Amlodipine: the pathway in the body
This page shows the biochemical pathway of the active substance Amlodipine: 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
Amlodipine is a dihydropyridine. It settles into a niche of the voltage-gated calcium channel of the L-type and lets less calcium flow into the vessel muscle cell. The channel is a door, not a store.
What this is about
The smooth muscle of the vessel wall tightens over a short chain of steps:
- When the cell wall becomes less negatively charged, the voltage-gated calcium channel of the L-type opens.
- Calcium flows in from outside. The amount of free calcium inside the cell rises for a short while.
- Calcium binds to calmodulin. Only this pair switches on myosin light chain kinase.
- The kinase hangs phosphate onto the light chain of myosin; its counterpart, myosin phosphatase, takes it off again. Out of the contest between the two comes the tension.
Amlodipine settles into a niche of the L-type channel and lets less calcium through. The rise inside the cell therefore turns out smaller, and the step across calcium-calmodulin is set off less often. This changes nothing about the body's stock of calcium: the prescribing information states expressly that serum calcium is unaffected by amlodipine. The channel is a door, not a store.
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
- Amlodipine → Slow absorption The substance is absorbed slowly. The label puts the peak in the blood several hours after swallowing and notes that food does not change the amount absorbed. Source 8
- Slow absorption → Charged in the body At the pH that prevails in the body, amlodipine carries a charge. It settles onto the channel only gradually and comes off just as gradually; the action therefore sets in slowly. Source 8
- Charged in the body → Elimination The liver converts the greater part into inactive breakdown products. These leave the body mostly in the urine. Source 8
- Voltage at the cell wall → L-type channel · voltage sensor The voltage-gated calcium channel of the L-type opens. In the smooth muscle of the vessel wall it is the main route by which calcium comes into the cell from outside. Source 2, 8
- L-type channel → Calcium in the cell L-type channel The inflowing calcium makes the amount of free calcium inside the cell rise. It is this rise alone that is read; at rest the cell holds the amount very low. Source 6, 2
- Calcium in the cell → Calcium-calmodulin · calmodulin Calcium binds to calmodulin, a small protein. The loaded calmodulin changes its shape and can now dock onto myosin light chain kinase. Source 6, 5
- Calcium-calmodulin → Phosphate on myosin MLCK · Mg-ATP Only with calcium-calmodulin bound does myosin light chain kinase work. It transfers phosphate from Mg-ATP onto the light chain of myosin; after that, myosin and actin engage with each other. Source 5, 4
- Store inside the cell → Calcium in the cell IP3 receptor The inflowing calcium makes the amount of free calcium inside the cell rise. It is this rise alone that is read; at rest the cell holds the amount very low. Source 6, 2
What depends on the calcium influx
- Calcium — The L-type channel is the route by which calcium flows from outside into the smooth muscle cell of the vessel wall Source 2, 8
What takes part in these steps
- Magnesium — Myosin light chain kinase transfers phosphate from Mg-ATP; without magnesium it does not work Source 5
- Potassium — Potassium channels set the voltage at the cell wall; on it hangs whether the L-type channel opens Source 7
- Sodium — Drive of the NCX exchanger, which carries calcium out of the cell in trade against sodium Source 6
- ATP — Supplies the kinase with phosphate and drives the pumps SERCA and PMCA that fetch calcium out of the cytoplasm Source 6, 5
- Inositol — Building block of PIP2, from which the messenger IP3 is cleaved that opens the store of the cell Source 6
What the prescribing information states
Controlled trials in the United States in which amlodipine was compared directly against placebo. The prescribing information sorts these four reactions by the amount of the substance: steps 1 to 3 are the three amounts studied, from the smallest to the largest. The figures apply to these trials.
How to read the table: each row carries four figures, and only the comparison says something. For fluid retention the gap to placebo grows markedly with the amount of the substance; for dizziness it stays small. There is no column with another medicine here — this prescribing information compares against placebo alone. And for this table it selected only reactions that were more frequent on amlodipine.
| Amlodipine, step 1 (275) | Amlodipine, step 2 (296) | Amlodipine, step 3 (268) | Placebo (520) | |
|---|---|---|---|---|
| Fluid retention | 1.8% | 3.0% | 10.8% | 0.6% |
| Dizziness | 1.1% | 3.4% | 3.4% | 1.5% |
| Flushing of the face | 0.7% | 1.4% | 2.6% | 0.0% |
| Palpitation | 0.7% | 1.4% | 4.5% | 0.6% |
Four further reactions are named without a link to the amount; they come from all placebo-controlled trials together, 1,730 adults on amlodipine against 1,250 on placebo: fatigue 4.5 against 2.8 of 100, nausea 2.9 against 1.9, abdominal pain 1.6 against 0.3, sleepiness 1.4 against 0.6. Reactions reported after approval are not listed here — the prescribing information notes that neither a frequency nor a causal relationship can be derived from them.
Sources
- Catterall WA, Swanson TM. Structure and Pharmacology of Voltage-Gated Sodium and Calcium Channels. Annu Rev Pharmacol Toxicol 2020 · PubMed 31537174
- Zamponi GW, Striessnig J, Koschak A et al. The Physiology, Pathology, and Pharmacology of Voltage-Gated Calcium Channels and Their Future Therapeutic Potential. Pharmacol Rev 2015 · PubMed 26362469
- Zhao Y, Huang G, Wu J et al. Molecular Basis for Ligand Modulation of a Mammalian Voltage-Gated Ca2+ Channel. Cell 2019 · PubMed 31150622
- Somlyo AP, Somlyo AV. Ca2+ sensitivity of smooth muscle and nonmuscle myosin II: modulated by G proteins, kinases, and myosin phosphatase. Physiol Rev 2003 · PubMed 14506307
- Ran Q, Tian H, Lin J et al. Action and therapeutic targets of myosin light chain kinase, an important cardiovascular signaling mechanism. Pharmacol Res 2024 · PubMed 38944220
- Berridge MJ, Bootman MD, Roderick HL. Calcium signalling: dynamics, homeostasis and remodelling. Nat Rev Mol Cell Biol 2003 · PubMed 12838335
- Jackson WF. Potassium Channels in Regulation of Vascular Smooth Muscle Contraction and Growth. Adv Pharmacol 2017 · PubMed 28212804
- US prescribing information (United States): Amlodipine Besylate Tablets, DailyMed, version of 17 Sept 2026, sections 12.1 Mechanism of Action, 12.2 Pharmacodynamics and 12.3 Pharmacokinetics · Prescribing information
- US prescribing information (United States): Amlodipine Besylate Tablets, DailyMed, version of 17 Sept 2026, sections 6.1 Clinical Trials Experience and 6.2 Postmarketing Experience · Prescribing information
Related pathways
- Candesartan — calcium in the cell
As of 2026-09-25. Draft, written by Claude to schema v2; sources checked in PubMed; expert approval pending
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