Pharmacodynamics and pharmacokinetics of insulin detemir and insulin glargine 300 U/mL in healthy dogs

Insulin glargine 300 U/mL and insulin detemir are synthetic long-acting insulin analogs associated with minimal day-to-day variability or episodes of hypoglycemia in people. Here, 8 healthy purpose-bred dogs each received 2.4 nmol/kg subcutaneous injections of insulin detemir (0.1 U/kg) and insulin glargine 300 U/mL (0.4 U/kg) on 2 different days, >1 wk apart, in random order. Blood glucose (BG) was measured every 5 min, and glucose was administered intravenously at a variable rate with the goal of maintaining BG within 10% of baseline BG ("isoglycemic clamp"). Endogenous and exogenous insulin were measured for up to 24 h after insulin injection. The effect of exogenous insulin was defined by glucose infusion rate or a decline in endogenous insulin. Isoglycemic clamps were generated in all 8 dogs after detemir but only in 4 dogs after glargine. Median time to onset of action was delayed with glargine compared to detemir (4.0 h [3.3-5.8 h] vs 0.6 h [0.6-1.2 h], P = 0.002). There was no difference in time to peak (median [range] = 6.3 h [5.0-21.3 h] vs 4.3 h [2.9-7.4 h], P = 0.15) or duration of action (16.3 h [6.1-20.1 h] vs 10.8 h [8.8-14.8 h], P = 0.21) between glargine and detemir, respectively. Glargine demonstrated a peakless time-action profile in 4/8 dogs. The total metabolic effect and peak action of detemir was significantly greater than glargine. Significant concentrations of glargine were detected in all but 1 dog following administration. Glargine might be better suited than detemir as a once-daily insulin formulation in some dogs based on its long duration of action and peakless time-action profile. Day-to-day variability in insulin action should be further assessed for both formulations.

Die rationalisierte Literaturrecherche

Versteht man die Literaturrecherche als eine gehobene Dienstleistung, für die ein echtes Bedürfnis vorliegt und der Bedarf sich ständig ausweitet, so kann letzterer von einer Organisation rational und rationell nur befriedigt werden durch teilweise Dezentralisation der Sucharbeit, durch einen hohen Grad an Arbeitsteiligkeit im eigenen Organisationsbereich, durch klare, den Arbeitsablauf regelnde Anweisungen sowie durch Anwendung technisch hochentwickelter Dokumentationsverfahren. Neben die Inhaltsanalyse des Suchauftrags, wodurch die Suchstrategie festgelegt wird, tritt die Bedarfsanalyse, wodurch Art und Umfang der nachzuweisenden Dokumente sowie die Methode des Suchverfahrens bestimmt werden. Klassische, mechanische und elektronische Recherchen bestehen gleichberechtigt nebeneinander und ergänzen sich im Einzelfalle in geeigneter Kombination. Literaturnachweis und Literaturbeschaffung können für eine rationelle Erledigung weder örtlich noch organisatorisch getrennt werden. Apparative und bibliothekarische Ausstattung der Dokumentationsstelle ist ausschließlich am Bedarf zu orientieren und diesem ständig anzupassen.

Rationalisierung der Literaturerfassung in Spezialdokumentationen

Die Erfassungsstrategie für Aufbau und aktuelle Vervollständigung einer Literaturspezialdokumentation wird am Beispiel der Spezialdokumentation der Literatur über die Wirkstoffe des pharmazeutischen „Bayer”-Sortiments entwickelt. Das sehr aufwendige Erfassungssystem von Primärliteratur kann nur durch ständige statistische Analysen der Zeitschriftenverteilung an die Wirklichkeit adaptiert und rationell gestaltet werden. Die Ergebnisse einer solchen Analyse werden mitgeteilt. Sie sind gut mit der Hypothese vereinbar, daß es für das Erscheinen von Spezialliteratur zeitschriftenspezifische Schwellen gibt, deren Logarithmen annähernd normalverteilt sind. Hierauf kann man Schätzungen über den tatsächlichen Umfang der erfaßbaren Spezialliteratur sowie über den erforderlichen Mehraufwand an Durchsicht von Primärliteratur für den Fall, daß höhere Erfassungsquoten angestrebt werden, aufbauen.

Kontingenztafelanalyse unabhängiger Daten in der Arzneimittelprüfung

Zur statistischen Analyse vierclimensionaler kategorialer Daten aus kontrollierten Arzneimittelprüfungen wird eine problemadäquate additive Zerlegung der Unabhängigkeitshypothese vorgeschlagen. Mehrfachassoziationen werden mittels der Hypothesen von Babtlett und Roy-Kastenbaum geprüft. Das Problem ihrer Übertragbarkeit auf entsprechende Randtafeln wird durch Prüfung ausschließender Hypothesen nach Ku und Kullback umgangen. Ein Anwendungsbeispiel wird gegeben.

Vergleich biologischer Wirkungen mittels programmierter Probitanalyse

Es wird ein für die IBM 7074 erstelltes, der Wertbemessung biologisch aktiver Wirkstoffe bei alternativem Effekt dienendes Programm beschrieben. Typische Anwendungsbeispiele werden geschildert. Das Modell, der Vergleich mehrerer Logdosis-Probit-Regressionsgeraden, wird in mathematisch anspruchsloser Weise besprochen, seine Annahmen werden diskutiert, seine iterativen Schätzverfahren begründet. Hinweise zur Interpretation seiner Prüfverfahren werden gegeben.

Das Programm enthält eine Reihe von Fehlerprüfungen, da es als Routineverfahren störungsfrei laufen muß. Das dokumentationsgerecht gestaltete Befundformular und die Ausgabelisten werden demonstriert.

Versuchspläne zur Testung auf Arzneimittelsicherheit vor Beginn der klinischen Prüfung

Bevor eine neu synthetisierte oder isolierte und biologisch aktive Forschungssubstanz in die klinische Prüfung gegeben wird, muß sie nach dem derzeitigen Stand der Wissenschaft auf Sicherheit getestet werden. Dies erfolgt im Probandenversuch, wobei das Prinzip der Freiwilligkeit bei voller Aufklärung gewährleistet sein muß. Die Zahl der Probanden soll möglichst klein, aber groß genug für eine verläßliche Urteilsfindung gewählt werden.

Zielvariable sind Laborgrößen und Größen der Vitalfunktionen. Da die Zahl der Zielvariablen zu der Zahl der Probanden in ein vertretbares Verhältnis gebracht werden muß, muß eine Variablenvorauswahl an Hand der Vorinformation aus pharmakologischen und toxikologischen Tierversuchen erfolgen. Eine zusätzliche Variablenreduktion wird durch Selbstversuche oder Probandenstichversuche erreicht. Hierzu müssen zusätzlich Meßwerte vor Applikation der Substanz erhoben werden, damit diese Entscheidung nicht nur auf die wenig allgemeinverbindlichen klinischen Normbereiche, sondern auch auf die individuelle Ausgangslage gegründet werden kann.

Das endgültige Urteil wird aus einem im biometrischen Sprachgebrauch »kontrollierten« Versuch gewonnen. Kontrolliert werden müssen Zeittrends, die sich aus vielerlei Gründen bei den Probanden, bei den Untersuchern und in den Labors einschleichen und die biologische Aktivität der Forschungssubstanz nach beiden Richtungen verfälschen können. Zur Gewinnung einer verläßlichen Nullinie der Wirkung ist die Einbeziehung von Placebo-Applikationen unerläßlich. Damit die Probandenzahl nied. rig gehalten werden kann, sollte der Individualvergleich dem Gruppenvergleich vorgezogen werden. Für untersucheroder laborabhängige Zielvariable müssen mehr als ein Untersucher oder ein Labor einbezogen werden.

Entsprechende Versuchspläne, die sich in der Praxis als durchführbar erwiesen und bewährt haben, werden vorgeschlagen und Hinweise zu ihrer Auswertung gegeben. Nimmt man hierbei einen möglichen Autokorrelationsfehler in Kauf, liegt man in der Deutung der Versuchsergebnisse auf der Seite der Arzneimittelsicherheit.

Detection of Strongylus vulgaris in equine faecal samples by real-time PCR and larval culture - method comparison and occurrence assessment

Background

Strongylus vulgaris has become a rare parasite in Germany during the past 50 years due to the practice of frequent prophylactic anthelmintic therapy. To date, the emerging development of resistance in Cyathostominae and Parascaris spp. to numerous equine anthelmintics has changed deworming management and the frequency of anthelmintic usage. In this regard, reliable detection of parasitic infections, especially of the highly pathogenic S. vulgaris is essential. In the current study, two diagnostic methods for the detection of infections with S. vulgaris were compared and information on the occurrence of this parasite in German horses was gained. For this purpose, faecal samples of 501 horses were screened for S. vulgaris with real-time PCR and an additional larval culture was performed in samples of 278 horses. A subset of 26 horses underwent multiple follow-up examinations with both methods in order to evaluate both the persistence of S. vulgaris infections and the reproducibility of each diagnostic method.

Results

The real-time PCR revealed S. vulgaris-DNA in ten of 501 investigated equine samples (1.9%). The larval culture demonstrated larvae of S. vulgaris in three of the 278 samples (1.1%). A direct comparison of the two methods was possible in 321 samples including 43 follow-up examinations with the result of 11 S. vulgaris-positive samples by real-time PCR and 4 S. vulgaris-positive samples by larval culture. The McNemar’s test (p-value = 0.016) revealed a significant difference and the kappa values (0.525) showed a moderate agreement between real-time PCR and larval culture.

Conclusions

The real-time PCR detected a significantly higher proportion of positives of S. vulgaris compared to larval culture and should thus be considered as a routine diagnostic method for the detection of S. vulgaris in equine samples.

Effects of single-shot and steady-state propofol anaesthesia on rocuronium dose-response relationship: a randomised trial

BACKGROUND

Similar to volatile anaesthetics, propofol may influence neuromuscular transmission. We hypothesised that the administration of propofol influenced the potency of rocuronium depending on the duration of the administration.

METHODS

After consent, patients scheduled for elective surgery randomly received rocuronium either after induction of anaesthesia with propofol (2 min of propofol, n = 36) or after 30 min of propofol infusion (30 min of propofol, n = 36). Remifentanil was given in both groups. Neuromuscular monitoring was performed by calibrated electromyography. The dose-response relationship of rocuronium was determined with a single-bolus technique (0.07, 0.1, 0.15, 0.2, 0.3 and 0.45 mg/kg rocuronium). The primary endpoints were the ED50 and ED95 of rocuronium after 2 and 30 min propofol. Data are presented as means with (95% confidence interval). The trial is registered with the Eudra-CT: 2009-012815-16.

RESULTS

A total of 72 patients were included. Time to maximal neuromuscular blockade was significantly shorter in patients after 30 min of propofol [3.3 min (2.9-3.7)] compared with patients anaesthetised with 2 min of propofol [4.6 min (4.0-5.2)]. After 30 min of propofol, the slope of the dose-response curve was significantly steeper (30 min of propofol: 4.34 [3.62-5.05]; 2 min of propofol: [3.34 (2.72-3.96)], resulting in lower ED95 values of rocuronium (30 min of propofol: 0.287 mg/kg [0.221-0.368]; 2 min of propofol [0.391 mg/kg (0.296-0.520)]. The ED50 were not different between groups.

CONCLUSION

The potency of rocuronium was significantly enhanced after propofol infusion for 30 min. Estimates of potency those are usually determined during steady-state anaesthesia might underestimate rocuronium requirements for endotracheal intubation at the time of induction.

Pharmacological profile of 2-bromoterguride at human dopamine D2, porcine serotonin 5-hydroxytryptamine 2A, and α2C-adrenergic receptors, and its antipsychotic-like effects in rats

Dopaminergic, serotonergic, and adrenergic receptors are targets for therapeutic actions in schizophrenia. Dopamine D2 receptor partial agonists such as aripiprazole represent a treatment option for patients with this severe disorder. The ineffectiveness of terguride, another D2 receptor partial agonist, in treating schizophrenia was recently attributed to its considerably high intrinsic activity at D2 receptors. In this study, we used functional assays for recombinant D2 receptors and native 5-hydroxytryptamine 2A (5-HT2A), α2C-adrenergic, and histamine H1 receptors to compare the pharmacological properties of terguride and three of its halogenated derivatives (2-chloro-, 2-bromo-, 2-iodoterguride) with those of aripiprazole. Subsequently, we studied the antidopaminergic effects of 2-bromoterguride using amphetamine-induced locomotion (AIL). Its influence on spontaneous behavior was tested in the open field. Extrapyramidal side effect (EPS) liability was evaluated by catalepsy test. In a guanosine 5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTPγS) binding assay, 2-chloro-, 2-bromo-, and 2-iodoterguride produced intrinsic activities at human D2short (hD2S) receptors that were half as high as the intrinsic activity for terguride; aripiprazole lacked agonist activity. 2-Bromoterguride and aripiprazole activated D2S receptor-mediated inhibition of cAMP accumulation to the same extent; intrinsic activity was half as high as that of terguride. All compounds tested behaved as antagonists at human D2long/Gαo (hD2L/Gαo) receptors. Compared with aripiprazole, terguride and its derivatives displayed higher affinity at porcine 5-HT2A receptors and α2C-adrenoceptors and lower affinity at H1 receptors. 2-Bromoterguride inhibited AIL and did not induce catalepsy in rats. Because of its in vitro and in vivo properties, 2-bromoterguride may be a strong candidate for the treatment of schizophrenia with a lower risk to induce EPS.

Exaggerated aggression and decreased anxiety in mice deficient in brain serotonin

Serotonin is a major neurotransmitter in the central nervous system (CNS). Dysregulation of serotonin transmission in the CNS is reported to be related to different psychiatric disorders in humans including depression, impulsive aggression and anxiety disorders. The most frequently prescribed antidepressants and anxiolytics target the serotonergic system. However, these drugs are not effective in 20-30% of cases. The causes of this failure as well as the molecular mechanisms involved in the origin of psychological disorders are poorly understood. Biosynthesis of serotonin in the CNS is initiated by tryptophan hydroxylase 2 (TPH2). In this study, we used Tph2-deficient (Tph2(-/-)) mice to evaluate the impact of serotonin depletion in the brain on mouse behavior. Tph2(-/-) mice exhibited increased depression-like behavior in the forced swim test but not in the tail suspension test. In addition, they showed decreased anxiety-like behavior in three different paradigms: elevated plus maze, marble burying and novelty-suppressed feeding tests. These phenotypes were accompanied by strong aggressiveness observed in the resident-intruder paradigm. Despite carrying only one copy of the gene, heterozygous Tph2(+/-) mice showed only 10% reduction in brain serotonin, which was not sufficient to modulate behavior in the tested paradigms. Our findings provide unequivocal evidence on the pivotal role of central serotonin in anxiety and aggression.

Myths and facts in neuromuscular pharmacology. New developments in reversing neuromuscular blockade

Pharmacologic reversal of neuromuscular blockade is a topic not very well acknowledged and controversially discussed. Reasons for this are numerous and include missing perception of the potential complications of residual neuromuscular paralysis including an increased morbidity and mortality, as well as low efficacy and numerous unwanted side effects of the available antagonists. Duration of action of muscle relaxants cannot be pharmacologically predicted. Objective neuromuscular monitoring is the only way to detect residual paralysis. This review article would like to discuss in its first part some of the myths which revolve around the use of muscle relaxants, then highlight the problems regarding the use of acetylcholine esterase inhibitors and, in the third part, discuss the steroidal muscle relaxant encapsulator sugammadex.

[Emergency medication during pregnancy]

Medical emergencies in pregnant patients pose a great challenge. Due to a lack of experience many emergency care providers are uncertain about which drugs can be used and the dosage. The following article reviews the physiological changes during pregnancy, general considerations about pharmacotherapy in pregnant patients and highlights typical emergency scenarios with the corresponding recommendations for which drugs to use in pregnant patients.

Stimulus-dependent changes of extracellular glucose in the rat hippocampus determined by in vivo microdialysis

Neuronal activity is tightly coupled with brain energy metabolism; and glucose is an important energy substrate for neurons. The present in vivo microdialysis study was aimed at investigating changes in extracellular glucose concentrations in the rat ventral hippocampus due to exposure to the elevated plus maze. Determination of basal hippocampal glucose and lactate/pyruvate ratio in male Wistar rats was conducted in the home cage using in vivo microdialysis. Rats were exposed to the elevated plus maze, a rodent model of anxiety-related behaviour, or to unspecific stress induced by white noise (95dB) as a control condition. Basal hippocampal levels of glucose, as determined by zero-net-flux, and the basal lactate/pyruvate ratio were 1.49+/-0.05mmol/l and 13.8+/-1.1, respectively. In rats without manipulation, glucose levels remained constant throughout the experiment (120min). By contrast, exposure to the elevated plus maze led to a temporary decline in hippocampal glucose (-33.2+/-4.4%) which returned to baseline level in the home cage. White noise caused only a non-significant decrease in extracellular glucose level (-9.3+/-3.5%). In all groups, the lactate/pyruvate ratio remained unchanged by the experimental procedures. Our microdialysis study demonstrates that exposure to the elevated plus maze induces a transient decrease in extracellular hippocampal glucose concentration. In contrast, an unspecific stimulus did not change hippocampal glucose. The latter suggests that only specific behavioural stimuli increase hippocampal glucose utilization in the ventral hippocampus.

Muscle relaxant use for tracheal intubation in pediatric anaesthesia: a survey of clinical practice in Germany

OBJECTIVES

Aim of this Germany-wide study was to evaluate the use and application customs of neuromuscular blocking drugs (NMBDs) for tracheal intubation in children of age 5 years or younger.

MATERIAL AND METHODS

In the year 2005, a total of 3260 questionnaires were sent out to all heads of anesthesia departments at all types of hospitals as well as ambulatory anesthesia centers in Germany. The fields covered by the questionnaire were regarding institutional size, amount of general anesthesia and specifically pediatric cases, number of intubations and NMBDs used, frequency of use of the individual relaxants and techniques utilized when administering muscle relaxants.

RESULTS

Of the sent-out questionnaires 66.9% could be analyzed: 82% of hospitals use 1-3 muscle relaxants in children; 91% of the ambulatory anesthesia centers use a repertoire of 1-2 neuromuscular blockers for pediatric cases. However, general anesthesia with tracheal intubation in children is often induced without using any NMBD at all. Mivacurium is the predominantly used NMBD for pediatric intubation in Germany. In contrast, the use of succinylcholine is far less in ambulatory anesthesia centers than in hospitals. Despite controversial discussion, precurarization, priming, and timing are still utilized in German anesthesia practice.

CONCLUSION

In Germany, mivacurium, with its favorable pharmacologic profile for short cases, is the predominantly used NMBD for pediatric tracheal intubation. Despite the known adverse effects of intubation without muscle relaxation, this technique is also wide-spread, especially among German anesthetists in ambulatory anesthesia centers. Surveys like these are important to determine a status quo of use and application customs of NMBDs in pediatric anesthesia and provide a basis for numerous other studies.

Repeated anaesthesia with isoflurane and xylazine/levomethadone/fenpipramide premedication in female Beagle dogs: Influence on general health and wellbeing

Summary

Beagle dogs continue to be used in experimental studies and preclinical and clinical trials, many of which address the usage of anaesthesia. In order to reduce the number of animals, researchers tend to conduct several experiments on a single animal. The question arises, however, as to whether or not this frequent usage involves more than simply additional stress and discomfort for the individual animal. Within the framework of an existing study involving six female Beagle dogs, we investigated the effects of repeated (5) isoflurane anaesthesia with xylazine/levomethadone/fenpipramide premedication carried out at short intervals (2 weeks) and compared these with the effects of two treatments intermitted by a longer resting period (8 weeks). To verify our hypothesis that frequent anaesthesia affects the dog's wellbeing more than the occasional anaesthesia, the following parameters were measured at regular intervals: body weight, body temperature, respiratory rate, blood pressure, reflexes and heart rate, both at rest and during a treadmill exercise. In addition, recovery behaviour subsequent to anaesthesia was monitored for one hour. Our observations indicate that the anaesthetic effects are most prominent 24 h after the anaesthetic treatment. However, crossover analysis of our data cannot show that there is no statistical difference of whether dogs were anaesthetized occasionally or frequently. In our study, it appears that frequent anaesthesia within a two-week period did not affect the wellbeing and general health of Beagle dogs in a super-additive manner and that a minimum of two-week testing-free period is sufficient to ensure complete recovery from the unwanted effects induced by anaesthesia.