Core pharmacology

Class Group

Pancreatic Hormone

Legacy Cicm Level

Level 3

Indications Uses

1. in the treatment of hypoglycaemia and
2. to facilitate radiological investigation of the gastrointestinal tract and has been used in the management of
3. cardiogenic shock
4. renal colic
5. acute diverticulitis, and
6. propranolol overdose.

Chemical Pharmaceutics

polypeptide hormone extracted from the alpha cells of the pancreatic islets of Langerhans

Presentation

- Prefilled syringes 1mg
- Vials 1/10mg lypophilized glucagon HCl with lactose – reconstituted with glycerol and water

Main Action

Elevation of blood sugar concentration, positive inotropism and chronotropism, and relaxation of smooth muscle

Mechanism of action

acts via cell membrane receptors which stimulate adenylate cyclase activity, leading to an increase in the intracellular
concentrations of cAMP. The final effects of the hormone are mediated via
a cascade of protein kinases

Onset Peak Duration

Onset:
IV- within 1 min
IM/SC – 8-10min

Dur: 10-30min

Physiological effects

CVS: marked positive inotropic and somewhat less marked positive chronotropic effects (synergistic with beta-agonist)

GIT: red GI tone and secretions

GU: decreases the ureteric tone and has a small effect in improving the renal blood flow and urine output.

Metabolic/other:
- increases gluconeogenesis, glycogenolysis, lipolysis, proteolysis, and ketogenesis → ↑ blood sugar
- stimulates release of endogenous catecholamines
and may cause hypokalaemia secondary to an increase in the rate of insulin secretion.

Adverse Effects Toxicity

Nausea/vomiting
Hypo/hyperglycaemia
Diarrhoea
allergy

Absorption

Inactive orally

Metabolism

Proteolysis – splanchnic, hepatic, renal

Clearance

8-12 ml/min/kg
Halved in renal failure

Half-life

3-6min

Special Points

- potentiates warfarin effect

Route And Dose

IV, IM, SC - 1-5mg
IV infusion in 5% glucose: 1-20mg/hr