Suzetrigine, a Non‐Opioid Small‐Molecule Analgesic: Mechanism of Action, Clinical, and Translational Science

ABSTRACT

The discovery and approval of Suzetrigine (VX‐548, Journavx) marks a significant breakthrough in pain management. It is the first non‐opioid analgesic approved since celecoxib in 1998. Suzetrigine selectively blocks voltage‐gated sodium channel Na_v1.8 and acts exclusively on peripheral nociceptors without crossing the blood–brain barrier, providing analgesia while sparing central nervous system side effects such as dependence, addiction, sedation, and respiratory depression. In vitro experiments have demonstrated that Suzetrigine is a state‐dependent inhibitor with nanomolar potency against human Na_v1.8, exhibiting > 31,000‐fold selectivity compared to other subtypes of sodium channels and molecular targets. Suzetrigine is rapidly absorbed following oral administration with peak plasma concentrations (T _max) in approximately 3 h under fasting conditions and an effective half‐life (t _1/2) of 23.6 h. Suzetrigine is primarily eliminated via hepatic metabolism. Recent phase II and III clinical trials have validated Suzetrigine's efficacy in acute postoperative pain settings, demonstrating statistically significant reductions in pain intensity over 48 h following abdominoplasty and bunionectomy. Additionally, Suzetrigine has shown favorable safety and tolerability in broader acute pain indications and is under continued investigation for the treatment of chronic neuropathic conditions such as diabetic peripheral neuropathy. Pharmacokinetic and pharmacodynamic data support Suzetrigine's rapid oral absorption, state‐dependent Na_v1.8 inhibition, and limited off‐target activity as confirmed by both nonclinical and clinical safety studies. Suzetrigine received approval for use in January 2025 in the United States only. Ongoing trials are exploring novel formulations, long‐term safety, and integration into multimodal regimens for surgical and non‐surgical pain.

Clinical and Translational Card for Suzetrigine.

• Mechanism of action: a selective blocker of voltage‐gated sodium channel Na_v1.8.

• Indication (s): Moderate to severe acute pain in adults.

• Dosage and administration: oral loading dose of 100 mg once on an empty stomach (≥ 1 h before or ≥ 2 h after food consumption), followed by a 50 mg oral maintenance dose every 12 h.

• Major Metabolic Pathway: CYP3A.

• Key PK characteristics: AUC of 11.5 μg × h/mL, C _max of 0.62 μg/mL, T _max of 3 h, t _1/2 of 23.6 h, mean apparent volume of distribution of 495 L, excretion [49.9% as feces (9.1% Suzetrigine and rest as metabolites), 44% as urine (primarily metabolites)], clearance of 13.9 L/h.

1. Introduction

Pain is among the most common clinical symptoms leading individuals to seek medical care. Despite the ubiquity of pain across medical settings—from postoperative recovery to traumatic injuries—adequate pain control remains a major clinical challenge. For moderate‐to‐severe pain, opioids remain widely used due to their potent analgesic effects via μ‐opioid receptor activation in the brain and spinal cord. Although effective, the clinical use of opioids is limited by their adverse effects, such as sedation, respiratory depression, tolerance, dependence, and addiction [1].

Suzetrigine (formerly known as VX‐548; approved brand name: Journavx) is an oral, non‐opioid, selective inhibitor of the voltage‐gated sodium channel Na_v1.8 recently approved for managing moderate‐to‐severe acute pain in adults [2]. Na_v1.8 is preferentially expressed on peripheral nociceptive neurons and mediates pain sensation [3, 4, 5]. By restricting its effects on the peripheral nociceptive neurons, Suzetrigine exhibits analgesic effects without central nervous system (CNS) side effects associated with traditional opioid analgesics [1].

Suzetrigine has been evaluated in a series of early and late‐phase clinical trials to demonstrate its efficacy and safety in both post‐surgical and neuropathic pain models. In phase II randomized, double‐blind trials in patients undergoing abdominoplasty and bunionectomy [6], Suzetrigine demonstrated significantly greater pain relief over 48 h when compared to an inactive oral capsule, while also exhibiting a comparable efficacy to that of hydrocodone/acetaminophen (HB/APAP) treatment. Notably, Suzetrigine achieved these effects without causing opioid‐related side effects, such as sedation, constipation, respiratory depression, and overdose. Further studies have evaluated Suzetrigine as a sustained pain relief treatment in broader surgical and non‐surgical acute pain settings as well as a potential form of treatment for neuropathic pain [7, 8]. Pharmacokinetic advancements have investigated tablet formulations of Suzetrigine, demonstrating practical oral dosing in outpatient care settings [9]. This review aims to summarize the regulatory status, mechanism of action, clinical pharmacology profiles, and key clinical studies for Suzetrigine.

2. Drug Regulatory Approval

On January 30, 2025, the U.S. Food and Drug Administration (FDA) approved Suzetrigine 50 mg oral tablets for the treatment of moderate‐to‐severe acute pain in adults [2]. This approval marks the introduction of the first non‐opioid analgesic in a new therapeutic class in over two decades. The FDA granted Suzetrigine Breakthrough Therapy, Fast Track, and Priority Review designations, offering an effective alternative to opioids and mitigating associated risks. The FDA's decision was based on data from two randomized, double‐blind, placebo‐ and active‐controlled clinical trials (NCT04977336, NCT05034952) involving patients undergoing abdominoplasty and bunionectomy [6].

3. Mechanism of Action

Voltage‐gated sodium channels (Na_vs) are essential transmembrane proteins that initiate and propagate action potentials in excitable cells, including neurons [3]. Each Na_v channel is a heteromeric protein complex composed of a central α‐subunit, which is sufficient to form a functional channel, and one or more auxiliary β‐subunits [3]. The α‐subunit is composed of four homologous domains (DI–DIV), each containing six transmembrane segments (S1–S6) (Figure 1). The voltage‐sensing domain resides in segments S1–S4, of which S4 is the critical voltage sensor containing positively charged residues that respond to changes in membrane potential. Upon depolarization, outward movement of the segment triggers a conformational change of S4 that opens the channel pore, formed by the S5 and S6 segments, allowing sodium ions to flow into the neuron and initiate an action potential [4, 5].

FIGURE 1.

Voltage‐gated sodium channels in peripheral sensory neurons mediate action potential initiation and propagation in response to nociceptive stimuli such as a site of nerve damage. The transmembrane topology of the Na_v1.8 α‐subunit shows a voltage‐gated sodium channel composed of four homologous domains (DI‐DIV), each containing six transmembrane segments (S1‐S6). Suzetrigine binds allosterically to the extracellular S3‐S4 loop of voltage‐sensing domain (VSD2) within DII, modulating channel activity.

In the context of pain, Na_v channels play a pivotal role in the transmission of nociceptive signals from peripheral sensory neurons to the CNS. Among the nine known human Na_v subtypes (Na_v1.1–1.9), Na_v1.7, Na_v1.8, and Na_v1.9 are highly expressed in dorsal root ganglia (DRG) and peripheral nociceptors, making them particularly attractive targets for pain modulation [4, 5]. Na_v1.7 has been implicated in congenital pain syndromes, and its prevalent distribution complicates selective targeting and increases the risk of off‐target effects. Similarly, Na_v1.9 contributes to subthreshold excitability and persistent currents; however, its biophysical properties and broad distribution have made it difficult to develop potent and specific modulators [4, 5]. In contrast, Na_v1.8, encoded by the SCN10A gene and exhibiting resistance to tetrodotoxin, plays a critical role in the depolarization phase of action potentials in nociceptive neurons. This functionality of Na_v1.8 is particularly significant during sustained or repetitive firing, as it remains active at voltages that inactivate other Na_v channels, thus facilitating continued excitability [4]. The upregulation of Na_v1.8 in inflammation and neuropathic pain conditions is mainly restricted to peripheral sensory neurons, where it remains active during chronic stimulation [4]. These properties make Na_v1.8 a desirable pharmacologic target for reducing hyperexcitability in peripheral nociceptors while minimizing CNS effects [5, 10]. While other pathways such as TRPV1 and CGRP also contribute to peripheral pain sensitization, their central expression introduces systemic risks, including hyperthermia or cardiovascular adverse effects. Therefore, the inhibition of Na_v1.8 represents a more selective and safer therapeutic strategy for pain management [11].

Early‐phase clinical studies of selective Na_v1.8 inhibitors including VX‐128 and VX‐150 have provided valuable insights that underpin the development of Suzetrigine (VX‐548). In a Phase 1 study of VX‐128 in healthy adults, VX‐128 induced analgesic effects on cold pressor and pressure pain thresholds, but the study was prematurely terminated due to concerns regarding tolerability, specifically the occurrence of dose‐limiting skin rash and angioedema [12]. In a separate Phase 1 randomized, double‐blind, placebo‐controlled, crossover study of VX‐150, a prodrug Na_v1.8 inhibitor, dose‐dependent analgesic effects were observed across multiple evoked pain models in healthy adults [13]. This study also reported a favorable pharmacokinetic profile and mild adverse events, including headache and pruritus, in comparison to the placebo group, with peak analgesia correlating to maximum plasma concentrations of the active moiety [13]. The findings from the studies of VX‐150 and VX‐128 served as critical foundations for the development of Suzetrigine.

Suzetrigine exemplifies this approach as a state‐dependent, highly selective, and potent inhibitor of Na_v1.8. In vitro electrophysiology experiments have shown that Suzetrigine exhibits nanomolar potency against human Na_v1.8 (IC₅₀ = 0.68 ± 0.16 nM) with > 31,000‐fold selectivity against all other sodium channel subtypes and other molecular targets [10, 14]. Unlike traditional sodium channel blockers such as lidocaine or carbamazepine, which act broadly on multiple Na_v isoforms by binding to pore‐forming regions such as S6 segments and often cause CNS or cardiac side effects, Suzetrigine achieves specificity by allosterically binding to the extracellular S3–S4 loop of the second voltage‐sensing domain (VSD2) in the Na_v1.8 α‐subunit (Figure 1). This region contains a KKGS amino acid sequence unique to Na_v1.8, thereby preventing the initiation and propagation of pain signals with minimal off‐target risks. The absence of this motif in other sodium channel isoforms further highlights Suzetrigine's specificity. Notably, Suzetrigine has no known activity on β‐subunits or closely related channels such as Na_v1.7 or Na_v1.9 [14].

Suzetrigine preferentially stabilizes Na_v1.8 in its closed (resting) state, as shown in electrophysiology experiments where hyperpolarized pre‐pulses enhanced its dose‐dependent inhibition of sodium currents [10, 14]. This indicates that Suzetrigine reduces the likelihood of channel opening and subsequent action potential initiation under conditions of repetitive or pathological firing, rather than broadly suppressing normal excitability. Unlike classical pore blockers such as local anesthetics, which exhibit greater efficacy following depolarization, Suzetrigine acts allosterically, modulating channel gating to tonically suppress nociceptor excitability in a state‐dependent manner. This allows selective targeting of pathologically depolarized neurons, reducing the risk of motor or sensory deficits in healthy tissue [10].

4. Pharmacokinetic/Pharmacodynamic (PK/PD) Characteristics

As of May 2025, the pharmacokinetics and pharmacodynamics of Suzetrigine have been evaluated in seven completed phase I clinical trials (NCT06972212, NCT06820307, NCT05851157, NCT05704556, NCT05635110, NCT05560464, NCT05541471) [15, 16, 17, 18, 19, 20, 21]. Additional studies remain ongoing. Suzetrigine is rapidly absorbed following oral administration with peak plasma concentrations (T _max) in approximately 3 h under fasting conditions, a maximum plasma concentration (C _max) of 0.62 μg/mL, and an area under the plasma drug concentration‐time curve (AUC) of 11.5 μg × h/mL. The drug exhibits a high apparent volume of distribution (Vd) of approximately 495 L, indicating extensive tissue distribution. 99% of the drug is protein‐bound, suggesting limited free drug availability in plasma. The administration of the initial 100 mg dose of Suzetrigine with high‐ to low‐fat meals resulted in decreased initial concentrations of Suzetrigine compared to a fasted state, resulting in a delayed T _max of Suzetrigine to 5 h. However, the C _max and AUC remained unaffected. The administration of a second dose did not affect systemic exposures [21, 22]. Suzetrigine is primarily metabolized by CYP3A enzymes, resulting in the formation of M6‐SUZ, an active metabolite that is approximately 3.7 times less potent than its parent compound in inhibiting Na_v1.8. Suzetrigine is eliminated at a rate of 13.9 L/h, with excretion via both fecal (49.9%) and urinary (44.0%) routes. The effective half‐life (t _1/2) of Suzetrigine is approximately 23.6 h [21, 22].

Clinically, the metabolism of Suzetrigine presents risks for drug–drug interactions. Specifically, plasma exposure to Suzetrigine increases when co‐administered with strong CYP3A inhibitors and decreases in the presence of CYP3A inducers, thereby necessitating dose adjustments or contraindications (Table 1). Additionally, hepatic impairment further modifies drug exposure, with AUC increasing by 1.5‐fold and C _max increasing by 1.3‐fold in patients with Child‐Pugh Class B. This highlights the necessity for dose adjustments in patients with Child‐Pugh Class B, while the use of Suzetrigine in patients with Child‐Pugh Class C remains contraindicated [22, 23]. No significant pharmacokinetic differences have been observed based on age, sex, body weight, race, or in patients with mild renal or hepatic impairment.

TABLE 1.

Summary of clinically relevant interactions between suzetrigine and concomitant medications.

Mechanism/class	Co‐administrated drug	Clinical or theoretical findings	Recommended dose adjustments
Strong CYP3A a Inhibitors	Itraconazole	AUC b s of Suzetrigine and M6‐SUZ increased 4.8‐fold and 4.4‐fold respectively. C max c of Suzetrigine increased 1.5‐fold and M6‐SUZ increased by 32%	Avoid co‐administration or reduce dose; monitor for toxicity
Moderate CYP3A Inhibitors	Fluconazole	AUC of Suzetrigine and M6‐SUZ increased 1.5‐fold and 1.2‐fold respectively. C max of Suzetrigine and M6‐SUZ increased 1.4‐fold and 1.1‐fold respectively.	Dose 1: 100 mg orally on an empty stomach (1 h before or 2 h after food). Dose 2, 3, 4: 50 mg oral dose q12h 12 h after initial dose with or without food Dose 5 and subsequent doses: 50 mg oral dose q24h with or without food 12 h after Dose 4
Strong CYP3A Inducers	Rifampin	AUC of Suzetrigine and M6‐SUZ decreased by 93% and 85% respectively while C max of Suzetrigine decreased by 80% and M6‐SUZ increased by 1.3‐fold	Avoid co‐administration; significant efficacy reduction
Moderate CYP3A Inducers	Efavirenz	AUC of Suzetrigine and M6‐SUZ decreased by 63% and 60% respectively while C max of Suzetrigine is predicted to decrease by 29% and M6‐SUZ is predicted to increase by 1.3‐fold	Avoid or increase dose cautiously; monitor for reduced efficacy
Sensitive CYP3A Substrates	Midazolam	AUC of midazolam decreased by 48% and C max by 37%	No adjustment necessary; monitor for decreased midazolam effects
Proton Pump Inhibitors	Omeprazole	No significant interaction	No adjustment necessary
P‐gp Substrate	Digoxin	No significant changes observed	No adjustment necessary
Hormonal contraceptives	Ethinyl estradiol Levonorgestrel	No significant changes observed	No adjustment necessary

Note: All doses are given orally. Dosing information from US label.

^a CYP: Cytochrome P450.

^b AUC: area under curve.

^c C _max: the highest concentration of Suzetrigine in the blood.

Pharmacokinetic data show minimal CNS penetration and negligible effects in cardiac or skeletal muscles, supporting a reduced risk of sedation or respiratory depression [10]. The most common adverse reactions reported included pruritis, muscle spasms, increased blood levels of creatine phosphokinase, and rash. Patients are advised to avoid eating grapefruit while on the medication [22].

5. Key Clinical Trials

Clinical studies evaluating the efficacy and safety of Suzetrigine included Phase II‐ Bunionectomy (NCT04977336), Phase II‐ Abdominoplasty (NCT05034952), Phase III‐ NAVIGATE‐1: Bunionectomy (NCT05553366), Phase III‐ NAVIGATE‐2: Abdominoplasty (NCT05558410), Phase III‐ Single‐Arm: Mixed Acute Pain (NCT05661734), and Phase II‐ Lumbosacral Radiculopathy (NCT06176196) (Table 2).

TABLE 2.

Summary of key clinical trials evaluating suzetrigine for pain management.

Trial name/phase (clinical trial registration)	Population	N	Design	Dose	Primary endpoint	Key findings	Adverse events
							Commonly reported (> 2.0%)	Severity (> 1.0%)
Phase II‐ Bunionectomy (NCT04977336) [6]	Postoperative acute pain	274	Randomized, placebo‐controlled	100 mg LD, then 50 mg q12h a	SPID48 b	37.8‐point greater pain reduction with high dose Suzetrigine vs. placebo	Nausea (9.5%), headache (7.3%), dizziness (2.2%)	Mild (25.9%), Moderate (6.9%)
Phase II‐ Abdominoplasty (NCT05034952) [6]	Postoperative acute pain	303	Randomized, placebo‐controlled	100 mg LD, then 50 mg q12h a	SPID48 b	36.8‐point greater pain reduction with high dose Suzetrigine vs. placebo	Nausea (28.7%), dizziness (12.9%), headache (8.9%), constipation (8.9%), vomiting (5.3%)	Mild (34.7%), moderate (25.7%)
Phase III‐ NAVIGATE‐1: Bunionectomy (NCT05553366) [24]	Postoperative acute pain	1073	Randomized, double‐blind placebo‐controlled	100 mg LD, then 50 mg q12h a	SPID48 b	Significant vs. placebo (p = 0.0002); −20.2‐ point difference to HB/APAP (p < 0.0001)	Nausea (11.2%), headache (8.0%), dizziness (4.6%), constipation (4.3%), vomiting (3.0%)	Mild (27.9%), moderate (7.8%)
Phase III‐ NAVIGATE‐2: Abdominoplasty‐ (NCT05558410) [24]	Postoperative acute pain	1118	Randomized, double‐blind, placebo‐controlled	100 mg LD, then 50 mg q12h a	SPID48 b	Significant vs. placebo; Not significant to HB/APAP, 6.6‐ point difference (p = 0.2781)	Nausea (25.8%), constipation (9.8%), headache (5.5%), dizziness (5.3%), hypotension (3.8%), vomiting (2.8%)	Mild (31.5%), moderate (21.6%), severe (2.1%)
Phase III‐ Single‐Arm: Mixed Acute Pain (NCT05661734) [7]	Surgical and non‐surgical acute pain	256	Open‐label, single arm	100 mg LD, then 50 mg q12h a	Safety and tolerability	83.2% rated pain relief as good/very good/excellent	Headache (7%), constipation (3.5%), nausea (3.1%), fall (2.3%), rash (2.0%)	Mild (27.7%), moderate (8.2%), participants with AEs leading to discontinuation (2.0%)
Phase II‐ Lumbosacral Radiculopathy (NCT06176196) [8]	Chronic neuropathic pain	218	Randomized, placebo‐controlled	Unspecified	Change in NPRS c at Week 12	Suzetrigine: −2.02 points; Placebo: −1.98 points	22.9% in suzetrigine arm vs. 32.4% in placebo	Mild (13.8%) and moderate (9.2%) in the suzetrigine arm vs. Mild (15.7%) and moderate (15.7%) in the placebo arm

Note: All doses are given orally. Dosing information from US label.

^a Initial loading dose of 100 mg once on an empty stomach followed by maintenance dose of 50 mg every 12 h.

^b SPID48: Pain‐intensity difference over a period of 48 h.

^c NPRS: numeric pain rating scale.

6. Summary of Clinical Efficacy and Safety

Suzetrigine demonstrated a significant reduction in acute pain following abdominoplasty or bunionectomy when compared to placebo. Its efficacy is comparable to hydrocodone/acetaminophen (HB/APAP) treatment (Table 2) [6, 24]. Suzetrigine was generally well‐tolerated with the majority of adverse events (AEs) classified as mild to moderate in severity in phases II and III trials (Table 2). It is important to note that three participants experienced serious AEs (SAEs) that were unrelated to treatment [6, 24].

In Phase III‐ Single‐Arm: Mixed Acute Pain trial, Suzetrigine exhibited high levels of patient satisfaction in the adults experiencing a range of surgical and non‐surgical acute pain conditions. Specifically, 83.2% of participants rated their experience as “good,” “very good,” or “excellent” [7]. This positive response was consistent across subgroups, with 82% of surgical patients and 91.2% of non‐surgical patients reporting favorable outcomes. These results reveal the versatility of Suzetrigine in various clinical settings. Furthermore, the majority of AEs were also classified as mild to moderate (Table 2) [7]. Two participants experienced SAEs that were found to be unrelated to Suzetrigine. Five participants discontinued Suzetrigine due to accidental overdose, arrhythmia, nausea, rash, and somnolence. All reported AEs resolved by the end of the study, with the exception of the participant who experienced arrhythmia. Finally, it is important to note that no opioid‐related side effects, such as respiratory depression or sedation, were reported during the trial.

The effect of Suzetrigine on the management of chronic neuropathic pain was evaluated in the Phase II–Lumbosacral Radiculopathy trial [8]. Suzetrigine resulted in a mean reduction of 2.02 points on the numeric pain rating scale (NPRS) from baseline at the 12‐week assessment, compared to a reduction of 1.98 points observed in the placebo group (Table 2). In line with observations from the other clinical trials, Suzetrigine was generally well tolerated, with AEs reported in 22.9% of participants receiving Suzetrigine, in comparison to 32.4% in the placebo group. Most AEs were characterized as mild or moderate, and no SAEs were attributed to the administration of Suzetrigine.

7. Future Prospects

Following its FDA approval in January 2025 for moderate to severe acute pain, Suzetrigine is undergoing extensive clinical evaluation to expand its therapeutic applications. Two phase III studies are underway to investigate Suzetrigine's role in treating painful diabetic peripheral neuropathy (DPN). One study is a randomized, double‐blind trial (NCT06628908) comparing Suzetrigine to pregabalin and placebo in adults aged 18–80 years old with DPN over 12 weeks, evaluating its efficacy, safety, and tolerability [25]. Another ongoing study is an open‐label extension study (NCT06696443) assessing the long‐term safety and effectiveness of Suzetrigine in participants who completed prior DPN studies [26]. Notably, recent trial reports have also demonstrated dose‐dependent effects on lowering creatinine clearance in patients treated with Suzetrigine for painful DPN, highlighting the importance of closely monitoring renal function in patients with renal insufficiency [27]. Suzetrigine is being explored as part of multimodal analgesic regimens in postoperative settings. A phase IV, open‐label, single‐arm study (NCT06887959) evaluating Suzetrigine's effectiveness and safety in managing acute pain following laparoscopic or arthroscopic surgeries [28]. Additionally, Suzetrigine's application in aesthetic or reconstructive surgeries is being assessed as part of a phase IV trial (NCT06887972) as a multimodal pain management strategy to improve patient satisfaction [29].

Suzetrigine represents a novel advancement in the treatment of pain, yet the broader landscape of pain pathophysiology remains incompletely understood, particularly in chronic and neuropathic pain states. The high placebo response observed in some neuropathic pain trials underscores the need for refined human models that better capture disease heterogeneity. Thus, although Na_v1.8 inhibition offers a promising non‐opioid strategy, there remains a critical need for diversified therapeutic targets to address pain in its many forms and improve outcomes for patients who remain refractory to current interventions.

Conflicts of Interest

The authors declare no conflicts of interest.

Rajasingham R. and Qi Y., “Suzetrigine, a Non‐Opioid Small‐Molecule Analgesic: Mechanism of Action, Clinical, and Translational Science,” Clinical and Translational Science 18, no. 11 (2025): e70414, 10.1111/cts.70414.