Fibrates: Definition, Side Effects, Pharmacological Action and Mechanism of Action

They are a class of drugs that reduce the levels of triglycerides in the blood by reducing the production of VLDL and accelerating the elimination of them.

Fibrates are also effective in increasing levels of good cholesterol (HDL) in the blood.

Very high levels of triglycerides (usually greater than 1000 mg) can cause pancreatitis(inflammation of the pancreas that can cause severe illness with severe abdominal pain).

They are not effective in reducing LDL cholesterol (bad cholesterol); however, when a high-risk patient also has high levels of triglycerides in the blood and low HDL (good cholesterol) cholesterol, doctors may consider combining a fibrate with a statin.

Such a combination will not only lower LDL cholesterol but also reduce triglycerides in the blood and increase HDL cholesterol levels.

They have also been used alone to prevent heart attacks, especially in patients with elevated levels of triglycerides in the blood and low levels of HDL cholesterol.

What are the side effects?

Side effects of these include nausea, upset stomach and, sometimes, diarrhea. They can also inflame the liver and cause liver irritation.

However, it is mild and reversible, although occasionally it may be severe enough to require suspension of the medication.

Fibrates can cause muscle damage, especially when taken with statin medications.

Gemfibrozil interferes with the breakdown of certain statins (for example, Simvastatin or Lovastatin), which results in higher levels of statins in the blood and, therefore, a greater likelihood of muscle toxicity due to it.

A serious but uncommon side effect of fibrate therapy is called Rhabdomyolysis , in which the destruction of muscle cells occurs, causing muscle pain, weakness and even death.

The risk of this occurring is greater when renal function is impaired or when fibrates are combined with statins.

What are some examples available in the USA? UU.?

Some fibrates available in the USA UU, are:

  • Gemfibrozil y Fenofibrato.

How does this medicine work?

Reducing the production of triglycerides in the liver and increasing the speed at which triglycerides are eliminated from the bloodstream.

It has been shown that this drug reduces triglyceride levels by 35-50% in patients with high lipid levels. In addition, fibrates (and, in particular, the drug Gemfibrozil ) have been shown to increase HDL cholesterol levels by 15-25%.

The effect of this medication on LDL cholesterol levels is not always the same in all patients. In most people, fibrates slightly decrease LDL-C levels.

However, in others, and particularly in those with a type of hypercholesterolemia called “type I hyperlipoproteinemia,” fibrates may slightly elevate LDL-C levels.

Pharmacological Action

Fibrates are generally effective in reducing elevated levels of triglycerides and cholesterol in the plasma. The magnitude of lipid changes depends on the patient’s lipoprotein status, as well as the relative potency of the fibrate used.

The most pronounced effects are the decrease in triglyceride-rich lipoproteins (TRL) and LDL cholesterol levels.

As for HDL cholesterol levels (HDL-C), they generally increase when initial plasma concentrations are low.

Mechanisms of action of fibrates:

Studies conducted in rodents and humans indicate the main mechanisms of fibrates:

  • Stimulation of lipolysis of lipoproteins.
  • Induction of hepatic fatty acid absorption and reduction of hepatic triglyceride production.
  • Greater elimination of LDL particles.
  • Reduction in the exchange of neutral lipids.
  • Increase in HDL production and stimulation of reverse cholesterol transport.

Are fibrates safe?

They are generally safe, and most patients experience only mild side effects.

Who should take fibrates?

Fibrates are particularly suitable for patients who have high levels of triglycerides in the blood, or patients with low levels of HDL cholesterol.

This is common in patients who have type 2 diabetes. Fibrates can also be prescribed to people with high blood lipids who have not responded to other treatments, such as a statin.