Simvastatin: the pathway in the body
This page shows the biochemical pathway of the active substance Simvastatin: where it arrives in the body, where it acts and which steps are affected by that. Every statement has a source. The page describes general textbook knowledge and says nothing about any individual person.
In brief
Simvastatin is a statin. In the body it turns into the open acid form, which settles into the binding pocket of HMG-CoA reductase, the enzyme that converts HMG-CoA into mevalonate. The pocket is occupied only while the substance is present.
What this is about
Cholesterol and coenzyme Q10 arise in the same pathway. It is called the mevalonate pathway and branches only late:
- At the start stands acetyl-CoA, from which HMG-CoA is assembled.
- HMG-CoA reductase converts HMG-CoA into mevalonate. This step sets the pace.
- Only beyond farnesyl pyrophosphate do the branches part: one leads to cholesterol, the other to the isoprene tail of coenzyme Q10.
Simvastatin settles into the pocket of HMG-CoA reductase. This enzyme lies above the fork — the inhibition therefore concerns both branches, not just one. Lower Q10 values in the blood are described on statins; part of that follows the LDL particles in which Q10 travels. What is occupied is the binding pocket of the enzyme — the branches behind it run more slowly, they are not switched off.
What this means in an individual case depends on many things and belongs in a conversation with a doctor or health practitioner.
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The pathway step by step
- Simvastatin → Simvastatin acid · water In the body the ring is opened; the β-hydroxy acid arises, called simvastatin acid. This open form resembles the molecular part HMG. Source 1, 7
- Simvastatin acid → In the liver cell The liver picks up most of it already on the first passage from the portal blood. Only a small part reaches the rest of the circulation. Source 7
- In the liver cell → Excretion CYP3A4 In the liver cell the enzyme CYP3A4 converts the substance further. The breakdown products leave the body mostly with bile and stool, a smaller part with the urine. Source 7
- Acetyl-CoA → HMG-CoA HMG-CoA synthase HMG-CoA is the substance at which the pathway is governed. The next enzyme sets how much mevalonate arises. Source 3
- HMG-CoA → Mevalonate HMG-CoA reductase · NADPH HMG-CoA reductase converts HMG-CoA into mevalonate and uses up two NADPH. This step sets the pace of the whole pathway. Source 3, 2
- Mevalonate → Farnesyl-PP several enzymes · ATP From mevalonate come activated isoprene units, which are joined into farnesyl pyrophosphate. Here the pathway splits into several branches. Source 4
- Farnesyl-PP → Cholesterol squalene synthase etc. · NADPH, oxygen One branch runs via squalene to cholesterol, a building block of every cell membrane and the starting material for bile acids and steroid hormones. Source 3
- Cholesterol → LDL receptors SREBP-2 When cholesterol in the liver cell falls, the regulator SREBP-2 releases more LDL receptors. They fetch LDL particles out of the blood into the cell. Source 5, 7
- Farnesyl-PP → Decaprenyl-PP PDSS1, PDSS2 Another branch lengthens the chain to ten isoprene units. It becomes the tail of coenzyme Q10. Source 4
- Decaprenyl-PP → Coenzyme Q10 COQ2 and COQ enzymes · 4-hydroxybenzoate The enzyme COQ2 attaches the chain to a ring made of 4-hydroxybenzoate. Further COQ enzymes rebuild the ring; ubiquinone is complete with that. Source 4
What this active substance affects
- Coenzyme Q10 — Its isoprene tail arises from farnesyl-PP, which lies in the same pathway below HMG-CoA reductase Source 4, 6
- Cholesterol — Arises from the same mevalonate; the pathway splits only further down, at farnesyl-PP Source 3
- LDL cholesterol — LDL particles carry cholesterol and coenzyme Q10 in the blood; the liver cell fetches them in via LDL receptors Source 5, 6
What takes part in these steps
- NADPH — Electron donor of HMG-CoA reductase; the enzyme uses up two NADPH per mevalonate Source 3
- Tyrosine — Supplies the ring 4-hydroxybenzoate, to which the isoprene chain of coenzyme Q10 is attached Source 4
- SAM (from methionine) — Methyl group donor of the COQ enzymes that rebuild the ring of coenzyme Q10 Source 4
What the prescribing information states
One trial in northern Europe with 2,221 adults who received simvastatin and 2,223 who received a placebo, over a median of 5.4 years. Listed are the reactions that occurred in at least 2 of 100 participants and were more common than on placebo. The figures apply to this trial.
How to read the table: this prescribing information lists only reactions that occurred more often on simvastatin than on placebo — reactions of equal or lower frequency are therefore missing. What matters is the distance within the row, and in most rows it is small: for bronchitis and abdominal pain it is less than half a point.
| Simvastatin (2,221) | Placebo (2,223) | |
|---|---|---|
| Bronchitis | 6.6% | 6.3% |
| Abdominal pain | 5.9% | 5.8% |
| Atrial fibrillation | 5.7% | 5.1% |
| Gastritis | 4.9% | 3.9% |
| Eczema | 4.5% | 3.0% |
| Vertigo | 4.5% | 4.2% |
| Diabetes mellitus | 4.2% | 3.6% |
| Insomnia | 4.0% | 3.8% |
| Muscle pain | 3.7% | 3.2% |
| Urinary tract infection | 3.2% | 3.1% |
| Oedema or swelling | 2.7% | 2.3% |
| Headache | 2.5% | 2.1% |
| Sinusitis | 2.3% | 1.8% |
| Constipation | 2.2% | 1.6% |
Across all trials together the prescribing information counts 2,423 adults with a median follow-up of about 18 months; there 1.4 of 100 participants stopped because of a reaction. Reactions reported after approval are not listed here — the prescribing information states that neither a frequency nor a causal relationship can be derived from them.
Sources
- Schachter M. Chemical, pharmacokinetic and pharmacodynamic properties of statins: an update. Fundam Clin Pharmacol 2005 · PubMed 15660968
- Istvan ES, Deisenhofer J. Structural mechanism for statin inhibition of HMG-CoA reductase. Science 2001 · PubMed 11349148
- Sharpe LJ, Brown AJ. Controlling cholesterol synthesis beyond 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR). J Biol Chem 2013 · PubMed 23696639
- Guerra RM, Pagliarini DJ. Coenzyme Q biochemistry and biosynthesis. Trends Biochem Sci 2023 · PubMed 36702698
- Horton JD, Goldstein JL, Brown MS. SREBPs: activators of the complete program of cholesterol and fatty acid synthesis in the liver. J Clin Invest 2002 · PubMed 11994399
- Nawarskas JJ. HMG-CoA reductase inhibitors and coenzyme Q10. Cardiol Rev 2005 · PubMed 15705257
- US prescribing information (United States): Simvastatin Tablets, DailyMed, version of 25 Aug 2026, sections 12.1 Mechanism of Action, 12.2 Pharmacodynamics and 12.3 Pharmacokinetics · Prescribing information
- US prescribing information (United States): Simvastatin Tablets, DailyMed, version of 25 Aug 2026, sections 6.1 Clinical Trials Experience and 6.2 Postmarketing Experience · Prescribing information
As of 2026-09-25. Draft, written by Claude to schema v2; sources checked in PubMed; expert approval pending
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