1. Clinical Overview
Glucagon is a polypeptide hormone secreted by the alpha cells of the pancreatic islets of Langerhans. It is a physiological antagonist to insulin and is a critical agent for the emergency treatment of severe hypoglycemia. The 1mg formulation is a lyophilized powder for reconstitution and injection, functioning as a hyperglycemic agent by promoting hepatic glycogenolysis and gluconeogenesis.
| Onset | Duration | Bioavailability |
|---|---|---|
| Intravenous: 5-15 minutes; Intramuscular/Subcutaneous: 10-15 minutes. | Approximately 60-90 minutes. | Not applicable for injectable formulation; systemic bioavailability is considered 100% post-IV/IM/SC administration. |
2. Mechanism of Action
Glucagon binds to specific G-protein coupled glucagon receptors on hepatocytes. This activates adenylate cyclase, increasing intracellular cyclic AMP (cAMP). Elevated cAMP activates protein kinase A (PKA), which in turn phosphorylates and activates key enzymes. The primary effect is the activation of glycogen phosphorylase and inhibition of glycogen synthase, leading to rapid breakdown of hepatic glycogen into glucose (glycogenolysis). It also stimulates gluconeogenesis, lipolysis, and ketogenesis.
3. Indications & Uses
- Treatment of severe hypoglycemia (low blood sugar) in diabetic patients, particularly when intravenous (IV) glucose is not available or feasible.
- Diagnostic aid in radiologic examinations to temporarily inhibit movement of the gastrointestinal tract.
4. Dosage & Administration
Adult Dosage: For Severe Hypoglycemia: 1 mg (1 unit) by subcutaneous (SC), intramuscular (IM), or intravenous (IV) route. May repeat in 15 minutes if no response. For Diagnostic Use: 0.25-2 mg IV or IM as per radiology protocol.
Administration: 1. Use provided diluent (sterile water for injection) to reconstitute the 1 mg vial. 2. Gently swirl until completely dissolved; do not shake vigorously. 3. Use immediately after reconstitution. Discard any unused portion. 4. For SC/IM: Inject into thigh, abdomen, deltoid, or buttock. 5. For IV: May be administered undiluted or diluted and given as a slow bolus. 6. Once patient responds (regains consciousness), administer oral carbohydrates to prevent recurrent hypoglycemia and replenish glycogen.
5. Side Effects
Common side effects may include:
- Nausea (common)
- Vomiting
- Transient increase in heart rate and blood pressure
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Insulin | Antagonizes hypoglycemic effect of insulin. | Major |
| Beta-blockers (e.g., Propranolol) | Glucagon's hyperglycemic and inotropic effects may be blunted. However, glucagon is used to treat beta-blocker overdose. | Moderate |
| Indomethacin | May potentiate the hyperglycemic effect of glucagon. | Moderate |
| Anticoagulants (e.g., Warfarin) | Glucagon may increase anticoagulant effect; monitor INR. | Moderate |
| Epinephrine | Additive hyperglycemic and cardiovascular effects. | Moderate |
7. Patient Counselling
- DO ensure family members/caregivers are trained to recognize severe hypoglycemia (unconsciousness, seizures) and administer glucagon.
- DO call for emergency medical help (108/102) immediately after administering glucagon.
- DO turn the unconscious patient on their side (recovery position) to prevent choking if they vomit.
- DO administer a fast-acting oral carbohydrate (fruit juice, glucose tablets) once the patient is awake and able to swallow.
- DO NOT use if the powder or solution appears discolored or contains particles.
- DO NOT delay seeking professional medical help.
8. Toxicology & Storage
Overdose: Nausea, vomiting, hyperglycemia, hypokalemia, tachycardia, hypertension. Severe overdose could lead to profound nausea/vomiting and significant electrolyte disturbances.
Storage: Store unopened kit at controlled room temperature (15°C to 30°C). Do not freeze. Protect from light. Keep in the original container. After reconstitution, use immediately and discard any unused portion. Do not store reconstituted solution. Check expiration date regularly.