Anticholinergics atropine (Fig 1) and glycopyrrolate (Fig 2) both contain nitrogen atoms. Atropine can cross the blood-brain barrier but glycopyrrolate cannot because, unlike atropine, it carries a permanent charge on its nitrogen atom, which makes it much less lipid soluble. Therefore, glycopyrrolate is free of the unwanted central effects of atropine, such as sedation.

	Atropine	Glycopyrrolate
Presentation	Various ampoule sizes available. Usually presented as 600 μg/ml but for cardiac arrests a prepacked syringe is available with 3 mg in 10 mls (300 μg/ml).	Various ampoule sizes available. Usually presented at a concentration of 200 μg/ml.
Dose	For the treatment of bradycardia, may be titrated to effect with doses of 300 μg up to a maximum of 1.2 mg (1 200 μg).	Titrated to effect with doses of 100-200 μg, up to 600 μg.
Mechanism of action	Both agents block the effects of acetylcholine at the heart resulting in a tachycardia. Both cause a dry mouth.