Difference in names
Hyoscyamine is also known as Daturine and is one of the secondary metabolites found in the Solanaceae plant family. Hyoscine is also called as Scopolamine. They are the two main derivatives of the plant Hyoscyamus whose botanical name is Hyoscyamus Niger. They are one of the members of the Trophane alkaloids where as the Coca alkaloids are another set of Trophane alkaloids found in the plant.
Difference in chemical structure
The chemical structure of Hyoscyamine is C-17, H-23, NO3 whereas hyoscine has the structure C-17, H-21, NO4. . Hyoscyamine is a pure optical isomer and is given the (+) or the delta form where as the alkaloid Hyoscine is given the (-) sign or the levo form. It can be said that Hyoscyamine is a racemic form of Atropine.
Pathway of working
Hyoscyamine acts by blocking the cholinergic receptors and reduces muscle movement whereas hyoscine is only a selective receptor blocker and will not affect all receptors.
Difference in working
Hyoscyamine and hyoscine both act on the salivatory and sweat producing organs of the body, but hyoscine is more powerful in action compared to Hyoscyamine. It is also noticed that both produce sedation when used as anesthetics but hyoscine can cause amnesia (loss of memory) in some patients.
Hyoscyamine is more potent than Hyoscine to increase the heart rate when given intravenously. Small doses of hyoscine will cause central nervous toxicity whereas to have the same effect, continuous high doses of Hyoscyamine are required. This proves that hyoscine is very fatal even in minor doses whereas extremely high doses of Hyoscyamine are required to produce the same kind of depression of the central nervous system.
Whenever hyoscine is given as anesthesia in pre-operative cases, there is a high risk that the patient will have delirium post-operatively but there is very little risk after administering Hyoscyamine.
Hyoscine produces respiratory depression rapidly once it is administered but to have the same effect on the respiratory muscles much higher quantities of Hyoscyamine need to be injected and the changes take place after comparatively longer durations. Hyoscine is quicker in action and fatal in smaller doses when compared with Hyoscyamine.
Difference in indications:
Hyoscine is used to treat opium withdrawal symptoms after a person has kicked the habit of opium. Hyoscine was earlier used as truth serum as for extracting truth from criminals in the jail. The reason behind this was the deep state of intoxication that the drug produced such that the criminal was not in a state of mind to frame a lie when questioned. Thus it achieved fame as the ‘truth serum’.
Adverse effects of hyoscyamine and hyoscine
Hyoscyamine overdose causes dryness of mouth and throat, eye pain, blurred vision, restlessness, dizziness, arrhythmia, flushing, and faintness but hyoscine produces symptoms of memory loss and dizziness and central nervous system depression if the patient is overdosed. Hyoscyamine is a very potent anti-muscarinic receptor. The euphoric and sexual adverse effects of Hyoscyamine are stronger and more pronounced than in hyoscine.
Hyoscine is a stronger central nervous depressant and amnesic whereas hyoscyamine is more excitatory as compared to hyoscine. Hyoscyamine also called as Daturine is toxic in large doses whereas Hyoscine which is known as Scopolamine is harmful even in the minutest of the dose. Both are narcotics and classified as illegal drugs.
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