Antidiabetic Drugs Flashcards
what causes insulin secretion
- glucose
- amino acids
- GI hormones called incretins: glucagon like peptide-1 (GLP-1) and gastric inhibitory peptides (GIP)
mechanism of insulin secretion
hyperglycemia –> increase in ATP levels –> closes ATP dependent K+ channels –> depolarization and opening of voltage gated calcium channels –> influx of Ca2+ –> pulsatile insulin exocytosis
what degrades insulin
inuslinase found in liver gets rid of 60% and kidney the other 40% (roles reversed in insulin dependent diabetics getting SC injections)
mechanism once insulin bind to its receptor
- insulin receptor has two covalently linked heterodimers that have an alpha (extracellular and recognition site) and a beta subunit (contains tyrosine kinase)
- insulin binds to recognition site at the alpha subunit on outside of cell
- this activates the tyrosine kinase on the beta subunit
- tyrosine kinase and cytoplasmic proteins become phosphorylated
- first proteins phosphorylated: insulin receptor substrate proteins (IRS)
- IRS interacts with other signaling molecules to activate gene expression, metabolism, and growth
how does insulin increase uptake of glucose in muscle and adipose tissue
upregulating the GLUT-4 transporter –> hence promoting uptake of glucose by muscle and fat
how does insulin affect lipid metabolism
- inhibits hormone sensitive lipase so decreasing circulating fatty acids
- increases synthesis of fatty acids and TAGs and their storage in adipose tissue by providing glycerol-3-phosphate
- increases lipoprotein lipase providing FA for esterification
what are the four types of insulin preparations
- Rapid acting: fast onset and short duration
- Short acting: rapid onset of action
- intermediate acting
- slow acting: slow onset of action
what are the rapid acting insulin preparation (talks about mechanism)
hexamers slow down the absorption of insulin and reduce its post prandial peak as seen in native insulin but those listed below do not form hexamers
Insulin Lispro
Insulin Aspart
Insulin Glulisine
describe how each of the rapid acting insulin preparations was created
Insulin Lispro: proline and lysine at pos 28 and 29 in B chain are reversed so proline on pos 29 and lysine on pos 28; low propensity to form hexamers
Insulin Aspart: substitution of the B28 proline by aspartate
Insulin Glulisine: replace asparagine with lysine at B3 and lysine by glutamate at B29
what are rapid acting insulin given
they mimic the prandial release of insulin and are less likely to cause hypoglycemia
usually given with a longer acting insulin to ensure proper glucose control
what is the short acting insulin and when should it be given
Regular insulin – given 30 minutes before a meal
safe in preggos
what is the intermediate acting insulin
Neutral Protamine Hagedorn Insulin (NPH) aka Isophane Insulin
why is intermediate acting insulin delayed (name it)
NPH insulin aka Isophane Insulin
delayed absorption of insulin because of conjugation of insulin with protamine
what are the long acting insulins
Insulin Glargine
Insuline Detemir
how is insulin glargine produced
- two arginine residues added to the C terminus of the B chain
- an asparagine in A21 is replaced with glycine on the A chain
what happens to insulin glargine in different pH solutions
soluble in acidic solution but precipitates in neutral pH
what does insulin glargine’s acidic pH (4) prevent it from
can’t be mixed with short acting insulin preparations (insulin lispro, aspart, and glulisine) because they are formulated at neutral pH
describe the peak of insulin glargine
it has a peakless absorption profile
describe how was insulin detemir was created
terminal threonine is removed from the B30 position and myristate is attached to the new terminal B29 lysine
what has a lower risk of hypoglycemia in comparison to NPH insulin
Insulin Glargine
Insulin Detemir
benefits of rapid acting insulin over regular human insulin
- rapid acting can be taken right before a meal
- improved post prandial glycemic control and less risk of hypoglycemia
overall benefit of using rapid and long acting insulin over NPH and regular human insulin
- improvements in HbA1C levels
- better glycemic control
- reduced hypoglycemia
what type of insulin is used when IV therapy is warranted
regular human insulin
AE of inhaled insulin
cough
throat pain or irritation
hypoglycemia
contraindications of inhaled insulin
asthma
COPD
smokers
goal of SC insulin therapy
replace the normal basal (overnight, fasting, and between meals) as well as bolus or prandial (meal time) insulin
two methods used to simulate normal insulin release pattern
- basal bolus insulin regimen: once to twice a day dose of basal insulin coupled with premeal doses of rapid or short acting insulin
- insulin pump therapy: delivers various basal amounts of insulin over 24 hours as well as meal related boluses
AE of basal bolus insulin regimen and insulin pump therapy
- hypoglycemia
- allergic reactions
- lipodystrophy at injection site
drugs that commonly causes hypoglycemia
BES
beta blocker
ethanol
salicylates
how does ethanol cause hypoglycemia
inhibits gluconeogenesis
how do beta blockers cause hypoglycemia
- block the effects of catecholamines on gluconeogenesis (beta 2 causes increase in glycogenolysis and gluconeogenesis)
- also blocks the symptoms of hypoglycemia by blocking tremors and tachycardia
how does salicylates cause hypoglycemia
- weak insulin like activity in periphery
- enhance pancreatic beta cells sensitivity to glucose and potentiating insulin secretion
Drugs that cause hyperglycemia by countering the actions of insulin
HAGE
HIV protease inhibitors
Atypical antipsychotics
Glucocorticoids
Epinephrine
drugs that cause hyperglycemia by inhibiting insulin secretion directly and indirectly
Directly:
Phenytoin
Clonidine
Calcium channel blockers
Indirectly:
diurectics by depleting K+
non insulin antidiabetic agents
BIT BAGID
- Biguanides
- Insulin Secretagogues: Sulfonylurea and Meglitinides
- Thiazolidinediones (TZDs)
- Bile acid sequestrants
- Amylin Analogs
- alpha-Glucosidase inhibitors
- Incretin analogs
- DPP-IV inhibitors
what are the “oral hypoglycemics”
- Biguanides
- Insulin Secretagogues: Sulfonylurea and Meglitinides
- Thiazolidinediones (TZDs)
-alpha-Glucosidase inhibitors
what are the insulin secretagogues
sulfonylurea and meglitinides
what are the sufonylureas
Chlorpropamide
Glyburide
Glipizide
Glimepiride