Classifications
Fazal-I-Akbar Danish, Ahmed Ehsan Rabbani in Pharmacology in 7 Days for Medical Students, 2018
Neuromuscular blocking agentsCompetitive blocking/nondepolarising agentsAlcuroniumAtracuriumDimethyl tubocurarineFazadiniumGallaminePancuroniumTubocurarineVecuroniumDepolarising agentsDecamethoniumSuxamethoniumSuxemethonium
Therapies
Marc H. De Baets, Hans J.G.H. Oosterhuis in Myasthenia Gravis, 2019
Myasthenic weakness may worsen after surgery. Depolarizing neuromuscular blocking agents should not be used. Even low doses may lead to pronounced and long-lasting neuromuscular block. If application of a neuromuscular blocking agent is necessary, a nondepolarizing curare-like relaxant, such as alcuronium, vecuronium, or atracurium, is used at one tenth to one half the normal dose.113 It should be anticipated that patients with myasthenia occasionally require assisted respiration for longer than normal after surgery, even if myasthenia has been treated successfully before the operation. Assisted respiration is continued until the patient is able to cooperate and demonstrates adequate respiratory function. A detailed discussion of pre- and postoperative care of the myasthenic patient may be found in reference 114.
General anaesthesia and failure to ventilate
Daryl Dob, Griselda Cooper, Anita Holdcroft, Philip Steer, Gwyneth Lewis in Crises in Childbirth Why Mothers Survive, 2018
This obese woman had had a previous ineffective epidural for pregnancy. However, during this labour she had an effective epidural that had not been topped up for 2 hours, which implies that the epidural was probably working. As she failed to progress, a Caesarean section was planned, for which there was no particular urgency. The top-up for the epidural did not work, indicating that the catheter had probably fallen out. It is sensible for the anaesthetist to check the position of the catheter before providing a top-up. As this patient was obese, it would now be worth considering a spinal anaesthetic, although at the time this was a less common procedure. Assessment of her airway should have been properly carried out and an appropriate airway plan developed. This general anaesthetic was made more difficult by the absence of skilled help. The patient became hypoxic when further paralysis was provided by alcuronium. Although after the endotracheal tube was removed, oxygenation was successfully provided with a bag and mask, the patient died 2 weeks later. The case is made all the more poignant by the fact that the obstetrician delivered the baby by breech extraction, which implies that the Caesarean section was an unnecessary operation.
Effect of cardiopulmonary bypass on cytochrome P450 enzyme activity: implications for pharmacotherapy
Published in Drug Metabolism Reviews, 2018
Santosh Kumar Sreevatsav Adiraju, Kiran Shekar, John F. Fraser, Maree T. Smith, Sussan Ghassabian
On the other hand, drugs that are not metabolized by liver are affected to a smaller extent compared with the previous group. Vancomycin, rocuronium, doxacurium, and alcuronium are drugs with low plasma protein binding (30–70% to albumin) and that are eliminated from the body unchanged in the urine (vancomycin (Zhao et al. 2014), teicoplanin (Roberts et al. 2014), daptomycin (Dvorchik et al. 2003)) or urine and bile (alcuronium (Miller et al. 1997), rocuronium (Khuenl-Brady and Sparr 1996), doxacurium (Cook et al. 1991; Asokumar et al. 1998)). A 20% increase in vancomycin CL with no change in t½β (Ortega et al. 2003) was underpinned by a 30% decrease in vancomycin renal CL during CPB which returned to the pre-CPB levels after CPB termination (Klamerus et al. 1988). Similarly, a 38% decrease in doxacurium t½β1/2 in hypothermic compared with normothermic CPB has been reported (Asokumar et al. 1998). The impact of CPB on the renal CL of drugs can be explained by two opposing factors: reduced kidney perfusion and reduced plasma protein binding. Teicoplanin and daptomycin are eliminated by the kidney (Dvorchik et al. 2003; Roberts et al. 2014), but have high plasma protein binding (Lee et al. 1991; Yano et al. 2007; Beer et al. 2009) with both factors potentially affected by initiation of CPB therapy. Altered plasma protein binding of important drugs is thought to be underpinned by changes in acid-base balance during CPB (Gedney and Ghosh 1995). Tranexamic acid is a drug with only 3% plasma protein binding and small metabolism (McCormack 2012) and its PK was not affected during cardiac surgery using CPB (Table 1).
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