Each prefilled auto-injector provides a dose of the antidote atropine in a self-contained unit, specially designed for self or caregiver administration. Three strengths of AtroPen® (atropine) are available; they are AtroPen® (atropine) 0.5 mg, AtroPen® (atropine) 1 mg, and AtroPen® (atropine) 2 mg. When activated the AtroPen® 0.5 mg dispenses 0.42 mg atropine base (equivalent to 0.5 mg atropine sulfate), the AtroPen® 1 mg dispenses 0.84 mg atropine base (equivalent to 1 mg atropine sulfate), and the AtroPen® 2 mg dispenses 1.67 mg atropine base (equivalent to 2 mg atropine sulfate). Each AtroPen® delivers atropine in 0.7 mL of sterile pyrogen-free solution containing glycerin, phenol, citrate buffer and water for injection. The pH range is 4.0–5.0.

After the AtroPen® (atropine) Auto-injector has been activated, the empty container should be disposed of properly (see DOSAGE AND ADMINISTRATION). It cannot be refilled, nor can the protruding needle be retracted.

Atropine, an anticholinergic agent (muscarinic antagonist), occurs as white crystals, usually needle-like, or as a white, crystalline powder. It is highly soluble in water with a molecular weight of 289.38. Atropine, a naturally occurring belladonna alkaloid, is a racemic mixture of equal parts of d- and l-hyoscyamine, whose activity is due almost entirely to the levo isomer of the drug. Chemically, atropine is designated as 1 H,5 H-Tropan-3 –ol (?±) -tropate. Its empirical formula is C17H23NO3 and its structural formula is:

Atropine Structural Formula Illustration

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