Atherosclerosis and lipoprotein metabolism Flashcards
Atherosclerosis=
the build up of a
waxy plaque on the inside of
blood vessels.
In Greek, athere means gruel, and
skleros means hard
Atherogensis=
formation of
abnormal fatty or lipid masses in
arterial walls
Atherogensis
Main risk factor is
high blood cholesterol
High Blood Cholesterol
* Estimated 28.5 million adults ≥ 20YO have TC
≥ 240mg/dL (High)
New Cholesterol guidelines in 2018
* Focused on identifying…
* Statins are the primary treatment to reduce —
* Very high risk patients may need combination therapy to reach LDL ≤ –mg/dL
high risk and very high risk patients
cholesterol
70
- Chylomicrons
- Highest proportion of triglycerides
- VLDL
- Very Low Density Lipoprotein
- LDL
(2)
- Low Density Lipoprotein
- “Bad Cholesterol”
- HDL
(2)
- High Density Lipoprotein
- “Good Cholesterol”
- Total Cholesterol
mg/dL
- ≤ 200mg/dL
- HDL
mg/dL
- ≥ 60mg/dL
- LDL
mg/dL
- ≤ 100mg/dL
- Triglycerides
mg/dL
- ≤ 150mg/dL
Friedewald Formula
Total Cholesterol=
LDL
“Bad Cholesterol”
+
HDL
“Good Cholesterol”
+
TG/5
Risk Factors for ASCVD
(7)
- Smoking
- Hypertension
- Hyperlipidemia
- Diabetes mellitus
- Age (men ≥45 yo, women
≥55yo) - Obesity
- Physical Inactivity
- Hyperlipidemia
(2)
- increase LDL and TC
- decreaes HDL
Risk Assessment
ASCVD Risk Score
* Risk Factors used include:
(8)
- age, gender, total and HDL cholesterol, smoking status, blood pressure, diabetes,
and race
Risk Assessment
ASCVD Risk Score
* Estimates…
* Used to guide…
10-year risk of MI or stroke
lipid therapy
- Clinical ASCVD
(3)
- Established Coronary Artery Disease (CAD)
- History of stroke or TIA
- Peripheral Artery Disease (PAD)
No need to calculate ASCVD score if patient has
Clinical ASCVD
Atherogenesis
(7)
Endothelial dysfunction
Endothelial injury
LDL deposits into vessel wall
Formation of foam cells
(Macrophages filled with LDL)
Fatty Streak
Inflammation
(Smooth muscle growth)
Fibrous cap
over lipid core
HDL removes
cholesterol
from
vessel
walls
Atherosclerosis
Patient symptoms
(5)
Angina
Acute Coronary Syndrome
Unstable angina
NSTEMI
STEMI
Lipoprotein metabolism
* Exogenous pathway
- Cholesterol and TG absorbed from diet
transported as chylomicrons to muscle
and adipose tissue - Chylomicrons metabolized by
lipoprotein lipase to release TG - Chylomicron remnants (mostly
cholesteryl esters) return to the liver - Cholesterol in liver may be 1) stored,
2) turned into bile, or 3) enter
endogenous pathway
Lipoprotein metabolism
* Endogenous pathway
- Cholesterol and TG made in liver leave as VLDL
- VLDL metabolized by lipoprotein lipase to
release TG- VLDL becomes LDL - LDL provides cholesterol source for cells to
make cell membranes- also atherogenesis - Cell use an LDL-receptor to take up LDL
- Liver releases HDL to collect cholesterol and
return to liver (reverse cholesterol transport) - Cholesteryl ester transfer protein (CETP)
facilitates the transfer of cholesterol to HDL
HMG-CoA reductase inhibitors (Statins)
Mechanism of Action
* Inhibit…
* Rate-limiting step in…
* Also induce an increase in…
HMG-CoA reductase
endogenous cholesterol production
hepatic LDL receptors
HMG-CoA reductase inhibitors (Statins)
Effects on Lipid parameters
Parameter Change
Total Cholesterol:
LDL:
Triglycerides:
HDL:
decrease 13% to 40%
decrease 17% to 55%
decrease 2 to 28%
increase 2 to 10%
Definitions of High- and Moderate-
Intensity Statin Therapy
High
(2)
Daily dose lowers
LDL by ≥ 50%
Definitions of High- and Moderate-
Intensity Statin Therapy
Moderate
(2)
Daily dose lowers
LDL by 30% -<50%
HMG-CoA reductase inhibitors (Statins)
Clinical benefits
Primary Prevention
(4)
- Target age 40-75 YO with LDL 70-189mg/dL
- Use ASCVD risk score to guide therapy
- Coronary Calcium Score helpful
- Diabetes
Use ASCVD risk score to guide therapy
* — risk = moderate intensity
statin
* — high intensity statin
> 7.5% to ≤ 20%
20%
Diabetes
* All patients get at least — intensity statin
moderate
HMG-CoA reductase inhibitors (Statins)
Clinical benefits
Secondary Prevention
(3)
- All patients under 75 YO with
established ASCVD - High intensity statin
- Very-high risk consider combo
therapy if LDL > 70mg/dL
HMG-CoA reductase inhibitors (Statins)
Pleiotropic effects
* Positive:
(5)
- Plaque stabilization
- Reduced inflammation
- Improved endothelial function
- Reduced platelet aggregability
- Increased neovascularization of ischemic tissue
HMG-CoA reductase inhibitors (Statins)
Pleiotropic effects
* Negative/Neutral:
(2)
- Inhibition of germ cell migration during development
(Pregnancy contraindication) - Immune suppression
HMG-CoA
Adverse Drug Reaction
(2)
H Hepatotoxicity
M Myopathy (ranging from mild soreness to Myositis to rhabdoMyolysis
HMG-CoA
Contraindications
(1)
G Girls (during pregnancy) & Growing children
HMG-CoA reductase inhibitors (Statins)
Drug-Drug Interactions
(3)
- Many DDI due to hepatic metabolism (via CYP450 3A4 or PgP)
- Impaired statin absorption → decreased statin efficacy
- Increased risk of myopathy (pharmacodynamics interaction)
- Many DDI due to hepatic metabolism (via CYP450 3A4 or PgP)
(3)
- Impaired statin metabolism→ increased risk of hepatotoxicity or myopathy
- Impaired clearance of competing drug → increased risk of competing drug
ADRs - Pravastatin and Rosuvastatin are not significantly cleared via CYP450 and
have the least amount of DDI of this type
- Impaired statin absorption → decreased statin efficacy
- Example:
Bile acid binding agents
- Increased risk of myopathy (pharmacodynamics interaction)
- Other drugs that also have a risk of
myopathy (ex. Fibrates)
HMG-CoA reductase inhibitors (Statins)
Example: Atorvastatin
* Brand name: Lipitor®
* MOA:
* Use: (2)
* ADRs:(3)
* Pregnancy category:
* Drug-Drug interactions:
(2)
* Dental implications: Myopathy may present as
HMG-CoA reductase inhibitor
Hyperlipidemia, Prevention of ASCVD
Elevated liver enzymes(hepatotoxicity), myopathy,
rhabdomyolysis
X (contraindicated)
- Increased risk of myopathy with erythromycin, ketoconazole,
itraconazole - Increased effects of midazolam when used in combination
weakness with
chewing or brushing teeth
PCSK-9 Inhibitors
Mechanism of Action
* Block the action of…
* PCSK-9 promotes the
degradation of…
* Inhibition of PCSK-9 results in…
proprotein, subtilisin kexin type 9 (PCSK9)
LDL receptors
more active LDL receptors and lower serum LDL
PCSK-9 Inhibitors
Effects on Lipid parameters
Parameter Change
Total Cholesterol:
LDL:
Triglycerides:
HDL:
decrease ~60%
—–
No effect
Most potent
medication for
LDL lowering
PCSK-9 Inhibitors
PCSK-9 inhibitors are given by —
Cash price was $14,500/year in 2018 price was decrease –% to ~$5,800/year
SQ injection
60
Alirocumab
* Brand name: Praluent®
* MOA:
* Use:
* ADRs: (3)
* Drug-Drug interactions:
* Dental implications:
Binds to proprotein subtilisin kexin type 9 (PCSK9).
Preventing PCSK9 from binding LDL receptors, thereby
promoting LDL degretation within the liver
familial hyperlipidemia and high risk CV patients
Injection site reactions, diarrhea, decreasing LDL too
low
None of significance to dentistry
none
ATP-citrate lyase (ACL) inhibitor
* Bempedoic acid (Nexletol®) only
drug in class
* Inhibit…
* Approved by the FDA in
February 2020
* Not addressed in clinical
guidelines
cholesterol synthesis two
-steps ahead of statins (HMG-
CoA reductase inhibitors)
Bempedoic acid
Effects on Lipid parameters
Parameter Change
Total Cholesterol:
LDL:
Triglycerides:
HDL:
decrease 15-20%
—–
—–
Bempedoic acid
Effects on Lipid parameters
Synergistic LDL lowering when combined with
ezetimibe therapy
Bempedoic acid
* Brand name: Nexletol®
* MOA:
* Use:
* ADRs: (3)
* Drug-Drug interactions:
* Dental implications:
Inhibit cholesterol synthesis two-steps ahead of statins
(HMG-CoA reductase inhibitors)
familial hyperlipidemia and established high risk CV
patients
Elevated uric acid, back pain, elevated liver enzymes
None of significance to dentistry
none
Inhibitors of cholesterol absorption
(Ezetimibe and Bile acid binding agents )
Absorption inhibitor
(3)
Ezetimibe (Zetia®)
Also available with simvastatin
Ezetimibe/Simvastatin (Vytorin®)
Inhibitors of cholesterol absorption
(Ezetimibe and Bile acid binding agents )
Bile acid binding agents
(3)
Cholestyramine (Questran®, Prevalite®)
Colesevelam (Welchol®)
Colestipol (Colestid®)
Ezetimibe
Mechanism of Action
* Blocks…
* Blocking transport protein…
* Does not affect absorption
of (3)
cholesterol absorption in the intestine (duodenum)
NPC1L1 in the brush border of the enterocyte
fat-soluble vitamins, triglycerides, or bile acid
Ezetimibe
Effects on Lipid parameters
Parameter Change
Total Cholesterol:
LDL:
Triglycerides:
HDL:
decrease 10-12%
decrease 18-20%
decrease 1-2%
increase 1-2%
Ezetimibe
Effects on Lipid parameters
Synergistic LDL lowering when combined with
statin therapy
Ezetimibe
* Brand name: Zetia®
* MOA:
* Use:
* ADRs:
* Drug-Drug interactions:
* Dental implications:
Blocks absorption of cholesterol in the intestine by
blocking the NPC1L1 transport protein
hyperlipidemia
Rare- maybe back pain or diarrhea
None of significance to dentistry
none
Bile Acid Binding Agents
Mechanism of Action
* Bind to…
* Prevent resorption of…
* Result in…
bile acid in the
intestine
bile acid
increase uptake of LDL by liver
Bile Acid Binding Agents
Effects on Lipid parameters
Parameter Change
Total Cholesterol:
LDL:
Triglycerides:
HDL:
decrease 15-21%
increase 2-16%
increase 3-9%
Bile Acid Binding Agents
Example: Colesevelam
* Brand name: Welchol®
* MOA:
* Use:
* ADRs: (4)
* Drug-Drug interactions: (3)
Binds bile acid preventing resorption
hyperlipidemia
Mainly GI distress- constipation, abdominal pain, nausea,
dyspepsia
None of significance to dentistry
* Many others due to inhibition of absorption of medications
* Take 1 hour before or 2 hours after other medications
Bile Acid Binding Agents
Example: Colesevelam-Dental Implications
(1)
- Consider semisupine chair position for patient
comfort due to GI side effects of medication
Fibrates
Mechanism of Action
(5)
- Complex mechanism of action
- Agonist of PPARα nuclear receptor
- Increase transcription of
lipoprotein lipase - Marked decrease in VLDL and
triglycerides - Also increase LDL uptake and HDL
synthesis
Fibrates
Effects on Lipid parameters
Parameter Change
Total Cholesterol:
LDL:
Triglycerides:
HDL:
decrease 5-20%
decrease 20-50%
increase 10-20%
Fibrates
Example: Fenofibrate
* Brand name: Tricor® and others
* MOA:
* Use:
* ADRs: (5)
* Drug-Drug interactions: (2)
PPARα nuclear receptor agonist increasing lipoprotein lipase levels
hyperlipidemia- specifically hypertriglyceridemia
Myopathy, dyspepsia, blurred vision/eye floaters, elevations in
liver enzymes, GI distress(abdominal pain)
None of significance to dentistry
* Increase r/o ADRs when combined with statin
Fibrates
Example: Fenofibrate-Dental Implications
(3)
- Consider semisupine chair position for patient
comfort due to GI side effects of medication - Avoid dental light in patient’s eyes; offer
dark glasses for patient comfort due to
vision side effects - May cause dry mouth
Nicotinic acid or its derivatives
Mechanism of Action
* Inhibits..
* Lowers..
* Increases..
hepatic VLDL secretion
serum Triglycerides and LDL
serum HDL
Niacin
Effects on Lipid parameters
Parameter Change
Total Cholesterol:
LDL:
Triglycerides:
HDL:
decrease 10-20%
decrease 20-50%
increase 15-35%
Niacin
Effects on Lipid parameters
Dose of lipid lowering effects —mg daily
500mg-2000
Niacin
Adverse Drug Reactions
(5)
- Flushing
- Gastrointestinal distress
- Liver damage/dysfunction ( liver enzymes)
- Impaired glucose tolerance
- Precipitate gout flare
- Flushing
- Reduced by taking aspirin 30 minutes before dose
- Gastrointestinal distress
- Nausea, vomiting, or diarrhea
- Liver damage/dysfunction ( liver enzymes)
- Can occur at any time during therapy
- Impaired glucose tolerance
- Can worsen a patient’s control of diabetes
- Precipitate gout flare
- increase circulating uric acid level
Niacin
* Brand name: Niaspan®
* MOA:
* Use:
* ADRs: (5)
* Drug-Drug interactions: (2)
* Dental implications:
(2)
Inhibits synthesis of VLDL
hyperlipidemia (particularly hypertriglyceridemia)
flushing, GI distress, Liver dysfunction, glucose intolerance, gout flare
None of significance to dentistry
* Increased risk of hepatotoxicity when combined with statin
- Minor- may cause dizziness so be careful when standing up
- May increase risk of bleeding
