Terlakiren

Summary

Terlakiren is a synthetic peptidomimetic that was developed as an oral renin inhibitor for hypertension. Early pre‑clinical work showed it could be absorbed when taken by mouth and lower blood pressure in several animal species. The compound was later withdrawn from development and has not been approved for any therapeutic use. Recent computational screens have also highlighted it as a potential inhibitor of the SARS‑CoV‑2 main protease, although no laboratory confirmation exists.

Mechanism of Action

Renin catalyses the first step of the renin‑angiotensin system, cleaving angiotensinogen to angiotensin I. Terlakiren binds to the active site of renin as a peptidomimetic, blocking this cleavage and thereby reducing downstream production of angiotensin II, a potent vasoconstrictor. By dampening the renin‑angiotensin cascade, it lowers systemic vascular resistance and arterial pressure.

What the Research Shows

A 1995 Pfizer study described the discovery of terlakiren, noting that structural modifications gave it high oral bioavailability and antihypertensive activity in rodents, dogs, and primates. A 1998 investigation of nitric‑oxide involvement showed that terlakiren produced a hypotensive response in sodium‑depleted guinea pigs and rats that was not attenuated by nitric‑oxide synthase inhibition, indicating a blood‑pressure‑lowering effect independent of NO pathways. A 2022 in silico drug‑repurposing screen identified terlakiren among the top predicted binders to the SARS‑CoV‑2 main protease, based on docking and molecular‑dynamics calculations, but the compound was not tested experimentally for antiviral activity. No human clinical trials or regulatory approvals have been reported, and the drug has been withdrawn from further development.

Reported Benefits

In animal models, terlakiren demonstrated oral absorption and effective blood‑pressure reduction after single doses, supporting its intended role as a renin‑blocking antihypertensive. Computational modelling suggests it might also bind viral proteases, raising the possibility of antiviral activity pending experimental validation.

Limitations of the Evidence

Evidence is confined to pre‑clinical animal studies and computer simulations; no human efficacy or safety data exist. The drug was withdrawn before reaching the market, and the antiviral prediction lacks laboratory confirmation. Species‑specific responses and the absence of clinical trials limit confidence in translating these findings to patients.

Safety Considerations

No adverse‑event data are reported in the available animal studies, and the withdrawal of terlakiren indicates that safety, efficacy, or commercial considerations were unresolved. Without human trials, potential toxicities, drug‑interaction profiles, and long‑term effects remain unknown, warranting caution in any speculative use.

How It Is Administered

Terlakiren was formulated for oral administration and demonstrated sufficient gastrointestinal absorption in animal experiments. Intravenous dosing was also employed in early pharmacodynamic studies to assess blood‑pressure effects.

Routes of Administration

Goals & Uses

• Antihypertensive effectCardiovascularModerate
• RAAS blockadeMechanistic/pharmacodynamicModerate

Contraindications

• Hypersensitivity to renin inhibitors or peptidomimeticsImmunologicHigh
• PregnancyPopulationHighPotential fetal risk or insufficient safety data
• Bilateral renal artery stenosisVascular/RenalHigh

Adverse Effects

• Gastrointestinal disturbancesGastrointestinalUnknown
• HypotensionCardiovascularUncommonLow blood pressure
• Renal impairmentRenalUncommon

Drug Interactions

• Angiotensin Receptor Blockers (ARBs)Moderate
• ACE inhibitorsModerate
• Potassium-sparing diureticsModerate

Population Constraints

• Pregnant womenReproductiveAbsolute
• Patients with severe renal impairmentOrgan ImpairmentRelative
• Volume-depleted patientsCardiovascularRelative

Regulatory Status

• European UnionUnapprovedNo EMA approval sought or granted.
• United StatesUnapprovedNever submitted for or granted FDA approval. Development discontinued in the mid-1990s.
• United KingdomUnapprovedNo regulatory approval in the UK.

Never approved by any regulatory agency. Development was discontinued by Pfizer in the mid-1990s. Superseded by later small-molecule renin inhibitors such as aliskiren, which achieved regulatory approval.

Evidence & Sources

• Screening of Clinically Approved and Investigation Drugs as Potential Inhibitors of SARS-CoV-2: A Combined in silico and in vitro Study
  Journal ArticleLowDurdagi S, et al.2022-01-01T00:00:00.000000Z
• Role of nitric oxide in responses to renin-angiotensin system inhibition in sodium-depleted guinea pig and rat
  Journal ArticleLowMangiapane ML, Peters BR1998-01-01T00:00:00.000000Z
• Discovery of inhibitors of human renin with high oral bioavailability
  Journal ArticleLowHoover DJ, et al.1995-01-01T00:00:00.000000Z

Frequently Asked Questions