Antidiabetic drugs Flashcards
What are the two groups of D.M?
type 1: insulin dependent D.M
type 2: non-insulin dependent D.M
describe Type 1 D.M…
deficiency of insulin.
- autoimmune attack of beta cells of the pancreas -> gradual depletion of beta cell population -> sx’s appear when 80-90% destroyed -> pancreas fails to respond to ingestion of glucose
what is expected in glucose-induced insulin release test for normal subjects, type 1 D.M, and type 2 D.M?
normal subjects: see a huge rise of plasma insulin when infused of glucose.
Type 1 D.M: see no rise of plasma insulin.
Type 2 D.M: see a slow rise of plasma insulin but below normal subjects.
what are the characteristics of type 1 D.M?
- elevated blood glucose and ketone bodies.
- virtually no insulin secretion
- rely on exogenous insulin injxn SC to control hyperglycemia and avoid ketoacidosis
what are the characteristics of type 2 D.M?
- most common
- combination of insulin resistance and dysfunction beta cells.
- insulin levels may be high, esp early in the disease. but peripheral insulin resistance and increased liver production of glucose make insulin levels inadequate to normalize plasma glucose levels.
- insulin production then falls -> no longer compensate for insulin resistance, hyperglycemia develops.
- metabolic alterations are milder than type 1 D.M
- insulin secretion is enough to restrain ketogenesis.
- HYPERGLYCEMIA but NO KETOACIDOSIS
describe insulin…
- small protein
- 2 polypeptide chains connected by disulfide bonds.
describe insulin secretion…
- released from beta cells at a low basal rate and much higher rate in response to a variety of stimuli.
- stimulated by: glucose, amino acids and GI hormones (incretins)
what is the incretin effect?
glucose given orally results in higher insulin levels than glucose given IV. This is b/c incretins, released by the gut, enhance insulin secretion.
what is the mechanism of insulin secretion in beta cells?
Glucose enters via GLUT transporter -> increased glycolysis and citric acid cycle -> elevated ATP -> closes Katp channel -> less K leaves cell -> cell depolarizes -> Ca channel opens -> Ca entry triggers exocytosis and insulin is secreted.
describe insulin receptor…
- two covalently linked heterodimers.
- each contains an alpha subunit and a beta subunit.
- alpha = extracellular and recognition site for insulin.
- beta = spans the membrane and contains a tyrosine kinase.
how is insulin receptor activated?
- insulin binds to alpha subunit, the tyrosine kinase is activated in the beta subunit -> phosphorylation of tyrosine residues on beta subunit and the cytoplasmic proteins.
what are the effects of insulin on its targets?
- glucose entry in muscle and adipose tissue via GLUT4.
- glycogen synthesis in liver and muscle.
- F.A synthesis and storage as TAG in adipose tissue
- glycolysis
- A.A uptake by muscle
- inhibit gluconeogenesis.
what are the sources of insulin?
- isolated insulin from beef or pork pancreas.
2. recombinant DNA technology using strains of E.coli or yeast.
what are the different types of insulin preparations?
- rapid-acting: fast onset and short duration
- short-acting: rapid onset of action
- intermediate-acting.
- long-acting: slow onset of action
what are the rapid-acting insulins?
- insulin Lispro
- insulin Aspart
- insulin Glulisine
- insulin Lispro
- insulin Aspart
- insulin Glulisine
chemistry?
- native insulin monomers are associated as hexamers
- problem: slow the absorption of insulin
Insulin Lispro
chemical differences compared to insulin B-chain?
28th position: Pro replaced by Lys
29th position: Lys replaced by Pro
Insulin Aspart
chemical differences compared to insulin B-chain?
28th position: Pro replaced by Asp
Insulin Glulisine
chemical differences compared to insulin B-chain?
3rd position: Asp replaced by Lys
29th position: Lys replaced by Glu
- insulin Lispro
- insulin Aspart
- insulin Glulisine
PD and PK?
- mimic the prandial release of insulin.
- given along c a longer acting insulin to assure proper glucose control.
- SC, IV
- give 15mins before a meal
Short-acting insulins
PD and PK?
- regular insulin
- soluble crystallin zinc insulin
- given 30mins before a meal
- SC, IV in emergencies.
what is the intermediate-acting insulins?
Neutral protamine Hagedorn (NPH) - aka isophane insulin.
Neutral protamine Hagedorn (NPH) - aka isophane insulin
PD and PK?
- suspension of crystalline zince insulin combined c protamine.
- SC
- used for basal control.
- given along c rapid- or short-acting insulin for mealtime control.
what are the long-acting insulins?
- Insulin Glargine
2. Insulin Detemir
Insulin Glargine
Chemical difference compared to insulin A-chain?
21st position: Asn replaced by Gly
Insulin glargine
Chemical difference compared to insulin B-chain?
extra Arg-Arg at the end.
How does Insulin glargine get into the Blood?
injxn of an acidic sln (pH 4) -> precipitate in SC tissue -> slow dissolution of free glargine hexamers -> dimers -> monomers -> dimers and monomers can enter capillary membrane -> blood.
Insulin Detemir
Chemical difference compared to insulin B-chain?
29th position: Lys with additional N-C=O-R chain.
What is the difference between insulin analogs vs human insulin preparations?
regimens based on rapid- and long-acting insulin analogs improve HbA1c levels and reduce hypoglycemia compared c regimens c regular insulin and NPH insulin.
What are some ways of insulin administrations?
- syringe
- insulin pen
- insulin pump
- IV
- inhaled
when is best to use IV insulin?
- pts c ketoacidosis, during perioperative period, during labor and delivery, and in Intensive Care situations.
- use regular human insulin
Inhaled insulin
PD and PK?
- dry powder formulation or regular human insulin
- for adults c type 1 and 2 D.M
- peak levels reached in 12-15mins and decline to baseline in 3 hrs.
Inhaled Insulin
A.E and contraindications?
- cough, throat pain, hypoglycemia
- pulmonary function should be monitored.
- pts c asthma, COPD, and smokers.
what is the insulin secretion pattern in the pancreas?
secretes boluses of insulin in response to meals.
b/w meals and throughout the night, secretes small amounts to suppress lipolysis and liver glucose output.
what are the two methods to achieve a similar insulin secretion pattern?
- Basal-Bolus insulin regimens
2. insulin pump therapy
Basal-Bolus Insulin regimens
uses?
- long-acting insulin can be given at bedtime or in the morning.
- if pt skips a meal, omit a premeal bolus.
- if eat a larger meal than usual, increase the premeal bolus.
- dose adjustments can be made to accommodate snacks, exercise patterns, and acute illnesses.
Insulin pump therapy
uses?
- mimic normal insulin secretion
- battery-operated pump and a computer that programs the pump to deliver predetermined amounts of insulin.
What are the insulins used in insulin pump?
- glulisine
- lispro
- aspart
what are the A.E of using insulin therapy?
- hypoglycemia (when overdose)
higher risk in regular insulin than rapid-acting.
higher risk in NPH insulin than long-acting. - Allergic rxns (often d/t noninsulin protein contaminants)
- Lipodystrophy at injxn sites
How to manage hypoglycemia from insulin overdose?
mild case: orange juice, glucose or any sugar-containing bev or food.
severe case (unconsciousness or stupor): IV glucose infusion.
glucagon SC or IM if IV not avail.
What are some of the drug interactions that cause hypoglycemia?
- Ethanol
- Beta blockers
- salicylates
How does EtOH cause hypoglycemia w/ insulin therpay?
inhibits gluconeogenesis.
How does beta blockers cause hypoglycemia w/ insulin therpay?
blocking the effects of catecholamines on gluconeogenesis and glycogenolysis.
also mask the sympathetically-mediated sx’s of hypoglycemia (i.e tremor and palpitations).
How does salicyclates cause hypoglycemia w/ insulin therpay?
enhancing pancreatic beta cell sensitivity to glucose and potentiating insulin secretion.
weak insulin like action in the periphery.
What are some of the drug interactions that cause hyperglycemia by acting on peripheral tissues that counter the actions of insulin?
- epi
- glucocorticoids
- atypical antipsychotics
- HIV protease inhibitors.
What are some of the drug interactions that cause hyperglycemia by inhibiting insulin secretion directly?
- phenytoin
- clonidine
- Ca- channel blockers.
What are some of the drug interactions that cause hyperglycemia by inhibiting insulin secretion indirectly?
Diuretics via depletion of K.
What is the management of Diabetes in Hospitalized pts?
d/c oral anti-diabetics and replaced c insulin.
oral agents can be restarted on discharge.