Usage
- Glucagon is prescribed for the treatment of severe hypoglycemia (low blood sugar) in patients with diabetes mellitus. It is also used as a diagnostic aid in radiologic examinations of the gastrointestinal tract when reduced intestinal motility is desired.
- Pharmacological classification: Hyperglycemic agent, diagnostic aid.
- Glucagon increases blood glucose levels by stimulating hepatic glycogenolysis (breakdown of glycogen to glucose) and gluconeogenesis (production of glucose from non-carbohydrate sources). It also relaxes the smooth muscles of the gastrointestinal tract.
Alternate Names
- Glucagon hydrochloride
- Brand Names: GlucaGen, GlucaGen HypoKit, Glucagon Emergency Kit, GVOKE, Baqsimi
How It Works
- Pharmacodynamics: Glucagon’s primary effect is to increase blood glucose levels. It also inhibits gastrointestinal motility.
- Pharmacokinetics: Glucagon is rapidly absorbed following intramuscular, subcutaneous, or intravenous administration. It is metabolized primarily in the liver and kidneys, with a short half-life of 3-6 minutes. Elimination is via hepatic and renal pathways.
- Mode of Action: Glucagon binds to glucagon receptors on liver cells, activating adenylate cyclase, which increases intracellular cyclic AMP (cAMP). cAMP activates protein kinase A, which phosphorylates and activates enzymes involved in glycogenolysis and gluconeogenesis. Glucagon also has extra-hepatic effects on the gastrointestinal tract through cAMP mediated smooth muscle relaxation.
- Receptor Binding/Enzyme Activation: Glucagon binds to specific glucagon receptors in the liver, initiating a cascade that ultimately leads to increased blood glucose. This involves enzyme activation within liver cells.
- Elimination Pathways: Primarily hepatic metabolism with subsequent renal excretion of metabolites.
Dosage
Standard Dosage
Adults:
- Hypoglycemia: 1 mg subcutaneously, intramuscularly, or intravenously. May repeat after 15 minutes if needed.
- Diagnostic Aid (GI procedures): 0.2–0.5 mg intravenously or 1 mg intramuscularly for upper GI; 0.5–0.75 mg intravenously or 1–2 mg intramuscularly for lower GI.
Children:
- Hypoglycemia: Children < 6 years or < 20 kg: 0.5 mg (or 0.02–0.03 mg/kg) subcutaneously, intramuscularly, or intravenously. Children ≥ 6 years or ≥ 20 kg: 1 mg subcutaneously, intramuscularly, or intravenously. May repeat after 15 minutes if needed.
- Diagnostic Aid: Safety and efficacy not established in children.
Special Cases:
- Elderly Patients: Initiate at lower diagnostic doses due to potential age-related changes in drug response.
- Patients with Renal Impairment: No dose adjustment necessary.
- Patients with Hepatic Dysfunction: No dose adjustment necessary.
- Patients with Comorbid Conditions: Use with caution in patients with insulinoma or pheochromocytoma.
Clinical Use Cases
Glucagon can be administered via IV, IM, SC, or nasal routes in various clinical scenarios:
- Emergency Situations (Hypoglycemia): Administer glucagon as the first line of treatment for severe hypoglycemia if intravenous glucose isn’t immediately available.
- Diagnostic Aid (GI Procedures): For radiologic examinations of the stomach, duodenum, small bowel, and colon by decreasing gastrointestinal motility.
Dosage Adjustments
No specific dosage adjustments are necessary based on renal or hepatic function.
Side Effects
Common Side Effects
- Nausea
- Vomiting
- Injection site reactions (swelling, redness)
- Headache
Rare but Serious Side Effects
- Hypersensitivity reactions (rash, hives, anaphylaxis)
- Hypotension
Long-Term Effects
Not established.
Adverse Drug Reactions (ADR)
Anaphylaxis (rare).
Contraindications
- Pheochromocytoma
- Insulinoma
- Hypersensitivity to glucagon
Drug Interactions
- Insulin: Antagonistic effects.
- Indomethacin: May reduce glucagon’s hyperglycemic effect.
- Beta-blockers: Increased risk of transient increases in heart rate and blood pressure.
- Warfarin: Glucagon may enhance anticoagulant effect.
Pregnancy and Breastfeeding
- Pregnancy Safety Category: B
- Fetal risks: No evidence of fetal harm in animal studies. Limited human data suggests no adverse effects on pregnancy or neonatal health. Glucagon does not cross the placenta.
- Breastfeeding: Expected to be minimally excreted into breast milk due to its high molecular weight. Glucagon is degraded in the digestive tract and is not absorbed intact. No adverse effects on breastfed infants anticipated.
Drug Profile Summary
- Mechanism of Action: Increases blood glucose through hepatic glycogenolysis and gluconeogenesis. Relaxes GI smooth muscle.
- Side Effects: Nausea, vomiting, injection site reactions. Rarely, hypersensitivity/anaphylaxis.
- Contraindications: Pheochromocytoma, insulinoma, hypersensitivity.
- Drug Interactions: Insulin, indomethacin, beta-blockers, warfarin.
- Pregnancy & Breastfeeding: Generally safe.
- Dosage: 1 mg (adult) or 0.5 mg (child <6yrs or <20 kg) IM/IV/SC for hypoglycemia. Various doses for GI procedures.
- Monitoring Parameters: Blood glucose levels, heart rate, blood pressure.
Popular Combinations
Not applicable. Glucagon is typically used alone in emergency situations or for diagnostic purposes.
Precautions
- Patients with a history of insulinoma, pheochromocytoma or glucagonoma.
- Patients subjected to prolonged fasting or starvation.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Glucagon?
A: For adults with hypoglycemia: 1 mg IM/IV/SC. Children < 6 years or < 20 kg: 0.5 mg IM/IV/SC. For GI procedures, see section on dosage.
Q2: How quickly does glucagon work?
A: Blood glucose levels typically begin to rise within 10 minutes of administration.
Q3: What are the common side effects of glucagon?
A: Nausea, vomiting, and injection site reactions.
Q4: Can glucagon be given to pregnant or breastfeeding women?
A: Yes, glucagon is considered safe for use in both pregnant and breastfeeding women. It does not cross the placental barrier and is minimally excreted in breast milk.
Q5: What should be done if a patient doesn’t respond to glucagon?
A: If no response within 15 minutes, a second dose of glucagon can be given. If hypoglycemia persists, intravenous glucose should be administered.
Q6: How is glucagon administered for GI procedures?
A: Glucagon can be given intravenously or intramuscularly, depending on the specific procedure. Doses vary depending on the area of the GI tract being examined.
Q7: Are there any contraindications to glucagon?
A: Yes, glucagon is contraindicated in patients with pheochromocytoma, insulinoma, and hypersensitivity to glucagon.
Q8: How should Glucagon be stored?
A: Store at room temperature below 25°C (77°F). Protect from light. Reconstituted glucagon should be used immediately.
Q9: Does glucagon interact with other medications?
A: It can interact with insulin, indomethacin, beta-blockers, and warfarin. A complete list of interacting drugs should be consulted before administration.
