Insulin

Intramuscular
Diabetic ketoacidosis

Intravenous
Diabetic ketoacidosis

Subcutaneous
Diabetes mellitus

Intramuscular:
Dose reduction may be needed.
Intravenous:
Dose reduction may be needed.
Subcutaneous:
Dose adjustments may be needed.

Intramuscular:
Dose reduction may be needed.
Intravenous:
Dose reduction may be needed.
Subcutaneous:
Dose adjustments may be needed.

Hypoglycaemia.

Pregnancy (insulin requirements tend to fall during the 1st trimester, increase during the 2nd and 3rd) and lactation. Regular monitoring of HbA1c and blood glucose concentrations.

Hypoglycaemia, insulin resistance, lipoatrophy, hypokalaemia, blurred vision.

Inhalation/Respiratory: C; Parenteral: B

Symptoms: Hypoglycaemia. Management: In mild hypoglycaemic episodes, treat with oral glucose. In severe hypoglycaemic episodes, where the patient has become unconscious, treat with IM/SC glucagon (0.5-1 mg) or IV glucose. If the patient does not respond to glucagon within 10-15 minutes, IV glucose must be given. Once consciousness is regained, admin oral carbohydrates to prevent a relapse.

Possible absence of hypoglycaemic warning symptoms with β-blockers. Decreased hypoglycaemic effect with corticosteroids, danazol, diazoxide, diuretics, glucagon, isoniazid, phenothiazine derivatives, somatropin, sympathomimetic agents, thyroid hormones, oestrogens, progestins (e.g. in oral contraceptives), protease inhibitors and atypical antipsychotic (e.g. olanzapine and clozapine). Increased hypoglycaemic effect with oral antidiabetic agents, ACE inhibitors, disopyramide, fibrates, fluoxetine, MAOIs, pentoxifylline, propoxyphene, salicylates and sulfonamide antibiotics. Decreased insulin resistance with octreotide and lanreotide. Increased risk of wt gain and peripheral oedema with pioglitazone, rosiglitazone. Decreased effect of sermorelin.

Description: Insulin lowers blood glucose levels. It regulates carbohydrate, protein and fat metabolism by inhibiting hepatic glucose production and lipolysis, and enhancing peripheral glucose disposal. The various insulin formulations are classified according to their durations of action after SC Inj. They are divided into short-, intermediate-, or long-acting insulin. Soluble insulin (also known as 'neutral insulin' or 'regular insulin') is a short-acting preparation. To extend the duration of action of insulin, preparations are formulated as suspensions in 2 methods. The 1st method involves complexing insulin with a protein so that it is slowly released, e.g. protamine zinc insulin (contains an excess of protamine) and isophane insulin (or NPH insulin which contains equal amounts of protamine and insulin). An alternative method is particle size modification e.g. insulin zinc suspensions. While all the formulations can be admin by SC inj, most by IM inj, only soluble insulin can be admin by IV. Compared to SC inj, IM admin usually has a faster onset of action, with a shorter duration of action.
Onset: 0.5-1 hr (short-acting e.g. soluble insulin); 2 hr (intermediate-acting e.g. biphasic insulin, isophane insulin, amorphous insulin zinc suspensions); 2-3 hr (mixed-insulin Zn suspension); 4 hr (long-acting e.g. insulin zinc suspensions, protamine zinc insulins).
Duration: 6-8 hr (short-acting e.g. soluble insulin); 24 hr (intermediate-acting e.g. biphasic insulin, isophane insulin, amorphous insulin zinc suspensions); 30 hr (mixed-insulin Zn suspension); 36 hr (long-acting e.g. insulin zinc suspensions, protamine zinc insulins).
Pharmacokinetics:
Absorption: Inactivated (oral); fairly rapid (SC); rapid (IM); increased by exercise.
Metabolism: Mainly in liver, also in kidneys and muscle tissue.
Excretion: Small amount excreted as unchanged drug in urine.

Insulin Preparations