Drowsiness hyoscine

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. 

The older (first-generation) antihistamines which tend to cause sedation have antimuscarinic side-effects similar to the actions of hyoscine. (Second-generation antihistamines, which generally do not cause drowsiness, do not exert antimuscarinic side-effects and are of no use for motion sickness.)... 

Cinnarizine is a suitable choice. Hyoscine has more pronounced antimuscarinic side-effects and requires 4-hourly dosing. Drowsiness and antimuscarinic side-effects with cinnarizine are not usually a problem it requires 8-hourly dosing and it will not interact with the patient s medication. Evidence of effectiveness of ginger is conflicting and it may be best not to try it for the first time on a very long journey. 

Procedures that reduce ve.siibularA tsual conflict may help. For example, avoid head movements, and if on the deck of a ship one should fixate on (he horizon, hut if enclosed in a cabin it is better to close one s eyes. Hyoscine is one of the most effective agents to reduce lltc incidence of motion sickness. It is a muscarinic receptor antagonist and frequently causes drowsiness, dry mouth and blurred vision. Cinnarizine is an antihistamine. It has an efficacy similar m that of hyoscine hut produces fewer side-effects. It must be taken 2 hours before exposure to provocative stimulation. 

Except for a much shorter duration of action, the effects of scopolamine are, for practical ophthalmic purposes, the same as those of atropine. The toxic effects of hyoscine hydrobromide are similar to those of atropine, but with hyoscine bradycardia instead of tachycardia occurs and central stimulation rarely precedes depression. Drowsiness leading to coma is the main central symptom. Idiosyncratic reactions are more l ely to occur with scopolamine than with atropine, and ordinary doses occasionally induce severe reactions. Contact dermatitis of the eyelids is less common with scopolamine than with atropine. 

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