Analgesics

Promedol (trimeperidine hydrochloride). Promedol, as is known, is a synthetic substitute for morphine and has a pronounced analgesic effect. Reduction of pain sensitivity under the influence of promedol develops after subcutaneous injection after 10-15 minutes. The duration of analgesia is 3-4 hours. The maximum permissible single dose of promedol in labor is 40 mg (2% solution - 2 ml) subcutaneously or intramuscularly. When combined with neuroleptic drugs, the effect of promedol is enhanced.

According to numerous clinical and experimental data, promedol enhances uterine contractions. It was established in the experiment that stimulating effect of promedol on the smooth muscles of the uterus and recommended its application simultaneously for anesthesia and enhancement of labor. Has a pronounced antispasmodic and rhodocoating properties.

Estozin - a synthetic analgesic, along with cholino and spasmolytic, also has a pronounced analgesic effect. Thus the anesthetic effect develops quickly enough at any way of introduction of a preparation (inside, intramuscularly or intravenously), however duration of an analgesic effect does not exceed hour.

The analgesic effect of estocin is about 3 times slower than promedol, but it is less toxic than promedol. Estotin less depresses breathing, does not increase the tone of the vagus nerve; has moderate spasmolytic and holinoliticheskoe effect, reduces spasms of the intestines and bronchi; does not cause constipation. In obstetric practice is used internally in doses of 20 mg.

Pentazocine (lexine, fortral) has a central analgesic effect, the intensity of which almost reaches the action of opiates, but does not cause depression of the respiratory center and other side effects, addiction and predilection. The analgesic effect occurs 15-30 minutes after intramuscular injection and lasts about 3 hours. The lexicon has no effect on the motor function of the gastrointestinal tract, excretory organs, sympathetic-adrenal system and causes a mild short-term cardiostimulating effect. Teratogenic effect is not described, but it is not recommended to administer the drug in the first trimester of pregnancy, is administered at a dose of 0.03 g (30 mg), and for severe pains 0.045 g (45 mg) intramuscularly or intravenously.

Fentanyl is a derivative of piperidine, but the strength of the analgesic effect exceeds morphine in 200, and promedol - 500 times. Has a pronounced depressor effect on the respiratory center.

Fentanyl causes selective blockade of some adrenergic structures, resulting in a decrease in the reaction to catecholamines after its administration. Fentanyl is used at a dose of 0.001-0.003 mg per 1 kg of body weight of the parturient (0.1-0.2 mg - 2-4 ml of the drug).

Dipidolor. It was synthesized in 1961 in the laboratory of Janssen. On the basis of pharmacological experiments, it has been established that dipidolor is two times more powerful than morphine in its analgesic activity and 5 times that of pethidine (promedol).

The toxicity of dipidolor is extremely low - subacute and chronic toxicity this drug does not possess. The therapeutic breadth of dipidolor is 1 / times times that of morphine, and 3 times that of pethidine (promedol). The drug does not have a negative effect on the liver, kidneys, cardiovascular system, does not change the electrolyte balance, thermoregulation, the state of the sympathetic-adrenal system.

With intravenous administration, the effect of dipidolor is not immediately apparent, but with intramuscular, subcutaneous and even oral administration, after 8 minutes; the maximum effect develops after 30 minutes and lasts from 3 to 5 hours. In 0.5% of cases, nausea occurs, vomiting was not noted. A reliable antidote is nalorfin.

Ataralgesia dipidolorom and seduxenom has potentiated synergism. The analgesic activity of the combination is greater than the sum of the effects of analgesia with separate use of dipidolor and seduxen in the same doses. The degree of neurovegetative protection of the body increases with a combination of dipidolor and seduksen by 25-29%, and respiratory depression is significantly reduced.

The basis of the modern anesthetic tool is combined analgesia, which creates conditions for directed regulation of body functions. Studies show that the problem of anesthesia is increasingly evolving into a purposeful correction of pathophysiological and biochemical changes.

Dipidolor is usually injected intramuscularly and subcutaneously. Intravenous administration is not recommended because of the risk of respiratory depression. Taking into account the pain intensity, age and general condition of the woman, the following doses are used: 0.1-0.25 mg per 1 kg of the mass of the mother giving birth - an average of 7.5-22.5 mg (1-3 ml of the drug).

Like all morphine-like substances, dipidolor inhibits the center of breathing. With intramuscular injection of the drug in therapeutic doses, respiratory depression is extremely limited. It occurs usually in exceptional cases only with an overdose or hypersensitivity to the patient. The respiratory depression quickly stops after intravenous administration of a specific antidote, naloxone (nalorphine) in a dose of 5-10 mg. Antidote can be administered intramuscularly or subcutaneously, but then its effect comes more slowly. Contraindications are the same as for morphine and its derivatives.

Ketamine. The drug is issued in the form of a stabilized solution in 10 and 2 ml vials containing respectively 50 and 10 mg of the drug in 1 ml of a 5% solution.

Ketamine (calypsole, ketalar) is a low-toxic drug; acute toxic effects occur only with more than 20-fold overdose; does not cause local tissue irritation.

The drug is a strong anesthetic. Its use causes a deep somatic analgesia, sufficient for performing cavitary surgical interventions without the use of additional anesthesia. The specific condition in which the patient is in anesthesia is called selective "dissociative" anesthesia, in which the patient seems more likely to be "disconnected" than to the sleeper. For small surgical interventions, intravenous drip application of subnarcotic doses of ketamine (0.5-1.0 mg / kg) is recommended. In this case, surgical anesthesia in many cases is achieved without deenergizing the patient's consciousness. The use of standard doses of ketamine (1.0-3.0 mg / kg) leads to the preservation of residual postoperative analgesia, which allows completely eliminating or significantly reducing the amount of injected drugs within 2 hours.

It should be noted a number of adverse effects of ketamine: the appearance of hallucinations and excitation in the early postoperative period, nausea and vomiting, seizures, accommodation disorders, spatial disorientation. In general, such phenomena occur in 15-20% of cases when using the drug in a "pure" form. They are usually short (several minutes, rarely - tens of minutes), their severity is rarely significant, and in most cases there is no need to prescribe a special therapy. The number of such complications can be almost reduced to zero by the introduction of premedication drugs benzodiazepine series, central neuroleptics. The administration of diazepam (eg, 5-10 mg for short-term surgery, 10-20 mg for prolonged surgery) or droperidol (2.5-7.5 mg) prior to and / or during surgery, almost always eliminates "awakening reactions" . The emergence of these reactions can be largely prevented if we restrict sensory afferent flows, that is, close our eyes in the awakening phase, avoid premature personal contact with the patient, and also talk and touch to the patient; they do not happen also with the combined use of ketamine together with inhaled narcotic substances.

Ketamine is rapidly and evenly distributed in the body in virtually all tissues, and its concentration in the blood plasma is reduced by an average of 10 minutes. The half-life of the drug in the tissues is 15 minutes. Due to the rapid inactivation of ketamine and its low content in the fat stores of the body, cumulative properties are not expressed.

The most intensive metabolism of ketamine occurs in the liver. The cleavage products are removed mainly with urine, although other ways of elimination are possible. The drug is recommended to use intravenously or intramuscularly. With intravenous administration, the initial dose is 1-3 mg / kg of body weight, narcotic sleep occurs on average in 30 seconds. An intravenous dose of 2 mg / kg is usually sufficient for anesthesia within 8-15 minutes. With intramuscular administration, the initial dose is 4-8 mg / kg, with surgical pain relief achieved in 3-7 minutes and lasts from 12 to 25 minutes.

Induction of anesthesia occurs quickly and, as a rule, without excitement. In rare cases, a short and mild tremor of the extremities and tonic contraction of the facial muscles are observed. Maintenance of anesthesia is carried out by repeated intravenous administration of ketamine at a dose of 1-3 mg / kg every 10-15 minutes of operation or by intravenous administration of ketamine with a drop rate of 0.1-0.3 mg / kg-min. Ketamine is well combined with other anesthetics and can be used with the addition of narcotic analgesics, inhaled narcotic drugs.

Self-breath on the background of anesthesia is maintained at a sufficiently effective level when using clinical doses of the drug; only a significant overdose (3-7 times) can lead to a depressed respiration. Very rarely, with intravenous rapid administration of ketamine, a short-term apnea occurs (a maximum of 30-40 seconds), which, as a rule, does not require special therapy.

The effect of ketamine on the cardiovascular system is associated with the stimulation of a-adrenoreceptors and the release of norepinephrine from peripheral organs. The transient character of the changes in blood circulation with the use of ketamine does not require special therapy and these changes are short (5-10 min).

Thus, the use of ketamine allows anesthesia to be performed against the background of self-contained respiration; the risk of aspiration syndrome is much lower.

In the literature there are quite conflicting data on the effect of ketamine on the contractile activity of the uterus. This is probably due to both the concentration of anesthetic in the blood, and the tone of the autonomic nervous system.

Currently, ketamine is used as an introductory anesthesia for a caesarean section, as a mononarcosis for providing abdominal delivery and "small" obstetric surgeries, as well as for analgesia of labor during intramuscular administration of the drug with the aid of drop perfusion.

Some authors use a combination of ketamine with diazepam or 2 ml synthodian, which is equivalent to 5 mg of droperidol with ketamine intramuscularly at a dose of 1 mg / kg.

E. A. Lantsev et al. (1981) developed methods for anesthetizing labor, anesthesia, ketamine anesthetics on the background of artificial ventilation of the lungs or independent breathing, and anesthesia of small obstetrical operations with ketamine. The authors concluded that ketamine has a relatively small number of contraindications. These include - the presence of late toxicosis of pregnant women, pshtretenzii various etiologies in the large and small circles of blood circulation, psychiatric illness in the anamnesis. Bertoletti et al. (1981) indicate that intravenous administration of 250 mg of ketamine per 500 ml of a 5% solution of glucose in 34% of women giving birth showed a slowing of the rate of uterine contractions, which was correlated with the administration of oxytocin. Methfessel (1981) investigated the effects of ketamine monoanesthesia, ketamine-seduxene anesthesia, and ketamine monoanesthesia, with preliminary preparation of tocoliths (partusen, dilatol) for intrauterine pressure. It has been established that the preliminary administration (prophylactically) of partusisten significantly reduces the effect of ketamine on intrauterine pressure. In conditions of combined ketamine-seduxene anesthesia, this undesirable effect is completely blocked. In an experiment on rats, ketamine only slightly modifies the reactivity of the myometrium to bradykinin, but is the cause of a gradual loss of the sensitivity of rat myometrium to prostaglandin.

Caloxto et al. Also in experiments with an isolated rat uterus, in order to elucidate the mechanism of action of ketamine, its inhibitory effect on the myometrium has been shown, evidently due to the inhibition of Ca ²⁺ transport . Other authors in the clinic did not reveal the inhibitory effect of ketamine on the myometrium, as well as on the course of labor.

Negative effects of ketamine on the condition of the fetus and the newborn child were not revealed both in the anesthetization of labor and during operative delivery, there was no effect of ketamine on the cardiotocogram indicators and the acid-base state of the fetus and newborn.

Thus, the use of ketamine extends the arsenal of means for providing a cesarean section operation, anesthesia of labor using various techniques.

Butorphanol (moradol) - is a strong analgesic for parenteral use and is close in action to pentazocine. On the strength and duration of the action, the speed of the onset of the effect is close to morphine, but is effective in smaller doses; The dose of moradol 2 mg causes strong analgesia. Since 1978, moradol has been widely used in clinical practice. The drug penetrates the placenta with minimal effect on the fetus.

Moradol is injected intramuscularly or intravenously in a dosage of 1-2 ml (0.025-0.03 mg / kg) with persistent pain and cervical dilatation of 3-4 cm. The analgesic effect is obtained in 94% of parturient women. With intramuscular injection, the maximum effect of the drug was observed after 35-45 minutes, and with intravenous - in 20-25 minutes. The duration of analgesia was 2 hours. There was no adverse effect of Moradol in the dosages applied on the fetal condition, contractile activity of the uterus and the state of the newborn.

When using the drug should be careful in patients with high blood pressure.

Tramadol (tramal) - has a strong analgesic activity, gives a quick and lasting effect. Inferior, however, to the activity of morphine. When administered intravenously, it has an analgesic effect after 5-10 minutes, when administered intravenously, after 30-40 minutes. Effective for 3-5 hours. Intravenously injected at a dose of 50-100 mg (1-2 ampoules, up to 400 mg, 0.4 g) per day. In the same dose administered intramuscularly or subcutaneously. Negative impact on the maternity of the mother, contractile activity of the uterus is not revealed. An increased amount of meconium admixture in the amniotic fluid was noted, without changing the character of the fetal heartbeat.

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