From Peptides to Aliskiren: The Evolution of Direct Renin Inhibitors in Hypertension Therapy

Hypertension remains a major global health concern, significantly contributing to the burden of cardiovascular, renal, and cerebrovascular diseases. Conventional pharmacological interventions include calcium channel blockers, beta-blockers, diuretics, Angiotensin-Converting Enzyme Inhibitors (ACEIs), and Angiotensin Receptor (AR) antagonists. However, these therapies often present limitations, particularly in patients with comorbid conditions such as diabetes, where end-organ damage persists despite Renin-Angiotensin-Aldosterone System (RAAS) blockade. A promising alternative lies in targeting the RAAS at its origin-renin, the rate-limiting enzyme responsible for converting angiotensinogen to angiotensin I. Direct Renin Inhibitors (DRIs) offer a mechanistically distinct approach by inhibiting renin's catalytic activity, thereby attenuating downstream RAAS activation. The development of DRIs has evolved through successive generations, beginning with peptide-based inhibitors, such as pepstatin, which demonstrated limited bioavailability and metabolic stability. Subsequent peptidomimetic compounds improved pharmacokinetic profiles but retained structural constraints. The advent of non-peptide DRIs, exemplified by aliskiren (Tekturna), marked a significant breakthrough. Developed via structure-based drug design and molecular modelling, aliskiren exhibits high specificity and oral bioavailability, earning FDA approval in 2007. Despite encouraging preclinical efficacy, clinical trials of aliskiren have yielded mixed results, particularly regarding long-term outcomes and safety in combination therapies. These findings underscore the complexity of RAAS modulation and the need for continued investigation into DRI pharmacodynamics, tissue-specific effects, and patient stratification. This review focuses on the historical trajectory and molecular refinement of DRIs, highlighting the interplay between structural innovation and therapeutic potential in the quest for more effective hypertension management.