Trimetazidine

Trimetazidine (1-(2,3,4-trimethoxybenzyl)piperazine) is a metabolic anti-ischemic agent developed by Laboratoires Servier in the late 1960s and first marketed in France in 1978 under the trade name Vastarel. It is registered in approximately 100 countries for the treatment of stable angina pectoris as add-on therapy to hemodynamic antianginal agents and, in certain jurisdictions, for symptomatic management of vertigo, tinnitus, and visual disturbance of vascular origin, although the European Medicines Agency restricted the latter indications following a 2012 Article 31 referral. The compound is not approved by the United States Food and Drug Administration and is not available in the United States, Canada, or the United Kingdom.

The molecular mechanism of trimetazidine is metabolic rather than hemodynamic. The compound selectively inhibits the mitochondrial long-chain 3-ketoacyl coenzyme A thiolase (3-KAT, also designated mitochondrial trifunctional protein thiolase), the terminal enzyme in the beta-oxidation spiral of long-chain fatty acids, with an IC50 of approximately 75 nanomolar as originally reported by Kantor et al. (2000) in isolated working rat hearts, although subsequent work by MacInnes et al. (2003) using purified enzyme preparations challenged the direct enzymatic inhibition and proposed alternative upstream targets. The functional consequence of 3-KAT inhibition is a shift in myocardial energy substrate preference from fatty acid oxidation (which consumes more oxygen per mole of ATP generated) to glucose oxidation (which is approximately 12 percent more oxygen-efficient per unit of ATP), thereby preserving myocardial high-energy phosphate pools under ischemic conditions without altering heart rate, blood pressure, coronary blood flow, or rate-pressure product. The compound additionally increases pyruvate dehydrogenase activity, reduces intracellular calcium overload, attenuates reactive oxygen species generation, decreases neutrophil infiltration in ischemic myocardium, and preserves intracellular pH homeostasis during ischemia and reperfusion.

The clinical evidence base for trimetazidine in stable angina pectoris is extensive. Multiple randomized controlled trials, including the TRIMPOL-I, TRIMPOL-II, and VASCO-angina studies, have demonstrated that trimetazidine as add-on therapy to beta-blockers, calcium channel blockers, or long-acting nitrates produces statistically significant improvements in total exercise duration, time to 1 mm ST-segment depression, and weekly angina attack frequency compared to placebo. The 2024 European Society of Cardiology guidelines for chronic coronary syndromes assign trimetazidine a Class IIb, Level of Evidence B recommendation as add-on antianginal therapy in patients with inadequate symptom control, a downgrade from the prior Class IIa designation that has been criticized by some experts as inconsistent with the available trial evidence. A separate and growing literature supports benefit in heart failure with reduced ejection fraction (HFrEF): multiple meta-analyses (Gao et al. 2011, Zhang et al. 2012, Weng et al. 2024) pooling data from over 1,500 patients have reported mean improvements in left ventricular ejection fraction of 6 to 7.5 percentage points, reductions in cardiac hospitalization (relative risk 0.43), and reductions in all-cause mortality (relative risk 0.47), leading to inclusion of trimetazidine in the 2021 ESC heart failure guidelines at a Class IIb level for relief of persistent angina in heart failure patients.

Pharmacokinetics are characterized by rapid and near-complete gastrointestinal absorption, approximately 90 percent oral bioavailability, a plasma elimination half-life of approximately 6 hours for the immediate-release formulation (approximately 12 hours for the modified-release 35 mg formulation), renal elimination of approximately 60 percent of the administered dose as unchanged drug, and minimal hepatic cytochrome P450-mediated metabolism with low drug-drug interaction potential. The compound is generally well tolerated; the principal adverse events are gastrointestinal disturbance (nausea, epigastric discomfort), asthenia, headache, and dizziness. The most clinically significant safety signal is the induction of reversible parkinsonian symptoms (rest tremor, bradykinesia, gait disturbance, rigidity) in a small fraction of patients, predominantly elderly, on prolonged therapy. This signal prompted the 2012 EMA Article 31 referral that resulted in new contraindications (Parkinson disease, parkinsonian symptoms, tremor, restless leg syndrome, severe renal impairment) and restriction of indications. Symptoms resolve in most patients within weeks to months of drug discontinuation. This monograph reviews the chemistry, synthesis, and structural pharmacology of trimetazidine; the metabolic mechanism of action in molecular detail; the comprehensive pharmacokinetic profile; the clinical evidence base across angina, heart failure, and investigational indications; sourcing and quality considerations; reconstitution and handling; stack-interaction implications; the adverse-event and safety signal record; and a structured comparative assessment of five alternative metabolic and antianginal agents against trimetazidine on five competency standards.