed. The patients were admitted to the study consecutively and nonparametric statistics were used throughout the study for the evaluation (Wilcoxon's matched-pairs signed test). The following aspects were examined: Continous reaction times (CRT), rating scales (a.m. Beecher), blood pressure, pulse, plasma concentration of DZ and of N-desmethyldiazepam, visual changes, amnesia, adverse reactions, recalling of duration of surgery, orientation in time, phlebitis, and final evaluation performed by the patient. The operative conditions were found to be excellent, and only a few adverse effects were noticed. The patients expressed an overall enthusiasm about the sedation. In the rating scales only the predominantly sedative items were affected and not the anxiolytic ones. Neither the heart rate nor the systolic blood pressure were significantly changed; on the contrary, the DZ-group was less affected than the PL-group when maximum increases in the systolic blood pressure were compared in the two groups. The continuous reaction times were significantly correlated to the plasma concentrations of diazepam, especially 1 hour after sedation. The reported recurrence of initial clinical symptoms 6 hours after sedation due to the N-desmethyldiazepam could not be demonstrated in this study. The CRT has proved itself to be of great value in discriminating between different kinds of cerebral affections; the patients with DZ-intoxication showed significantly faster CRT 1 hour after injection than did patients suffering from well-documented cerebral disorders such as organic brain damage or hepatic encephalopathia.

Plasma levels of diazepam after parenteral and rectal administration in children.

Plasma levels of diazepam and N-desmethyldiazepam were investigated in 19 children by a gas chromatographic method permitting the use of capillary sample. Intravenous administration was studied in 3 children and the plasma level curves showed a rapid decline during the first hour. Absorption and elimination after rectal administration of a solution in 16 children were similar to those after intramuscular administration. Diazepam given by suppository to 5 children gave much lower plasma levels and delayed time to peak levels. Recurrence of seizures in 2 children indicated that the anticonvulsants plasma level was of the order of 150 to 200 mug/liter. No significant side effects were observed. Thus rectal administration of a solution of diazepam is a practical method to arrest convulsions in children.