Myorelaxants of central and peripheral action

In recent years, centrally acting muscle relaxants have been widely used in clinical practice. Due to the fact that, unlike peripherally acting muscle relaxants, they do not turn off spontaneous breathing, and do not have an adverse effect on the cardiovascular system and other vital organs and systems.

The first study of centrally acting muscle relaxants was started in 1946 by Benjern Bradley. However, most of these drugs have sedative properties, and sedatives that eliminate anxiety and fear, such as sibazon, also have a central muscle relaxant effect. The exact mechanism of central muscle relaxant action is not known, although drugs of this type inhibit spinal polysynaptic reflexes and disrupt their supraspinal regulation. Some drugs also affect reticular neuronal mechanisms that control muscle tone.

Centrally acting murelaxants

Preparation	Single dose, g (tablets)
Benzodiazepines (sibazon, diazepam)	0.005-0.02
Isoprotane (carisoprodol)	0.25-0.35
Chlorzoxazone (Paraphon)	0.25-0.5
Methocarbamol (Robaxin)	0.25-0.5
Metaxalone (relaxin)	0.8
Baclofen (Lioresal)	0.01-0.03

In practice, researchers have established that myocaine, a representative of central muscle relaxants, causes a decrease in the electrical excitability of skeletal muscles for 30 minutes after administration. It also has a moderate analgesic and sedative effect. Muscle relaxation is not accompanied by unpleasant sensations, so the drug was widely used in clinical practice. In many countries, this drug is known under different names: myocaine (Austria), Mi-301 (Germany) and GGT-forte - also Germany. In 1962, F. Yu. Rachinsky and O. M. Lerner developed an identical drug - myocent (mephedol). There are more than 50 different names for mephedol.

For clinical use, mephedol is recommended to be administered intravenously as a 10% solution in 5% glucose, 20 ml at a time, or as a 20% solution, 10 ml in ampoules. In case of insufficient relaxation of the striated muscles, the dose can be increased to 40 ml of solution. The duration of action of the initial dose is 25-35 minutes. After this, if necessary, a maintenance dose is administered - 1-2 g (10-20 ml of a 10% solution of mephedol). If sediment forms in the ampoule, it is recommended to warm it up in warm water, after which the sediment disappears. Mephedol taken orally has no effect.

Absolute contraindications to the use of mephedol in clinical practice have not been established due to the insignificant toxicity of the drug and the absence of cumulation. It is not recommended to use the drug in severe cardiovascular diseases accompanied by severe hypotension. Mild dizziness and a feeling of blood rushing to the head occur extremely rarely. These sensations can be avoided by administering the drug slowly. Mephedol was approved by the Pharmacological Committee of the Ministry of Health in 1966 and is identical in chemical and pharmacological properties to the above-mentioned drugs used abroad.

The first test of the effect of mephedal on the motor function of the uterus was conducted on pregnant and non-pregnant rabbits by V. A. Strukov and L. B. Eleshina (1968). It was found that mephedol does not reduce the tone of the pregnant uterus and does not change its contractile activity. Against the background of mephedol, uterotonic drugs (pituitrin, oxytocin, pachycarpine, etc.) have their usual effect.

When using mephedol in a clinic, it was found that the drug reduces the feeling of fear, mental stress, suppresses negative emotions, thereby ensuring calm behavior of the pregnant woman and the woman in labor. In addition, in the vast majority of cases, when administering the drug, a marked decrease in the reaction to pain stimuli is noted. This is probably due to the fact that, like other central muscle relaxants, mephedol, due to the dual nature of its action, belongs to two groups of substances - muscle relaxants and tranquilizers.

Mephedol, when administered in a dose of 1 g, does not have a negative effect on the fetus and newborn, due to weak penetration through the placenta. It has been shown that mephedol in a dose of 20 ml of a 10% solution administered intravenously does not worsen hemostasis conditions in women during labor. Therefore, mephedol can be used during labor to relax the pelvic floor muscles and prevent birth trauma. This is important, since modern studies (WHO) show that the side effects of episiotomy (pain, sexual problems) can be more significant with perineal dissection than with a natural rupture.

Clinical and experimental studies have shown that mephedol is an effective remedy for treating chills due to its hypothermic effect (after abdominal surgeries, blood transfusions). A method for using mephedol was developed - at the end of the dilation period in women giving birth again or at the beginning of the expulsion period in women giving birth for the first time, i.e. 30-45 minutes before the birth of the child, a 10% solution of the centrally acting muscle relaxant mephedol (1000 mg) in a 5% glucose solution (500 mg) is slowly administered intravenously to the woman in labor. Mephedol has a selective relaxing effect on the muscles of the perineum and pelvic floor. The drug helps prevent perineal ruptures - the frequency of its damage with the use of the drug is 3 times less than in the control group. In premature births, using mephedol made it possible to avoid perineal dissection (surgical trauma) and also to prevent trauma to the head of the premature fetus due to the relaxing effect of mephedol on the muscles of the perineum and pelvic floor. Thus, the use of mephedol reduces birth trauma in the mother, helps prevent fetal and newborn trauma during normal and complicated births.

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