Scopolamine

SCOLOLAMINE, Scopolaminum, ФУП, an alkaloid, similar in chemical composition and structure to atropine and found in small quantities along with it in various plants of the nightshade family (datura, henbane, belladonna, etc.). First discovered (in impure form) in henbane and mistaken for an isomer of hyoscyamine, S. was named hyoscine (Hyoscinum), a name still occasionally used today. S., having the formula C₁₇H₂₁NO₄, is a complex ester of scopolin and tropic acid. Crystalline S. contains one molecule of water, amorphous contains none, and melts at 59°. S. is difficult to dissolve in water but easily dissolves in alcohol, ether, and chloroform. When boiled, S. decomposes into scopolin and tropic acid. Possessing significant optical activity (rotating to the left), it is inactivated by caustic alkalis, passing into a racemic form (Atroscin), which is 2-4 times less toxic than the levorotatory form. It easily forms crystalline salts with acids (of which the bromide is official), which are soluble in water with an acidic reaction. Absorption, excretion, and destruction of S. occur much faster than with atropine, which is why the pharmacological effect, appearing more quickly, also passes more quickly. The peripheral action of S. is characterized by paralysis of the endings of the parasympathetic nervous system, similar to that of atropine. Therapeutically, it is used mainly for the purpose of pupil dilation. The resorptive effect on the endings of the parasympathetic nervous system at therapeutic doses of S. is insignificant. The main difference between S. and atropine is in its effect on the central nervous system. Doses of 0.3-0.5 mg in humans cause a feeling of fatigue, reluctance to move, difficulty in speech, and unsteady gait, sometimes dizziness and headaches; then drowsiness develops, and after 7-1 hour, sleep lasting 5-8 hours occurs. Scopolamine sleep is more easily awakened than chloral sleep, and consciousness is clearer upon awakening; after awakening, the depressing effect of S. on the motor sphere lasts for several more hours, and dryness in the throat and thirst are often felt. Doses of 1-2 mg lead to mental and motor excitement. With large doses, convulsions occur, pupils dilate, and the skin becomes dry and red. Unlike atropine, scopolamine not only does not stimulate, but in large doses even depresses respiration. The most characteristic effect of scopolamine is the calming of the central nervous system, which is mainly used in therapy. Main indications: 1. States of motor excitement in mental patients. The dosage of S. in these cases is usually higher than in mentally healthy individuals. With repeated use, doses must be increased (after two weeks - doubled). In the sense of drug addiction, S. does not cause habituation. When administered during the day, S. may not reduce, but even increase excitement. 2. Hyperkinesias in paralysis agitans and postencephalitic parkinsonism (also chorea, senile tremor, etc.). In addition to suppressing convulsive movements and contractures after S., improvement in speech, weakening of salivation and lacrimation are observed. The dosage of S. in these cases is 0.4 mg subcutaneously and up to 1-2 mg per day. S. gives a better effect here than atropine, which is often used for the same indications. 3. Motion sickness. In therapy, the synergism of S. with other pharmacological agents acting on the central nervous system is sometimes used, for example: a) with ether (ether-scopolamine anesthesia); b) with opiates [morphine (0.01), pantopon (0.02)], to enhance the sedative effect or to obtain anesthesia (morphine-scopolamine anesthesia); c) with hypnotics. An enhancement of the effect is obtained when combined with substances that primarily suppress subcortical functions (luminal, pernacton), which, along with other data, confirms the view of the subcortical localization of the action of Solanaceae alkaloids. When S. is combined with hypnotics that act primarily on the cortex, the enhancement of the effect is insignificant (chloral hydrate) or absent ( paraldehyde). 4. As a mydriaticum, for example, in iritis, in doses five times smaller than atropin: one drop of a 1-2:1,000 solution. Preparations: 1) Scopolaminum hydrobromicum. Highest single dose 0.0005, highest daily 0.0015 (Ph. VII); 2) Atroscinum hydrobromicum; 3) Duboisinum - a mixture of S. and hyoscyamine. Treatment of S. poisoning according to literary data does not differ from the treatment of atropine poisoning.