Hyoscine or Scopolamine

The cholinergic hallucinogens all have common chemical constituents that are responsible for their pharmacological effects (Robbers et al. 1996). These are the tropane alkaloids hyoscyamine, scopolamine (or hyoscine), and atropine (figure 9.16). It is scopolamine, and not atropine or hyoscyamine, which primarily produces the central and hallucinogenic effects because it is the only one that passes the blood-brain barrier sufficiently. However, all three have peripheral effects. Datura stramonium contains 0.1-0.65% tropane alkaloids, which is principally... 

The alkaloids of the tropane group show a series of common chemical characteristics, particularly that of being esters of organic acids combined with bicyclic hydramines. They include Z-hyoscyamine and its isomer atropine, cocaine, scopolamine or hyoscine, and a series of secondary alkaloids. 

Antlspasmodic 2 to 3 mg/kg/day divided every 4 to 6 hours and at bedtime. SCOPOLAMINE HBr (Hyoscine HBr) Give subcutaneously or IM may give IV after dilution with Sterile Water for Injection. 

An alternative route to scopolamine and hyoscine has been reported. When tropenol is acylated with either racemic or active acetyltropoyl chloride and the respective acetyldehydroatropine or acetyldehydro-hyoscyamine is oxidized with performic acid, there is generated acetyl-scopolamine or acetylhyoscine, respectively (67b). The oxidation of scopine (LXXXIV) to scopinone (LXXXV) has been realized (133). 

When Z-scopolamine (Z-hyoscine) is warmed with barium hydroxide (52, 56, 232), dilute alkalies (232), or acids (60, 212) it is hydrolyzed to tropic acid and a new base (CsHisOjN), scopoline (oscine). Depending on the conditions of the experiment, the tropic acid recovered may be either the pure Z-form or the partially racemized acid, or may even be dehydrated to atropic acid (52, 64, 232). The scopoline isolated from these experiments is invariably optically inactive (212). By analogy with Z-hyoscyamine, Z-scopolamine would appear to be a base (scopoline) in which the alcoholic... 

Atropine and its ether analog scopolamine (hyoscine) are potent alkaloids that are found as active compounds in a large number of plants around the world (belladonna alkaloids). The deadly nightshades ( European bittersweet, Solanum dulcamara or belladonna, belladonna) were used in the Mid-... 

Hyoscine crosses the blood-brain barrier more rapidly than atropine, therefore some of the side effects are more pronounced with hyoscine. These include drowsiness, blurred vision, dizziness, dry mouth, and difficulty with micturition, while confusion may occur in the elderly. Efficacy in PONV is only moderate, and it is now rarely used. It is, however, a well-proven remedy for motion sickness, and an effect on the vestibular apparatus may contribute to its action. Here, it is given in the form of the hydrobromide (scopolamine), 1 mg of which contains 0.7 mg of the laevo-hyoscine base. Commercially available seasickness tablets usually contain 0.3 mg and one or two are recommended for protection for short journeys. Side effects preclude the long-term use of hyoscine for travel sickness. 

Atropine and its naturally occurring congeners are tertiary amine alkaloid esters of tropic acid (Figure 8-1). Atropine (hyoscyamine) is found in the plant Atropa belladonna, or deadly nightshade, and in Datura stramonium, also known as jimsonweed (Jamestown weed), sacred Datura, or thorn apple. Scopolamine (hyoscine) occurs in Hyoscyamus niger, or henbane, as the /(-) stereoisomer. Naturally occurring atropine is /(-)-hyoscyamine, but the compound readily racemizes, so the commercial material is racemic d,/-hyoscyamine. The /(-) isomers of both alkaloids are at least 100 times more potent than the d(+) isomers. 

Hyoscine (scopolamine), a prototypic muscarinic receptor antagonist, is one of the best agents for the prevention of motion sickness. However, it has a very high incidence of anticholinergic effects when given orally or parenterally. It is better tolerated as a transdermal patch. Superiority to dimenhydrinate has not been proved. 

The atropine series contains a number of very closely allied alkaloids of which the chief are atropine, hyoscyamine, and hyoscine (also called scopolamine). They are found in the roots and leaves of many plants of the Solanaceae, notably belladonna (Atropa belladonna), henbane (Hyoscyamus niger), the thorn apple or jimson weed (Datura stramonium), and some members of the Duboisia and Scopolia genera. These plants were used during the Middle Ages as sorcerer s drugs and have been smoked, chewed, or imbibed in the form of decoctions by primitive people for the hallucinations and frenzy they produce (Figure 14.1). 

Hyoscyamine (duboisine) and the racemate atropine are mACh-R antagonists and a number of atropine derivatives also have this property, namely anisodamine (6P-hydroxyhyoscyamine), 7 (3-hydroxyhyoscyamine, hyoscine (6,7-epoxyhyoscyamine or scopolamine), benzoyltropein (tropine benzoate), littorine (tropine a-hydroxyphenylpropionate), tigloidine (pseudotropane tiglate) and tropacocaine (pseudotropine benzoate). The further derivatives apoatropine (a-dehydrohyoscyamine) and tropine are very toxic. 

Atropine is the optically inactive mixture of dextro- and laevo-hyoscyamine. Laevo-hyoscyamine alone occurs in nature. The hest source of hyoscyamine is a variety of henbane indigenous in Egypt, Soudan and India, known as Hyoscyamus muticus, in the various parts of which it has been shown to be present in the following proportions leaves 1.4% stems 0.6 % seeds 0.87-1.34%. Atropine is also manufactured from the root of Scopolia carniolica, in which hyoscyamine is present to the extent of 0.43-0.51% and from A ropa belladonna, the leaves of which contain, on the average, 0.4%, and the roots 0.5%, of hyoscyamine. Many other solanaceous plants of the Datura species contain these alkaloids, in varying, and smaller, amounts, often associated with hyoscine or scopolamine. 

Hyoscine (or scopolamine) (Fig. 11.26) is also obtained from solanaceous plants and is very similar in structure to atropine. It has been used as a truth drug. 

The term anticholinergic as used in the context of this discussion refers more specifically to compounds that selectively block the brain s muscarinic receptor (now known to consist of several sub-types). Atropine (hyoscyamine) and scopolamine (hyoscine) are the most familiar medicinal anticholinergics. Historically, they were obtained from of the botanical family Solanaceae, which includes Jimson (or loco) weed, mandrake root, henbane, belladonna, and nightshade. Atropine and scopolamine are esters of tropic acid and contain a tertiary nitrogen moiety. This gives them the ability to cross the blood-brain barrier and block central muscarinic cholinergic receptors by competitive inhibition with acetylcholine, the natural neurotransmitter at these sites. 

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