Pharmacokinetics of temazepam after day-time and night-time oral administration

Timing of Novel Drug 1A-116 to Circadian Rhythms Improves Therapeutic Effects against Glioblastoma

The Ras homologous family of small guanosine triphosphate-binding enzymes (GTPases) is critical for cell migration and proliferation. The novel drug 1A-116 blocks the interaction site of the Ras-related C3 botulinum toxin substrate 1 (RAC1) GTPase with some of its guanine exchange factors (GEFs), such as T-cell lymphoma invasion and metastasis 1 (TIAM1), inhibiting cell motility and proliferation. Knowledge of circadian regulation of targets can improve chemotherapy in glioblastoma. Thus, circadian regulation in the efficacy of 1A-116 was studied in LN229 human glioblastoma cells and tumor-bearing nude mice.

METHODS

Wild-type LN229 and BMAL1-deficient (i.e., lacking a functional circadian clock) LN229E1 cells were assessed for rhythms in TIAM1, BMAL1, and period circadian protein homolog 1 (PER1), as well as Tiam1, Bmal1, and Rac1 mRNA levels. The effects of 1A-116 on proliferation, apoptosis, and migration were then assessed upon applying the drug at different circadian times. Finally, 1A-116 was administered to tumor-bearing mice at two different circadian times.

RESULTS

In LN229 cells, circadian oscillations were found for BMAL1, PER1, and TIAM1 (mRNA and protein), and for the effects of 1A-116 on proliferation, apoptosis, and migration, which were abolished in LN229E1 cells. Increased survival time was observed in tumor-bearing mice when treated with 1A-116 at the end of the light period (zeitgeber time 12, ZT12) compared either to animals treated at the beginning (ZT3) or with vehicle.

CONCLUSIONS

These results unveil the circadian modulation in the efficacy of 1A-116, likely through RAC1 pathway rhythmicity, suggesting that a chronopharmacological approach is a feasible strategy to improve glioblastoma treatment.

Creating and evaluating an opportunity for medication reconciliation in the adult population of South Africa to improve patient care

OBJECTIVE

Adverse drug events (ADEs) are a major cause of morbidity and mortality, with more than 50% of ADEs being preventable. Adverse Drug Reactions (ADRs) are typically the result of an incomplete medication history, prescribing or dispensing error, as well as over- or under-use of prescribed pharmacotherapy. Medication reconciliation is the process of creating the most accurate list of medications a patient is taking and subsequently comparing the list against the different transitions of care. It is used to reduce medication discrepancies, and thereby ultimately decreasing ADEs. However, little is known about medicine reconciliation activities among public hospitals in South Africa.

METHODS

Prospective quantitative, descriptive design among Internal and Surgical wards in a leading public hospital in South Africa.

RESULTS

145 study participants were enrolled. Over 1300 (1329) medicines were reviewed of which there was a significant difference (p = 0.006) when comparing the medications that the patient was taking before or during hospitalisation. A total of 552 (41.53%) interventions were undertaken and the majority of patients had at least 3.96 medication discrepancies. The most common intervention upon admission was transcribing the home medication onto the hospital prescription (65.2%) followed by medication duplication (13.44%). During patient's hospital stay, interventions included patient counselling (32.5%) and stopping the previous treatment (37.5%).

CONCLUSION

To ensure continuity of patient care, medication reconciliation should be implemented throughout patients' hospital stay. This involves all key professionals in hospitals.

Drug Use and Misuse in the Mountains: A UIAA MedCom Consensus Guide for Medical Professionals

Donegani, Enrico, Peter Paal, Thomas Küpper, Urs Hefti, Buddha Basnyat, Anna Carceller, Pierre Bouzat, Rianne van der Spek, and David Hillebrandt. Drug use and misuse in the mountains: a UIAA MedCom consensus guide for medical professionals. High Alt Med Biol. 17:157-184, 2016.-Aims: The aim of this review is to inform mountaineers about drugs commonly used in mountains. For many years, drugs have been used to enhance performance in mountaineering. It is the UIAA (International Climbing and Mountaineering Federation-Union International des Associations d'Alpinisme) Medcom's duty to protect mountaineers from possible harm caused by uninformed drug use. The UIAA Medcom assessed relevant articles in scientific literature and peer-reviewed studies, trials, observational studies, and case series to provide information for physicians on drugs commonly used in the mountain environment. Recommendations were graded according to criteria set by the American College of Chest Physicians.

RESULTS

Prophylactic, therapeutic, and recreational uses of drugs relevant to mountaineering are presented with an assessment of their risks and benefits.

CONCLUSIONS

If using drugs not regulated by the World Anti-Doping Agency (WADA), individuals have to determine their own personal standards for enjoyment, challenge, acceptable risk, and ethics. No system of drug testing could ever, or should ever, be policed for recreational climbers. Sponsored climbers or those who climb for status need to carefully consider both the medical and ethical implications if using drugs to aid performance. In some countries (e.g., Switzerland and Germany), administrative systems for mountaineering or medication control dictate a specific stance, but for most recreational mountaineers, any rules would be unenforceable and have to be a personal decision, but should take into account the current best evidence for risk, benefit, and sporting ethics.

Molecular clocks in pharmacology

Circadian rhythms regulate a vast array of biological processes and play a fundamental role in mammalian physiology. As a result, considerable diurnal variation in the pharmacokinetics, efficacy, and side effect profiles of many therapeutics has been described. This variation has subsequently been tied to diurnal rhythms in absorption, distribution, metabolism, and excretion, as well as in pharmacodynamic variables, such as target expression. More recently, the molecular basis of circadian rhythmicity has been elucidated with the identification of clock genes, which oscillate in a circadian manner in most cells and tissues and regulate transcription of large sets of genes. Ongoing research efforts are beginning to reveal the critical role of circadian clock genes in the regulation of pharmacologic parameters, as well as the reciprocal impact of drugs on circadian clock function. This chapter will review the role of circadian clocks in the pharmacokinetics and pharmacodynamics of drug response and provide several examples of the complex regulation of pharmacologic systems by components of the molecular circadian clock.

The role of clock genes in pharmacology

The physiology of a wide variety of organisms is organized according to periodic environmental changes imposed by the earth's rotation. This way, a large number of physiological processes present diurnal rhythms regulated by an internal timing system called the circadian clock. As part of the rhythmicity in physiology, drug efficacy and toxicity can vary with time. Studies over the past four decades present diurnal oscillations in drug absorption, distribution, metabolism, and excretion. On the other hand, diurnal variations in the availability and sensitivity of drug targets have been correlated with time-dependent changes in drug effectiveness. In this review, we provide evidence supporting the regulation of drug kinetics and dynamics by the circadian clock. We also use the examples of hypertension and cancer to show current achievements and challenges in chronopharmacology.

The influence of circadian rhythms on the kinetics of drugs in humans

In clinical practice, it is important to consider circadian rhythms in pharmacokinetics and cell responses to therapy in order to design proper protocols for drug administration. Scientists have arrived at this conclusion after several experiments in animals and in humans have clearly demonstrated that all organisms are highly organised according to circadian rhythms. These temporal cycles influence different physiological functions and, consequently, can influence the pharmacokinetic phases of drugs. A drug's pharmacokinetics can be modified according to the time of drug administration. In fact, the circadian changes of > 100 different compounds have been documented. The results obtained have led several scientific societies to provide guidelines concerning the timing of drug dosing for anticancer, cardiovascular, respiratory, anti-ulcer, anti-inflammatory, immunosuppressive and antiepileptic drugs. Absorption may be influenced by circadian rhythms and most lipophilic drugs seem to be absorbed faster when the drug is taken in the morning compared with the evening; for water-soluble compounds, no circadian variation in the absorption of drugs has been found. Concerning drug distribution, the higher the blood flow fraction an organ receives, the higher the rate constant for transferring drugs out of the capillaries. This drug pharmacokinetic phase may be influenced by circadian variations in the protein binding of acidic and basic drugs. Drug metabolism may be influenced by daily modifications of blood flow. For drugs with a high extraction ratio, metabolism depends on hepatic blood flow, while that of drugs with a low extraction ratio depends on liver enzyme activity. Hepatic blood flow has been shown to be greatest at 8 am and metabolism seems to be reduced during the night. Finally, concerning drug elimination, the clearance of 'flow-limited' drugs that present a high extraction rate is affected by the blood flow delivered to the organ, independent of the cardiac output fraction supplied. Chronopharmacokinetics can explain individual differences in drug levels revealed by therapeutic drug monitoring and can be used to optimise the management of patients receiving drug therapy.

Determination of temazepam and temazepam glucuronide by reversed-phase high-performance liquid chromatography

A rapid and sensitive method for extracting temazepam from human serum and urine is presented. Free temazepam is extracted from plasma and urine samples using n-butyl chloride with nitrazepam as the internal standard. Temazepam glucuronide is analyzed as free temazepam after incubating extracts with beta-glucuronidase. Separation is achieved using a C8 reversed-phase column with a methanol-water-phosphate buffer mobile phase. An ultraviolet detector operated at 230 nm is used and a linear response is observed from 20 ng/ml to 10 micrograms/ml. The limit of detection is 15.5 ng/ml and the limit of quantitation is 46.5 ng/ml. Coefficients of variation are less than 10% for concentrations greater than 50 ng/ml. Application of the methodology is demonstrated in a pharmacokinetic study using eight healthy male subjects.

Chronopharmacology of oral nitrates in healthy subjects

The pharmacokinetics and the hemodynamic effects (blood pressure, heart rate) of oral organic nitrates have been investigated in healthy subjects after oral single-dose application either in the morning or in the evening. Isosorbide-5-monitrate (IS-5-MN, 60 mg) was administered as an immediate-release tablet or as a slow-release formulation. Isosorbide dinitrate (ISDN, 20 mg) was ingested as an immediate-release tablet. After administration of IS-5-MN as an immediate-release tablet, the drug was more rapidly absorbed in the morning (tmax of 0.9 h) than in the evening (tmax of 2.1 h). The rapid absorption led to more pronounced effects in the morning, at which time maximum drug concentrations occurred at the same time as peak effects were observed. After evening administration, however, peak effects were in advance of the maximum drug concentrations. No chronokinetics were observed after application of the slow-release formulation of IS-5-MN. In accordance with the results of the immediate-release formulation, peak effects of the slow-release preparation occurred significantly earlier than peak drug concentrations after evening than after morning dosing. ISDN bioavailability was higher after morning than after evening administration and hemodynamic effects were more pronounced in the evening than in the morning. These results show that daily variations in pharmacokinetics and/or hemodynamic effects can be observed with oral nitrates. In addition, galenic formulation can influence the time-specified pharmacokinetics of IS-5-MN.

Oxidative versus conjugative biotransformation of temazepam

Twenty-four healthy volunteers, aged 21-59 years, received single 30 mg oral doses of the benzodiazepine hypnotic temazepam. Levels of intact temazepam were determined in multiple plasma samples drawn during 48 h after dosage. Intact temazepam, its direct glucuronide conjugate, and the conjugate of its demethylated (oxidized) metabolite oxazepam were measured in two consecutive 24-h urine collections. Mean kinetic variables for temazepam in plasma were: peak plasma level (Cmax), 873 ng ml-1; time of peak, 1.36 h after dosage; volume of distribution, 0.961 kg-1; elimination half-life 9.9 h; clearance, 1.16 ml min-1 kg-1. Volume of distribution increased significantly with body weight (r = 0.67, p less than 0.001), and Cmax decreased with weight (r = -0.58, p less than 0.01). Only 0.2 per cent of the dose was excreted as intact temazepam, and negligible amounts as intact oxazepam. However, 39 per cent of the dose was recovered as temazepam glucuronide, and oxazepam glucuronide accounted for another 4.7 per cent of the dose. The remainder was not accounted for. Thus, a significant fraction of temazepam clearance occurs by direct glucuronide conjugation, with the conjugate temazepam glucuronide excreted in urine. A much smaller fraction undergoes parallel oxidation to form oxazepam, which is subsequently conjugated to oxazepam glucuronide and excreted in urine.

Pharmacokinetics of 4' epi-adriamycin after morning and afternoon intravenous administration

The chronopharmacokinetics of 4' epi-adriamycin (Epi) have been studied in ten patients with gynecological malignancies. The drug (45 mg m-2) was administered as a short time (5.0 min) intravenous infusion at 7 a.m. and 7 p.m., in a randomized cross-over design. The pharmacokinetics of Epi were evaluated according to the statistical moment theory. Morning and afternoon dosing of Epi was not bioequivalent. The area under the plasma concentration-time curve (AUC), the maximum plasma concentration (Cmax), mean residence time (MRT) and the terminal half-life time (t1/2) could differ by more than 35% after morning and afternoon dosing. The inter-individual variation of AUC and Cp,max were larger after morning dosing than after afternoon dosing (P less than 0.04). The morning dose of Epi resulted in higher values of AUC in seven of the ten treated patients as compared to the afternoon dose. The terminal half-life times were shorter in eight of the patients after the morning dose.

Effects of flunitrazepam and triazolam in man: are they influenced by the time of ingestion?

Five healthy young volunteers were given flunitrazepam 1 mg, triazolam 0.25 mg or placebo at 2 a.m. or 9 a.m. in a double blind, cross-over study. The aim was to investigate the cyclic variations mainly in residual effects of the drugs, but also in sleep onset latency and pharmacokinetics. The study suggested cyclic variations in mood, psychometric tests and in sleep onset latency.