Atorvastatin

Atorvastatin belongs to the statin family. It competitively inhibits HMG-CoA reductase, the enzyme that converts HMG-CoA into mevalonate. This reaction governs the slowest step in cholesterol production in the liver, the one that sets its pace. By blocking it, atorvastatin reduces the production of cholesterol by liver cells.

Deprived of part of its internal synthesis, the liver responds by increasing the number of LDL receptors on the surface of its cells. These receptors capture more of the LDL circulating in the blood and remove it from circulation, which lowers the level of LDL cholesterol. The molecule works over a long period: its half-life reaches about 14 hours, and that of its active metabolites, which prolong its effect, ranges from 20 to 30 hours. Its bioavailability remains low, on the order of 14 percent, because a strong first-pass hepatic effect retains a large share of it as soon as it reaches the liver, where it does its work.

The doctor prescribes atorvastatin for dyslipidemias, meaning abnormalities of blood fats. It covers familial hypercholesterolemia, in both its heterozygous and homozygous forms, as well as hypertriglyceridemia. It serves both to prevent a first cardiovascular event in people at risk and to avoid a recurrence, in primary, secondary and tertiary prevention.

LDL cholesterol is the one that infiltrates the walls of the arteries and forms atheromatous plaques there. These plaques reduce the caliber of the vessels and become complicated by heart attack or stroke. By lowering LDL in a lasting way, atorvastatin slows this process and reduces the risk of these events. It is this drop in LDL that underpins the entire value of the treatment.

The tablet is taken once a day, with or without food, at roughly the same time. Its long half-life sets it apart from short-acting statins: it works whatever the moment chosen, morning or evening, provided that this moment is kept from one day to the next. The peak concentration in the blood occurs 1 to 2 hours after intake, but the effect on cholesterol is judged over time, not on a single dose.

The benefit depends on regularity: LDL rises again when the treatment is interrupted, without any signal felt by the person. Any change or any stopping is therefore decided with the doctor, never on one’s own initiative. A diet low in fats and cholesterol, combined with the recommended physical activity, accompanies taking the tablet and acts in the same direction.

Musculoskeletal manifestations are among the effects most often reported in placebo-controlled trials. They include arthralgia in 6.9 percent of people, pain in the extremities in 6.0 percent, musculoskeletal pain in 3.8 percent, muscle spasms in 3.6 percent and myalgia in 3.5 percent. For several of these effects, the frequency reported under placebo remains close to that observed under treatment. Other non-muscular effects appear with a comparable frequency: nasopharyngitis 8.3 percent, diarrhea 6.8 percent, urinary tract infection 5.7 percent, dyspepsia 4.7 percent, nausea 4.0 percent and insomnia 3.0 percent.

Serious muscle damage remains rare. Myopathy is defined by a rise in creatine kinase beyond ten times the upper limit of normal, and rhabdomyolysis is its severe form. Statins, including atorvastatin, are also accompanied by a rise in fasting blood glucose and glycated hemoglobin (HbA1c), which reflects a slight increase in the risk of diabetes. These effects point precisely to what biological monitoring seeks to detect.

Food acts on the same parameter as your treatment: LDL cholesterol. Soluble fibers offer the best-established example. The beta-glucans of oats and barley contribute to the maintenance of normal blood LDL cholesterol, an effect recognized by the EFSA, the European Food Safety Authority. These fibers are found in oats, barley, legumes and apples, which come in addition to the tablet without ever replacing it.

The coenzyme Q10 side follows another logic. A meta-analysis of eight controlled trials shows that statins lower the plasma concentration of coenzyme Q10 (mean difference of -0.44 micromol/L), for all types of statins. The clinical significance of this drop remains debated and is not settled. Food provides little Q10, mainly through meats and oily fish, and the body makes most of it itself. A dietary intake supplements this internal source, without a clinical benefit of supplementation being established to date.

Atorvastatin is metabolized mainly by the cytochrome CYP3A4, with the participation of CYP3A5. Its uptake by the liver goes through the OATP1B1 transporter, while P-glycoprotein, an efflux transporter, limits its absorption in the intestine and excretes it toward the bile. These pathways explain its interactions: a drug that inhibits CYP3A4 or these transporters increases exposure to the molecule and the risk of muscular effects. Grapefruit and its juice produce the same effect and increase exposure to atorvastatin, which justifies discussing their consumption with the doctor during treatment. The molecule’s binding to blood proteins exceeds 98 percent, a factor that also weighs on its interactions.

Biological monitoring frames the treatment. A liver panel, with measurement of transaminases, and a lipid panel are done before initiation. The lipid panel is then checked 4 to 12 weeks after the start or after a dose adjustment, then every 6 to 12 months once the person is stabilized. Blood glucose is monitored in people who are diabetic or at risk of becoming so, in keeping with the effect of statins on blood sugar.