drugs affecting the endocrine system: pancreatic hormones and antidiabetic drugs Flashcards
(95 cards)
insulin definition
a small protein molecule secreted by the beta cells of the pancreas
- Essential to the utilization of glucose by all body cells
normal release of insulin
Insulin is normally released from pancreatic beta cells at a constant low basal rate with intermittent bursts in a response to:
o Stress
o Vagal activity
o High blood glucose levels
insulin actions on the liver
Insulin acts on the liver to increase storage of glucose as glycogen
- and resets the liver after food intake by reversing the amount of catabolic activity
insulin action of the muscle cells
- insulin promotes protein synthesis by increasing amino acid transport and by stimulating ribosomal activity
- promotes glycogen synthesis to replace glycogen stores used during muscle activity
insulins action on adipose tissue
insulin reduces the circulation of free fatty acids and promotes the storage of triglycerides in adipose tissue
rapid-acting insulin
insulin lispro (Humalog), insulin aspart (Novolog), and insulin glulisine (Apidra)
* onset of action: 15-30 min
* peak: 30-90 minutes
* should be injected 15 min before a meal
short-acting insulin
- onset of action: 15-30 min
–> generally lasts for about 4 hrs - duration of action: 12-24 hours
- peak concentration: 1-2 hours
- used as bolus insulin to correct hyperglycemia or to affect food eaten at meals
intermediate-acting insulin
NPH or isophane
* After SC injection, proteolytic enzymes degrade the protamine in NPH to permit slower absorption of the insulin
* Onset of action: 1-2 hours
* Duration: 14-24 hours
* Used as basal insulin in both types 1 and 2
long-acting insulin
Insulin glargine (Lantus, Basaglar, and Toujeo)
* Small amounts of insulin are released slowly and continuously -> resulting in a constant concentration over a time profile of more than 24 hours
- Causes reduction in glucose variability
* onset of action:
- lantus: 3-4 hours
- toujeo: 6 hours
* duration of action: 24 hours or longer
insulin detemir (Levemir)
* onset of action: 3-4 hours
* dose-dependent duration of action: from 6-23 hours
ultra-long acting insulin
insulin degludec (Tresiba)
* the only insulin indicated for the treatment of type 1 and 2 DM in patients 1 year of age or older
* half-life: 25 hours
* duration of action: 42 hours
* should be taken at the same time each day to help maintain its reliable steady-state level
inhaled insulin
Afrezza Inhalation Powder: a new nasally inhaled human insulin
* Contains regular insulin
- particles dissolve in the lungs releasing insulin into the circulation more rapidly than any other type of insulin
- onset of action: 12 minutes
- peak: 35-45 min
- duration of action: 1.5-3 hours
- given with meals
daily dose of insulin
0.3 units/kg/day
bedtime glargine = 50% of total dose
split the remaining 50% w/ SAI before meals
s/s DKA
drowsiness
dim vision
Kussmaul respirations
goals of therapy for BG control
Preprandial BG: 80-130
Postprandial BG: less than 180
Bedtime glucose: 100-140
A1Cs: less than 7%
four primary alterations in glucose metabolism in T2DM
- Insufficient production of endogenous insulin and amylin by the beta cells of the pancreas
- Tissue insensitivity to insulin
- Impaired response of the beta cells to BG levels
- Excessive production of glucose by the liver secondary to increased glucagon levels
glucagon-like peptide -1 (GLP-1)
An incretin hormone released by the intestine through the day and increased in response to a meal
- Stimulates insulin secretion by the beta cells
- Suppresses glucagon secretion
- GLP-1 levels are decreased in T2DM
metformin pharmacodynamics
- Increases peripheral glucose uptake and utilization (insulin sensitivity)
- Decreases hepatic glucose production
- Decreases intestinal absorption of glucose
Additionally
- Improves glucose tolerance and lowers both basal and postprandial plasma glucose levels
- Often results in the patient losing weight
- Inhibits platelet aggregation and reduces blood viscosity
- Has a modestly favorable impact on lipids because of its actions of the liver
metformin dosage
Begin therapy with 500 mg twice daily with the morning and evening meal or 850 mg twice daily with the morning and evening meal for adults
The dose is increased in increments of 500 mg at weekly intervals for both adults and children
Max dose:
* In adults: 2,550 mg/day
* In children: 2,000 mg/day
two major contraindications for metformin
- advanced renal disease
- acute or chronic metabolic acidosis
* tissue hypoperfusion or hypoxia d/t severe dehydration
* heart failure
* respiratory failure
* chronic alcoholism with severe liver damage
monitoring for metformin - assess renal function
before initiating therapy
- serum Cr, CrCl, and eGFR
at least annually thereafter
- serum Cr
reassess eGFR 48 hours after an iodinated contrast imaging procedure if therapy was discontinued
monitoring for metformin - response to therapy
- daily to weekly monitoring of fasting and postprandial BG using SMBG
- by monitoring A1C every 3 months, or monitoring fructosamine every 2 months
after a patient is stabilized
- FBG and A1C levels every 6 months
- SMBG on an intermittent schedule is acceptable
sulfonylureas overview
Work by stimulating insulin release from pancreatic beta cells
- Are true oral hypoglycemics
- Useful only for patients with some endogenous insulin secretion
sulfonylureas pharmacodynamics
Cause an increase in endogenous insulin secretion by the beta cells of the pancreas by closing ATP-sensitive K-channels in the beta-cell plasma membrane, initiating a chain of events resulting in insulin release
- Improve the binding between insulin and insulin receptors, or increase the number of receptors
- Have a limited ability to improve insulin utilization by the tissues
- May produce a mild diuresis
first generation sulfonylureas
o Chlorpropamide
o Tolazamide
o Tolbutamide
