Antihyperlipidemic Drugs Flashcards
How does LDL become oxidized?
LDL is modified by malondialdehyde addition, acetylation, or Cu2+ oxidation. Enters cell by “scavenger receptor” (SR-B1). Macrophage internalizes it, inflammation occurs and atheroma is formed
Which drugs cause hyperlipoproteinemia?
Oral contraceptive pill Glucocorticoids β blockers Thiazides Isotretinoin (vit A derivative) ) Protease inhibitors (anti HIV drugs)
Which drugs are HMG-CoA reductase inhibitors?
Simvastatin Rosuvastatin Fluvastatin Pravastatin Lovastatin Atorvastatin
MOA of HMG-CoA reductase inhibitors
Reversibly and competitively bind HMG-CoA reductase leading to:
Decreased liver cholesterol synthesis
Increased LDL receptor expression
Decreased plasma LDL
These drugs also reduce the production of apoB in the liver and increase liver uptake of VLDL through poE by LDL receptor –> decreased VLDL
Side effect of statins: myopathy and rhabdomyolysis
Rare. Anion transporter (OATP1B1) variant is related with severe myopathy induced by statin.
Mechanism is unclear.
It may be related with decreased downstream products in cholesterol synthesis process.
One of these is farnesyl pyrophosphate, which is needed for CoQ which is needed for formation of ATP by the mitochondria, thus statin decreases ATP in muscle.
The other products of cholesterol synthesis are associated with prenylation, which is needed for protein translocation.
What is myopathy?
Myalgia
Stiffness and muscle weakness
What is rhabdomyolysis?
When muscles are damaged, myoglobin is released and excreted in the urine –> cola coloured urine (can also cause acute renal failure)
Which muscle enzymes are elevated in the blood in the diagnosis of rhabdomyolysis?
Creatine phosphokinase-MM (CPK-MM), SGOT (AST), SGPT (ALT), and LDH
How do statins cause liver damage?
Aminotransferase may increase (within 3 fold of normal value is intermittent). Avoid use in chronic alcohol drinkers, patients with liver diseases
How do statins interact with gemfibrozil?
Taking gemfibrozil with statins increases the chance of rhabdomyolysis by interfering with statin clearance
How do p450 inhibitors affect statins?
Statins are metabolized by cytochrome p450 CYP34A or 2C9
p450 inhibitors enhance toxicity of statins
When are statins contraindicated?
Pregnant and lactating women
Children less than 8 years old
Which drugs are bile acid binding resin?
Cholestyramine
Colestipol
Colesvelam
MOA of bile acid binding resin
Bind to bile acids in the gut resulting in:
Decreased enterohepatic recirculation of bile salts
Increased synthesis of new bile acids in the liver by 10 fold, leading to an increased demand for cholesterol synthesis
Net result is decreased liver cholesterol
Up-regulate LDL receptor –> decreasing blood LDL by 20%
Side effects of bile acid binding resin
Increased VLDL and triglycerides
Constipation (increase dietary fiber to treat)
Cholesterol gall stones
Interfere with absorption of other drugs (Other medications such as digoxin, thiazide, warfarin, tetracycline, thyroxine, iron, statin, ezetimibe, folic acid, vit C, can be given 2 hours apart from resin)
Contraindications of bile acid binding resin
Hypertriglyceridemia
MOA of ezetimibe
Inhibits cholesterol absorption in intestinal brush border (NPC1L1 - Niemann Pick C1 like 1 cholesterol absorption receptor) –> leading to up regulation of LDL receptor
Lowers LDL by 15-20% and increases HDL by 4-9%
Disrupts enterohepatic circulation