A Novel Strategy to Reverse General Anesthesia by Scavenging with the Acyclic Cucurbit[n]uril-type Molecular Container Calabadion 2.

BACKGROUND: Calabadion 2 is a new drug-encapsulating agent. In this study, the authors aim to assess its utility as an agent to reverse general anesthesia with etomidate and ketamine and facilitate recovery. METHODS: To evaluate the effect of calabadion 2 on anesthesia recovery, the authors studied the response of rats to calabadion 2 after continuous and bolus intravenous etomidate or ketamine and bolus intramuscular ketamine administration. The authors measured electroencephalographic predictors of depth of anesthesia (burst suppression ratio and total electroencephalographic power), functional mobility impairment, blood pressure, and toxicity. RESULTS: Calabadion 2 dose-dependently reverses the effects of ketamine and etomidate on electroencephalographic predictors of depth of anesthesia, as well as drug-induced hypotension, and shortens the time to recovery of righting reflex and functional mobility. Calabadion 2 displayed low cytotoxicity in MTS-3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium-based cell viability and adenylate kinase release cell necrosis assays, did not inhibit the human ether-à-go-go-related channel, and was not mutagenic (Ames test). On the basis of maximum tolerable dose and acceleration of righting reflex recovery, the authors calculated the therapeutic index of calabadion 2 in recovery as 16:1 (95% CI, 10 to 26:1) for the reversal of ketamine and 3:1 (95% CI, 2 to 5:1) for the reversal of etomidate. CONCLUSIONS: Calabadion 2 reverses etomidate and ketamine anesthesia in rats by chemical encapsulation at nontoxic concentrations.

Reversing neuromuscular blockade: inhibitors of the acetylcholinesterase versus the encapsulating agents sugammadex and calabadion.

INTRODUCTION: Acetylcholinesterase inhibitors (neostigmine, edrophonium) and encapsulating agents (sugammadex and calabadion) can be used to reverse residual neuromuscular blockade (NMB). AREAS COVERED: This review provides information about efficacy, effectiveness, and side effects of drugs (acetylcholinesterase inhibitors and encapsulating agents) used to reverse neuromuscular blocking agents (NMBAs). EXPERT OPINION: The therapeutic range of acetylcholinesterase-inhibitors is narrow and effectiveness studies demonstrate clinicians don't use these unspecific reversal agents effectively to increase postoperative respiratory safety. The encapsulating drugs sugammadex and calabadion reverse all levels of NMB, and complete recovery of muscle strength can be achieved almost immediately after administration. For this reason encapsulating agents can be used as a solution for "cannot intubate cannot ventilate"- situations. Poor binding selectivity of encapsulating agents carries the risk of displacement of the NMBA by a competitively binding drug, which may lead to recurarization. In order to avoid side-effects, related to unspecific binding of endogenous proteins and drugs administered perioperatively it is prudent to titrate the dose of reversal agents to the minimal effective dose, depending on the depth of neuromuscular transmission block identified by neuromuscular transmission monitoring. Calabadions provide a diversified (increased binding selectivity) and expanded (reversal of benzylisoquinolines) spectrum of possible indications.

Comparative Effectiveness of Calabadion and Sugammadex to Reverse Non-depolarizing Neuromuscular-blocking Agents.

BACKGROUND: The authors evaluated the comparative effectiveness of calabadion 2 to reverse non-depolarizing neuromuscular-blocking agents (NMBAs) by binding and inactivation. METHODS: The dose-response relationship of drugs to reverse vecuronium-, rocuronium-, and cisatracurium-induced neuromuscular block (NMB) was evaluated in vitro (competition binding assays and urine analysis), ex vivo (n = 34; phrenic nerve hemidiaphragm preparation), and in vivo (n = 108; quadriceps femoris muscle of the rat). Cumulative dose-response curves of calabadions, neostigmine, or sugammadex were created ex vivo at a steady-state deep NMB. In living rats, the authors studied the dose-response relationship of the test drugs to reverse deep block under physiologic conditions, and they measured the amount of calabadion 2 excreted in the urine. RESULTS: In vitro experiments showed that calabadion 2 binds rocuronium with 89 times the affinity of sugammadex (Ka = 3.4 × 10 M and Ka = 3.8 × 10 M-). The results of urine analysis (proton nuclear magnetic resonance), competition binding assays, and ex vivo study obtained in the absence of metabolic deactivation are in accordance with an 1:1 binding ratio of sugammadex and calabadion 2 toward rocuronium. In living rats, calabadion 2 dose-dependently and rapidly reversed all NMBAs tested. The molar potency of calabadion 2 to reverse vecuronium and rocuronium was higher compared with that of sugammadex. Calabadion 2 was eliminated renally and did not affect blood pressure or heart rate. CONCLUSIONS: Calabadion 2 reverses NMB induced by benzylisoquinolines and steroidal NMBAs in rats more effectively, i.e., faster than sugammadex. Calabadion 2 is eliminated in the urine and well tolerated in rats.