Cafedrine/theodrenaline in anaesthesia: influencing factors in restoring arterial blood pressure

A fixed 20:1 combination of cafedrine/theodrenaline increases cytosolic Ca2+ concentration in human tracheal epithelial cells via ryanodine receptor-mediated Ca2+ release

Mucociliary clearance is a pivotal physiological mechanism that protects the lung by cleaning the airways from pollution and colonization, thereby preventing infection. Ciliary function is influenced by various signal transduction cascades, and Ca2+ represents a key second messenger. A fixed 20:1 combination of cafedrine and theodrenaline has been widely used to treat perioperative hypotension and emergency hypotensive states since the 1960s; however, its effect on the intracellular Ca2+ concentration ([Ca2+]i) of respiratory epithelium remains unknown. Therefore, human tracheal epithelial cells were exposed to the clinically applied 20:1 mixture of cafedrine/theodrenaline and the individual substances separately. [Ca2+]i was assessed by FURA-2 340/380 fluorescence ratio. Pharmacological inhibitors were applied to elucidate relevant signal transduction cascades, and reverse transcription polymerase chain reaction (RT-PCR) was performed on murine tracheal epithelium to analyze ryanodine receptor (RyR) subtype expression. All three pharmacological preparations instantaneously induced a steep increase in [Ca2+]i that quickly returned to its baseline value despite the persistence of each substance. Peak [Ca2+]i following the administration of 20:1 cafedrine/theodrenaline, cafedrine alone, and theodrenaline alone increased in a dose-dependent manner, with median effective concentrations of 0.35 mM (7.32 mM cafedrine and 0.35 mM theodrenaline), 3.14 mM, and 3.45 mM, respectively. When extracellular Ca2+ influx was inhibited using a Ca2+-free buffer solution, the peak [Ca2+]i following the administration of cafedrine alone and theodrenaline alone were reduced but not abolished. No alteration in [Ca2+]i compared with baseline [Ca2+]i was observed during β-adrenergic receptor inhibition. Depletion of caffeine-sensitive stores and inhibition of RyR, but not IP3 receptors, completely abolished any increase in [Ca2+]i. However, [Ca2+]i still increased following the depletion of mitochondrial Ca2+ stores using 2,4-dinitrophenol. RT-PCR revealed RyR-2 and RyR-3 expression on murine tracheal epithelium. Although our experiments showed that cafedrine/theodrenaline, cafedrine alone, or theodrenaline alone release Ca2+ from intracellular stores through mechanisms that are exclusively triggered by β-adrenergic receptor stimulation, which most probably lead to RyR activation, clinical plasma concentrations are considerably lower than those used in our experiments to elicit an increase in [Ca2+]i; therefore, further studies are needed to evaluate the ability of cafedrine/theodrenaline to alter mucociliary clearance in clinical practice.

A 20:1 synergetic mixture of cafedrine/theodrenaline accelerates particle transport velocity in murine tracheal epithelium via IP3 receptor-associated calcium release

Background: Mucociliary clearance is a pivotal physiological mechanism that protects the lung by ridding the lower airways of pollution and colonization by pathogens, thereby preventing infections. The fixed 20:1 combination of cafedrine and theodrenaline has been used to treat perioperative hypotension or hypotensive states due to emergency situations since the 1960s. Because mucociliary clearance is impaired during mechanical ventilation and critical illness, the present study aimed to evaluate the influence of cafedrine/theodrenaline on mucociliary clearance. Material and Methods: The particle transport velocity (PTV) of murine trachea preparations was measured as a surrogate for mucociliary clearance under the influence of cafedrine/theodrenaline, cafedrine alone, and theodrenaline alone. Inhibitory substances were applied to elucidate relevant signal transduction cascades. Results: All three applications of the combination of cafedrine/theodrenaline, cafedrine alone, or theodrenaline alone induced a sharp increase in PTV in a concentration-dependent manner with median effective concentrations of 0.46 µM (consisting of 9.6 µM cafedrine and 0.46 µM theodrenaline), 408 and 4 μM, respectively. The signal transduction cascades were similar for the effects of both cafedrine and theodrenaline at the murine respiratory epithelium. While PTV remained at its baseline value after non-selective inhibition of β-adrenergic receptors and selective inhibition of β1 receptors, cafedrine/theodrenaline, cafedrine alone, or theodrenaline alone increased PTV despite the inhibition of the protein kinase A. However, IP3 receptor activation was found to be the pivotal mechanism leading to the increase in murine PTV, which was abolished when IP3 receptors were inhibited. Depleting intracellular calcium stores with caffeine confirmed calcium as another crucial messenger altering the PTV after the application of cafedrine/theodrenaline. Discussion: Cafedrine/theodrenaline, cafedrine alone, and theodrenaline alone exert their effects via IP3 receptor-associated calcium release that is ultimately triggered by β1-adrenergic receptor stimulation. Synergistic effects at the β1-adrenergic receptor are highly relevant to alter the PTV of the respiratory epithelium at clinically relevant concentrations. Further investigations are needed to assess the value of cafedrine/theodrenaline-mediated alterations in mucociliary function in clinical practice.

[Vasopressors: Physiology, Pharmacology and Clinical Applications]

Vasopressors are widely used in anaesthesiology and critical care medicine, to treat harmless (e.g. anaesthesia-induced hypotension) as well as life-threatening conditions (e.g. septic shock). Some clinically used vasopressors resemble endogenous substances - such as norepinephrine - while others have been artificially synthesized (e.g. phenylephrine). Most of the substances used in different clinical scenarios have various effects except for vasoconstriction alone. Therefore, a thorough understanding of the pharmacology and clinical profile of every single substance is of highest importance prior to practical usage. Furthermore, the fundamentals of vascular physiology and vasotonic regulation are mandatory to safely provide vasopressor-based therapies. This article covers the essentials of physiology and pharmacology of vasopressors, and the clinical settings they are used in (e.g. septic shock, vasoplegic shock after cardiac surgery, trauma-induced hypotension).

Treatment of intraoperative hypotension with cafedrine/theodrenaline versus ephedrine : A prospective, national, multicenter, non-interventional study-the HYPOTENS trial

BACKGROUND

Sympathomimetic drugs are a therapeutic cornerstone for the management of hypotensive states like intraoperative hypotension (IOH). While cafedrine/theodrenaline (C/T) is widely used in Germany to restore blood pressure in patients with IOH, more research is required to compare its effectiveness with alternatives such as ephedrine (E) that are more commonly available internationally.

METHODS

HYPOTENS (NCT02893241, DRKS00010740) was a prospective, national, multicenter, open-label, two-armed, non-interventional study that compared C/T with E for treatment of IOH. We describe a prospectively defined cohort of patients ≥50 years old with comorbidities undergoing general anesthesia induced with propofol and fentanyl. Primary objectives were to examine treatment precision, rapidity of onset and the ability to restore blood pressure without relevant increases in heart rate. Secondary endpoints were treatment satisfaction and the number of required additional boluses or other accompanying measures.

RESULTS

A total of 1496 patients were included in the per protocol analysis. Overall, effective stabilization of blood pressure was achieved with both C/T and E. Post-hoc analysis showed that blood pressure increase from baseline was more pronounced with C/T. Fewer additional boluses or other accompanying measures were required in the C/T arm. The incidence of tachycardia was comparable between groups. Post-hoc analysis showed that E produced dose-dependent elevated heart rate values. By contrast, heart rate remained stable in patients treated with C/T. Physicians reported a higher level of treatment satisfaction with C/T, with a higher proportion of anesthetists rating treatment precision and rapidity of onset as good or very good when compared with E.

CONCLUSION

Neither drug was superior in restoring blood pressure levels; however, post-hoc analyses suggested that treatment is more goal-orientated and easier to control with C/T. Heart rate was shown to be more stable with C/T and fewer additional interventions were required to restore blood pressure, which could have contributed to the increased treatment satisfaction reported by anesthetists using C/T.

Crystalloid coloading vs. colloid coloading in elective Caesarean section: postspinal hypotension and vasopressor consumption, a prospective, observational clinical trial

BACKGROUND

Maternal hypotension is a common side effect of spinal anaesthesia for Caesarean section. The combination of colloid coloading and vasopressors was considered our standard for its prevention and treatment. As the safety of hydroxyethyl starch is under debate, we replaced colloid with crystalloid coloading.

OBJECTIVE

We hypothesize that the mean blood pressure drop is greater when coloading with crystalloids.

DESIGN

Prospective, observational clinical trial.

SETTING

Two-centre study conducted in Berlin, Germany.

PATIENTS

Parturients scheduled for a Caesarean section were screened for eligibility.

INTERVENTION

The study protocol and patient monitoring were based on the standard operating procedure for Caesarean section in both centres. The data from the crystalloid group were prospectively collected between November 2014 and July 2015.

MAIN OUTCOME MEASURES

The primary endpoint was the median drop in mean blood pressure after induction of spinal anaesthesia. Secondary endpoints were incidence of hypotension (drop > 20% of baseline systolic pressure /drop < 100 mmHg), vasopressor and additional fluid requirements (mL), incidence of bradycardia (heart rate < 60 beats per minute), blood loss, Apgar score, and umbilical artery pH. In case of hypotension, patients received phenylephrine or cafedrine/theodrenaline according to their heart rate. A p < 0.05 was considered significant.

RESULTS

345 prospectively enrolled patients (n = 193 crystalloid group vs. n = 152 colloid group) were analysed. The median drop in mean blood pressure was greater in the crystalloid group [34 mmHg (25; 42 mmHg) vs. 21 mmHg (13; 29 mmHg), p < 0.001]. Incidences of hypotension [93.3% vs. 83.6%, p: 0.004] and bradycardia [19.7% vs. 9.9%, p: 0.012] were also significantly greater in the crystalloid group. Vasopressor requirements, blood loss and neonatal outcome were not different between the groups.

CONCLUSIONS

Crystalloid coloading was associated with a greater drop in mean blood pressure and a higher incidence of hypotension when compared with colloid coloading. Neonatal outcome was, however, unaffected by the type of fluid.

TRIAL REGISTRATION

DRKS00006783 ( http://www.drks.de ).

A non-interventional comparative study of the 20:1 combination of cafedrine/theodrenaline versus ephedrine for the treatment of intra-operative arterial hypotension: the 'HYPOTENS' study design and rationale

OBJECTIVE

To compare the effectiveness of 20:1 cafedrine/theodrenaline approved for use in Germany to ephedrine in the restoration of arterial blood pressure and on post-operative outcomes in patients with intra-operative arterial hypotension of any origin under standard clinical practice conditions.

METHODS AND RESULTS

'HYPOTENS' is a national, multi-center, prospective, open-label, two-armed, non-interventional study. Effectiveness and post-operative outcome following cafedrine/theodrenaline or ephedrine therapy will be evaluated in two cohorts of hypotensive patients. Cohort A includes patients aged ≥50 years with ASA-classification 2-4 undergoing non-emergency surgical procedures under general anesthesia. Cohort B comprises patients undergoing Cesarean section under spinal anesthesia. Participating surgical departments will be assigned to a treatment arm by routinely used anti-hypotensive agent. To minimize bias, matched department pairs will be compared in a stratified selection process. The composite primary end-point is the lower absolute deviation from individually determined target blood pressure (IDTBP) and the incidence of heart rate ≥100 beats/min in the first 15 min. Secondary end-points include incidence and degree of early post-operative delirium (cohort A), severity of fetal acidosis in the newborn (cohort B), upper absolute deviation from IDTBP, percentage increase in systolic blood pressure, and time to IDTBP.

CONCLUSION

This open-label, non-interventional study design mirrors daily practice in the treatment of patients with intra-operative hypotension and ensures full treatment decision autonomy with respect to each patient's individual condition. Selection of participating sites by a randomization process addresses bias without interfering with the non-interventional nature of the study. First results are expected in 2018. ClinicalTrials.gov identifier: NCT02893241; DRKS identifier: DRKS00010740.

Vaccine-driven pharmacodynamic dissection and mitigation of fenethylline psychoactivity

Fenethylline, also known as Captagon, is a synthetic psychoactive stimulant that has recently been linked to substance use disorder and ‘pharmacoterrorism’ in the Middle East.^1–4 Although fenethylline shares a common phenethylamine core with other amphetamine-type stimulants, it additionally incorporates a covalently-linked xanthine moiety into its parent structure.^5,6 These independently-active pharmacophores are liberated during metabolism, resulting in a structurally-diverse chemical mixture being deployed to the central nervous system.^7–9 Although fenethylline’s psychoactive properties have been reported to differ from other synthetic stimulants, the in vivo chemical complexity it manifests upon ingestion has impeded efforts to unambiguously identify the specific species responsible for these effects.^10,11 Here we develop a ‘dissection through vaccination’ approach, called DISSECTIV, to mitigate fenethylline’s psychoactivity and show that its rapid-onset and distinct psychoactive properties are facilitated by functional synergy between theophylline and amphetamine. Our results demonstrate that incremental vaccination against single chemical species within a multi-component mixture can be used to uncover emergent properties arising from polypharmacologic activity. We anticipate that DISSECTIV will be employed to expose unidentified active chemical species and illuminate pharmacodynamic interactions within other chemically complex systems, such as those found in counterfeit or illegal drug preparations, post-metabolic tissue samples, and natural product extracts.

AkrinorTM, a Cafedrine/ Theodrenaline Mixture (20:1), Increases Force of Contraction of Human Atrial Myocardium But Does Not Constrict Internal Mammary Artery In Vitro

Background: Intraoperative hypotension is a common problem and direct or indirect sympathomimetic drugs are frequently needed to stabilize blood pressure. Akrinor^TM consists of the direct and the indirect sympathomimetic noradrenaline and norephedrine. Both substances are covalently bound to the phosphodiesterase (PDE) inhibitor theophylline, yielding theodrenaline and cafedrine, respectively. We investigated pharmacodynamic effects of Akrinor^TM and its constituents on contractile force and tension in human atrial trabeculae and internal A. mammaria rings.

Methods: Isometric contractions were measured in human atrial trabeculae at 1 Hz and 37°C. CGP 20712A and ICI 118,551 were used to elaborate β₁- and β₂-adrenoceptor (AR) subtypes involved and phenoxybenzamine to estimate indirect sympathomimetic action. PDE-inhibition was measured as a potentiation of force increase upon direct activation of adenylyl cyclase by forskolin. Human A. mammaria preparations were used to estimate intrinsic vasoconstriction and impact on the noradrenaline-induced vasoconstriction.

Results: Clinically relevant concentrations of Akrinor^TM (4.2–420 mg/l) robustly increased force in human atrial trabeculae (EC₅₀ 41 ± 3 mg/l). This direct sympathomimetic action was mediated via β₁-AR and the effect size was as large as with high concentrations of calcium. Only the highest and clinically irrelevant concentration of Akrinor^TM increased the potency of forskolin to a minor extent. Norephedrine has lost its indirect sympathomimetic effect when bound to theophylline. Increasing concentrations of Akrinor^TM (4.2–168 mg/l) alone did not affect the tension of human A. mammaria interna rings, but shifted the noradrenaline curve rightward from -logEC₅₀ 6.18 ± 0.08 to 5.23 ± 0.05 M.

Conclusion: Akrinor^TM increased cardiac contractile force by direct sympathomimetic actions and PDE inhibition, did not constrict A. mammaria preparations, but shifted the concentration-response curve to the right, compatible with an α-AR antagonistic effect or PDE inhibition. The pharmacodynamic profile and potency of Akrinor^TM differs from noradrenaline and norephedrine in vitro. We anticipate metabolism of theodrenaline and cafedrine resulting in a different pharmacodynamic profile of Akrinor^TMin vivo.

Cafedrine/Theodrenaline (20:1) Is an Established Alternative for the Management of Arterial Hypotension in Germany-a Review Based on a Systematic Literature Search

A 20:1 combination of cafedrine:theodrenaline (Akrinor®) is widely used in Germany for the treatment of hypotensive states during anesthesia and in emergency medicine. Although this drug formulation has been available since 1963, there are few studies relating to its use and many of the data are only available in German. In this article, we summarize the available data and propose mechanisms for the effects of cafedrine/theodrenaline on cardiac muscle cells and vascular smooth muscle cells. Cafedrine/theodrenaline leads to a rapid increase in mean arterial pressure that is characterized by increased cardiac preload, stroke volume, and cardiac output. Systemic vascular resistance and heart rate remain mostly unchanged. Factors which impact the effects of cafedrine/theodrenaline are gender, high arterial pressure at baseline, use of β-blockers, and heart failure. Importantly, the drug is frequently used in obstetric anesthesia without detrimental effects on umbilical cord pH or APGAR score.

[Epidural anesthesia for fetoscopy : Retrospective analysis of a one-year cohort]

BACKGROUND

The introduction of routine prenatal screening using ultrasound has led to a substantial increase in diagnoses of fetal disorders that are amenable to intrauterine treatment. While an ultrasound guided insertion of small bore cannulas can be performed under local anesthesia, insertion of a fetoscope usually requires anesthetic management for the mother and the fetus. Additionally, the fetus' intrauterine position may have to be manipulated in order to enable access. Such manoeuvres depend on relaxation of the mother's abdominal wall. General anesthesia has been the preferred method, but it involves substantial risks both to the mother and possibly the fetus, especially when combined with aggressive uterine relaxation. Epidural anesthesia (EA) may provide an alternative. Only little systematic data on the efficacy, requirements or untoward effects of epidural anesthesia for fetoscopy exists in the literature, yet a high rate of arterial hypotension following EA has been reported. We therefore aimed to assess the hemodynamic reaction to EA in a mixed population of pregnant women undergoing fetoscopy for a variety of fetal conditions and performed a retrospective analysis of a one-year cohort in a single university hospital.

METHODS

The local ethics committee approved this retrospective analysis and waived patient consent (local study identifier 304/14). We extracted anesthesiologic and hemodynamic data from the anesthesia charts of 23 consecutive cases of elective fetoscopic procedures requiring anesthesia between May 2011 and 2012 at a German university medical centre.

RESULTS

Twenty-three cases of fetoscopy were included in this study. Indications for fetoscopy were congenital diaphragmatic hernia (n = 9), aortic valve stenosis (n = 8), and feto-fetal transfusion syndrome (n = 6). Median gestational age was 26 (8, interquartile range) weeks. Lumbar epidural catheters were injected with a median dose of 0.09 (0.02, interquartile range) ml ropivacaine 0.75% per cm maternal height. In 11 patients, EA was titrated to a sufficient height whereas 12 patients received a single dose with a median volume of 0.08 (0.02) ml/cm maternal height. After injection, systolic arterial pressure did not change significantly, mean arterial pressure dropped from 93 (14) mm Hg to 88 (15) mm Hg (p = 0.03). Heart rate fell from 96 (29) to 89 (20) beats per minute (p = 0.02). At incision, neither blood pressure nor heart rate changed significantly. For hemodynamic support during the procedure, cafedrine/theodrenaline (Akrinor™) was injected in five patients (median dose in these patients 0.5 (1.5) ml). One patient carrying a fetus with a poor prognosis and who underwent two separate procedures demanded additional sedation, for which we chose remifentanil. Another patient was hypotensive after intravenous administration of the tocolytic drug atosiban. A stable hemodynamic condition was quickly restored in this patient with administration of cafedrine/theodrenaline and i. v. fluids. All procedures were performed without conversion to general anaesthesia.

CONCLUSION

This retrospective study demonstrates that fetoscopic procedures under EA in the range of indications treated in our institution can be performed safely. EA was associated with stable hemodynamic conditions in this mixed cohort of pregnant women. EA appears thus to be a suitable technique for fetoscopy, avoiding the risks inherent to general anesthesia in pregnant women.