Muscle relaxants potencies

Budden, R. Kuhl, V.G. Bahlsen, J. Experiments on the toxic, sedative and muscle relaxant potency of various drug solvents in mice. Pharm. Ther. Part B 1979, 5 (1-3), 467-474. 

While the individual drugs in the benzodiazepine group differ in potency, all benzodiazepines in common use have anxiolytic, sedative-hypnotic, anticonvulsant and muscle-relaxant activity in ascending order of dose. The main clinical difference between the individual drugs lies in the time of onset of their therapeutic effect, and the intensity and duration of their clinical activity. 

Benzodiazepines are highly effective anxiolytics and sedatives. They also have muscle relaxant, amnestic, and anticonvulsant properties. Benzodiazepines effectively treat both acute and chronic generalized anxiety and panic disorder. The high-potency benzodiazepines alprazolam and clonazepam have received more attention as antipanic agents, but double-blind studies also have confirmed the efficacy of diazepam and lorazepam in the treatment of panic disorder. Although only a few benzodiazepines are specifically approved by the... 

Aziz L, Ono K, Ohta Y, Morita K, Hirakawa M. The effect of C02-induced acid-base changes on the potencies of muscle relaxants and antagonism of neuromuscular block by neostigmine in rat in vitro. Anesth Analg 1994 78(2) 322-7. 

Methocarbamol was developed in 1956 in the laboratories of A.H. Robins. Studies were directed towards the development of propanediol derivatives which possessed muscle relaxant properties superior to those of mephenesin, which had low potency and a short duration of action1 >2,3. 

Alknron has the same mode of action as tubocurarine, but has 1.5-2 times its potency, the duration of action being somewhat shorter. The latency is about 30 seconds after intravenous injection and full muscle relaxation is obtained after 2-3 minntes. By individnal adaptation of doses and intervals of administration the intensity and duration of the effect can be controlled. 

According to classical structure-activity analyses with these and many other structurally related compounds, two ammonium groups, which are separated from one another by a N N distance of 14 A, represent the most important structural prerequisite for a high potency in this class of curare-like muscle relaxants (classical 14-A model). In decameth-onium iodide (150), this intramolecular N N distance is realized by a skeleton of ten carbon atoms. 

Ketamine is used as a sole anesthetic agent for diagnostic and surgical procedures that do not require skeletal muscle relaxation. It is best suited for short procedures, but it can be used with additional doses for longer procedures. It is also used for the induction of anesthesia prior to the administration of other general anesthetics and to supplement low-potency agents, such as nitrous oxide. 

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