The History of Amlodipine

Amlodipine is one of the most prescribed medicines in the United Kingdom and across the world, taken daily by millions of people to control blood pressure. Its story has a notable British chapter: the molecule was created by chemists at Pfizer's research centre in Sandwich, Kent. Our editors traced how it came about, what landmark trials showed and what it means for physically active people.

Calcium channel blockers before amlodipine

Calcium channel blockers emerged in the 1960s and 1970s, when researchers found that blocking the entry of calcium into smooth muscle cells of blood vessels caused them to relax. Lower vascular tone means lower blood pressure and less work for the heart.

Early drugs in this class included verapamil, diltiazem and nifedipine. Nifedipine, a dihydropyridine, was effective but short-acting: the original formulations needed several doses a day and could cause rapid drops in blood pressure with reflex increases in heart rate.

These limitations created a clear goal for the pharmaceutical industry: a dihydropyridine that acted smoothly over 24 hours, allowing once-daily dosing and avoiding peaks and troughs.

That goal was taken up by a team at Pfizer's laboratories in Sandwich, which were then one of the company's main research sites outside the United States.

Discovery in Sandwich, Kent

The Sandwich chemists systematically modified the dihydropyridine structure, adding side chains that changed how the molecule behaved in the body. Their work, published by Arrowsmith and colleagues in the Journal of Medicinal Chemistry in 1986, described long-acting dihydropyridines carrying basic substituents — the series that produced amlodipine.

The key feature was ionisation at physiological pH, which slowed absorption and gave the drug a very long elimination half-life, commonly cited as around 30–50 hours. The result was gradual onset and steady blood levels on once-daily dosing.

Amlodipine was launched in the UK at the end of the 1980s under the brand name Istin, and later in the United States as Norvasc. It quickly became one of Pfizer's best-selling products.

After patent expiry in the 2000s, generic amlodipine became extremely inexpensive, which helped make it one of the most widely dispensed medicines in NHS primary care.

• 1960s–70s: first calcium channel blockers enter clinical use.
• 1986: Sandwich team publishes the long-acting dihydropyridine series.
• Late 1980s: UK launch as Istin.
• 2000s: landmark outcome trials and arrival of generics.
• 2019: NICE guideline NG136 keeps CCBs as a first-line choice for many patients.

Landmark trials and place in guidelines

Large outcome trials established amlodipine as more than a blood pressure-lowering drug. The ALLHAT trial, published in JAMA in 2002, compared chlorthalidone, amlodipine and lisinopril in more than 30,000 people and found similar rates of the primary coronary outcome across groups.

The Anglo-Scandinavian Cardiac Outcomes Trial (ASCOT-BPLA), led partly by British investigators, compared an amlodipine-based regimen with an atenolol-based one. Published in The Lancet in 2005, it reported fewer strokes, cardiovascular events and deaths with the amlodipine-based approach, influencing guidelines worldwide.

The VALUE and CAMELOT trials added further data on cardiovascular outcomes and on amlodipine's effect in people with coronary disease.

In current NICE guidance on hypertension (NG136), a calcium channel blocker such as amlodipine is the recommended first step for people aged 55 and over and for people of Black African or African-Caribbean family origin without type 2 diabetes. According to its official labelling, the usual starting dose is 5 mg once daily, with a maximum of 10 mg.

Side effects, interactions and athletes

The best-known side effect is ankle swelling (peripheral oedema), which is dose-related and caused by dilation of small arteries rather than fluid retention. Flushing, headache, dizziness and, less commonly, gum overgrowth can also occur.

Interactions are relevant. The MHRA advised in 2012 that simvastatin should not exceed 20 mg a day when taken with amlodipine because of increased risk of muscle side effects. Strong inhibitors of the CYP3A4 enzyme can also raise amlodipine levels.

For athletes, amlodipine is not on the WADA Prohibited List. Active people with hypertension often tolerate it well because, unlike beta-blockers, it does not blunt the heart rate response to exercise. However, it can contribute to light-headedness after intense exercise when blood vessels are already dilated.

Amlodipine is a prescription medicine, and starting, changing or stopping it should always be done with a GP or cardiologist, not based on gym advice.

Editorial conclusions

Amlodipine is a British-born success story in cardiovascular medicine: a molecule designed for steady, once-daily action that went on to prove itself in some of the largest blood pressure trials ever conducted.

Its strengths are a long half-life, good tolerability and solid outcome evidence; its common drawback is ankle swelling, and interactions such as that with simvastatin need attention.

For physically active people with high blood pressure, it is often a practical option, but the choice of drug belongs to the prescriber, based on the full clinical picture.

We also suggest our articles on blood pressure monitoring for strength athletes, on how beta-blockers affect training and on understanding lipid test results.

References

1. Arrowsmith JE, Campbell SF, Cross PE, et al. Long-acting dihydropyridine calcium antagonists. 1. 2-Alkoxymethyl derivatives incorporating basic substituents. J Med Chem. 1986;29(9):1696–1702.
2. ALLHAT Officers and Coordinators. Major outcomes in high-risk hypertensive patients randomized to angiotensin-converting enzyme inhibitor or calcium channel blocker vs diuretic: the ALLHAT. JAMA. 2002;288(23):2981–2997.
3. Dahlöf B, Sever PS, Poulter NR, et al. Prevention of cardiovascular events with an antihypertensive regimen of amlodipine adding perindopril as required versus atenolol adding bendroflumethiazide as required (ASCOT-BPLA). Lancet. 2005;366(9489):895–906.
4. Julius S, Kjeldsen SE, Weber M, et al. Outcomes in hypertensive patients at high cardiovascular risk treated with regimens based on valsartan or amlodipine: the VALUE randomised trial. Lancet. 2004;363(9426):2022–2031.
5. Nissen SE, Tuzcu EM, Libby P, et al. Effect of antihypertensive agents on cardiovascular events in patients with coronary disease and normal blood pressure: the CAMELOT study. JAMA. 2004;292(18):2217–2225.
6. National Institute for Health and Care Excellence. Hypertension in adults: diagnosis and management (NG136). London: NICE; 2019.