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AtroPen Dosage

Generic name: atropine 0.25mg in 0.3mL
Dosage form: auto-injector
Drug classes: Anticholinergic chronotropic agents, Anticholinergics / antispasmodics, Antidotes

Medically reviewed by Drugs.com. Last updated on Sep 15, 2022.

Important Administration Information

  • It is recommended that three ATROPEN autoinjectors be available for use in each patient at risk for organophosphorus or carbamate poisoning; one (1) for mild symptoms plus two (2) more for severe symptoms [see Dosage and Administration (2.2)]. Different dose strengths of ATROPEN are available depending on the patient's weight.
  • ATROPEN should be used by persons who have had adequate training in the recognition and treatment of nerve agent or insecticide intoxication, but may be administered by a caregiver or self-administration if a trained provider is not available.
  • Only administer ATROPEN to patients experiencing symptoms of organophosphorus or carbamate poisoning in a situation where exposure is known or suspected. ATROPEN is a single-dose autoinjector intended as an initial treatment of the muscarinic symptoms of insecticide or nerve agent poisonings (generally breathing difficulties due to increased secretions); definitive medical care should be sought immediately.
  • ATROPEN should be administered as soon as symptoms of organophosphorus or carbamate poisoning appear.
  • In severe poisonings, it may also be desirable to concurrently administer an anticonvulsant (preferably a benzodiazepine) if seizure is suspected in the unconscious individual since the classic tonic-clonic jerking may not be apparent due to the effects of the poison.
  • A cholinesterase reactivator such as pralidoxime may serve as an important adjunct to atropine therapy.
  • Close supervision of all treated patients is indicated for at least 48 to 72 hours.
  • Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit [see Dosage Forms and Strengths (3)].

Dosage Information

Different dose strengths of ATROPEN are available depending on the patient's age and weight (see Table 1).

Table 1: Recommended Dose Strength per ATROPEN Injection
Age and Body Weight Strength of each ATROPEN Injection
Adults and pediatric patients weighing over 41 kg (90 pounds)
(generally over 10 years of age)		 ATROPEN 2 mg (green label)
Pediatric patients weighing 18 kg to 41 kg (40 pounds to 90 pounds)
(generally 4 to 10 years of age)		 ATROPEN 1 mg (red label)
Pediatric patients weighing 7 kg to 18 kg (15 pounds to 40 pounds)
(generally 6 months to 4 years of age)		 ATROPEN 0.5 mg (blue label)
Pediatric patients weighing less than 7 kg (15 pounds)
(generally less than 6 months of age)		 ATROPEN 0.25 mg (yellow label)

Dosage for Mild Symptoms

First Dose: If the patient experiences two or more mild symptoms of nerve agent or insecticide exposure listed in Table 2, administer one (1) ATROPEN injection intramuscularly into the mid-lateral (outer) thigh.

Additional Doses: If, at any time after receiving the first ATROPEN injection, the patient has any of the severe symptoms listed in Table 2, administer two (2) additional ATROPEN injections in rapid succession. If possible, a person other than the patient should administer the second and third ATROPEN injections.

Wait 10 to 15 minutes for ATROPEN to take effect. If after 10 to 15 minutes, the patient does not develop any of the severe symptoms listed in Table 2, no additional ATROPEN injections are recommended.

Dosage for Severe Symptoms

If the patient is either unconscious or has any of the severe symptoms listed in Table 2, immediately administer three (3) ATROPEN injections intramuscularly into the patient's mid-lateral thigh in rapid succession.

Table 2: Common Symptoms of Organophosphorus or Carbamate Poisoning

* These symptoms are sometimes observed in healthy infants and young children. In this age group, these symptoms are less reliable than other symptoms listed. Symptoms must be considered collectively when nerve agent or pesticide exposure is known or suspected.

** Infants may become drowsy or unconscious, with muscle floppiness rather than muscle twitching, soon after exposure to nerve agents or insecticides.
Mild Symptoms Severe Symptoms
  • Blurred vision, miosis
  • Excessive, unexplained teary eyes*
  • Excessive, unexplained runny nose*
  • Increased salivation such as sudden unexplained excessive drooling*
  • Chest tightness or difficulty breathing
  • Tremors throughout the body or muscular twitching
  • Nausea and/or vomiting
  • Unexplained wheezing, coughing or increased airway secretions
  • Acute onset of stomach cramps
  • Tachycardia or bradycardia
  • Strange or confused behavior
  • Severe difficulty breathing or copious secretions from lungs/airway
  • Severe muscular twitching and general weakness**
  • Involuntary urination and defecation*
  • Convulsions
  • Unconsciousness

Administration Instructions

Directions for the Use of 2 mg, 1 mg, and 0.5 mg ATROPEN

  1. Snap the grooved end of the plastic sleeve down and over the Yellow Safety Release. Remove the ATROPEN autoinjector from the plastic sleeve. Do not place fingers on the Green Tip.
  2. Firmly grasp the ATROPEN autoinjector with the Green Tip (needle end) pointed down.
  3. With your other hand, pull off the Yellow Safety Release. ATROPEN is now ready to be administered.
  4. Aim and firmly jab the Green Tip straight down (at a 90° angle) against the mid-lateral thigh. The ATROPEN device will activate and deliver the medicine when you do this. ATROPEN can inject through clothing, but make sure pockets at the injection site are empty. Very thin people and small children should also be injected in the mid-lateral thigh, but before giving ATROPEN, bunch up the thigh to provide a thicker area for injection.
  5. Hold the ATROPEN autoinjector firmly in place for at least 10 seconds to allow the injection to finish.
  6. Remove the ATROPEN autoinjector and massage the injection site for several seconds. If the needle is not visible, check to be sure the Yellow Safety Release has been removed, and repeat steps 4 and 5, but press harder.
  7. After use, using a hard surface, bend the needle back against the ATROPEN autoinjector and either pin the used ATROPEN autoinjectors to the patient's clothing or show the used ATROPEN autoinjectors to the first medical person you see. This will allow medical personnel to see the number and dose of ATROPEN autoinjectors administered. Move yourself and the patient away from the contaminated area right away. Try to find medical help.

Directions for the Use of 0.25 mg ATROPEN

  1. Remove the plastic cap from the yellow tube and slide the ATROPEN autoinjector from the tube. Do not place fingers on the Black Tip.
  2. Firmly grasp the ATROPEN autoinjector with the Black Tip (needle end) pointed down.
  3. With your other hand, pull off the Gray Safety Release. ATROPEN is now ready to be administered.
  4. Bunch up the thigh to provide a thicker area for injection. Aim and firmly jab the Black Tip straight down (at a 90° angle) against the mid-lateral thigh. The ATROPEN device will activate and deliver the medicine when you do this.
  5. Hold the ATROPEN autoinjector firmly in place for at least 10 seconds to allow the injection to finish.
  6. Remove the ATROPEN autoinjector and massage the injection site for several seconds. If the needle is not visible, check to be sure the Gray Safety Release has been removed, and repeat steps 4 and 5, but press harder.
  7. After use, using a hard surface, bend the needle back against the ATROPEN autoinjector and either pin the used ATROPEN autoinjectors to the patient's clothing or show the used ATROPEN autoinjectors to the first medical person you see. This will allow medical personnel to see the number and dose of ATROPEN autoinjectors administered. Move yourself and the patient away from the contaminated area right away. Try to find medical help.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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