Pudexacianinium — ASP-5354
Pudexacianinium (ASP-5354) is a novel near-infrared (NIR) fluorescent imaging agent developed specifically to visualize ureters during minimally invasive surgery. Unlike ICG — which is plasma-protein-bound and does not excrete into urine — pudexacianinium is cleared rapidly through glomerular filtration into the urinary collecting system, producing sustained NIR fluorescence of the ureteral lumen for 60+ minutes after a single IV dose. It is the first purpose-built IV NIR agent for ureteral identification and the functional replacement for indigo carmine in the MIS era.[1][2]
Why It Exists
The clinical gap:
- Indigo carmine (visible blue dye, renally excreted) became unreliable after 2014 supply shortages
- ICG is plasma-protein-bound — does not excrete into urine after IV dosing, so it cannot visualize the ureteral lumen from the inside
- Methylene blue is visible (not NIR) and works for retrograde / intravesical applications but is poorly suited for the purely intravascular-to-urine pathway
- Intraureteral retrograde ICG works but requires cystoscopic catheter placement — extra step, time, and disruption of sterile workflow during robotic pelvic surgery
Pudexacianinium combines the IV convenience of indigo carmine with the NIR penetration and tissue-discrimination advantages of ICG on the same imaging hardware.
Pharmacology
| Property | Value |
|---|---|
| Class | NIR cyanine fluorophore with renal excretion |
| Molecular design | Engineered for rapid glomerular filtration and sustained urinary fluorescence |
| Plasma half-life | Short (minutes) — rapid clearance into urine |
| Route | IV only |
| Peak excitation / emission | ~760 / 800 nm range — compatible with existing NIR imaging systems (Firefly, SPY, Rubina) |
| Duration of visible ureteral fluorescence | ≥60 minutes after single dose |
| FDA approval | Approved in the mid-2020s specifically for intraoperative ureteral visualization |
Why it works
- Rapid glomerular filtration — within minutes of IV injection, the agent concentrates in the urinary collecting system
- Sustained fluorescence in urine — unlike ICG, which clears quickly from plasma into bile, pudexacianinium persists in the ureter for an hour+
- Uses existing NIR hardware — no new imaging platform required; any Firefly / SPY / Rubina setup can visualize it
- Ureteral lumen fluoresces directly — not just adventitial vessels (as with IV ICG), giving a much more definitive ureteral map
GU Applications
1. Intraoperative ureteral identification
The defining use case. IV pudexacianinium is given at the start of the dissection phase; the ureters become visible under NIR within minutes and remain visible for ~60+ minutes.
High-yield scenarios:
- Robotic sacrocolpopexy — ureteral identification during peritoneal dissection
- Robotic hysterectomy / endometriosis surgery — ureteral course in deep infiltrating endometriosis
- Radical prostatectomy / pelvic lymphadenectomy — identification at the level of the pelvic sidewall
- Urologic reoperation — fibrotic pelvic anatomy after prior surgery/radiation
- Deep rectal / colorectal surgery — ureteral protection during LAR / APR / taTME
- Urinary diversion / neobladder construction — confirms ureteral course and patency before ureteroenteric anastomosis
2. Ureteral injury detection
Rapid NIR visualization of urine extravasation confirms intraoperative ureteral injury and localizes the level within seconds — faster than dye instillation or on-table IVP.
3. Complementary to ICG
Pudexacianinium can be combined with ICG during the same operation:
- Give ICG first for perfusion / lymphatic / adventitial assessment (rapidly cleared from plasma)
- Give pudexacianinium for prolonged ureteral visualization during the dissection phase
Dosing and Administration
- IV bolus — dose per manufacturer labeling (dose has evolved through FDA approval studies)
- Fluorescence appears within ~5 minutes of injection
- Sustained fluorescence ≥60 minutes in normal renal function
- Renal dose adjustment — reduce or defer in significant CKD (impaired urinary excretion means poor ureteral fluorescence)
- Can be repeated if fluorescence fades during a long case
Advantages
- First purpose-built IV NIR agent for ureter identification — conceptually a step beyond ICG's off-label ureteral use
- Dissection-phase compatible workflow — single IV bolus at skin incision or early dissection, continuous visibility through the most dangerous phase of the case
- No retrograde cystoscopic access required — unlike intraureteral ICG
- Existing NIR hardware compatible — no capital expense beyond what's already deployed
- Excellent signal-to-background — the ureter glows distinctly against surrounding tissue
Limitations
- High cost — substantially more expensive than methylene blue, ICG, or even historical indigo carmine pricing
- Renal impairment reduces efficacy — in CKD, urinary concentration is suboptimal
- Requires NIR imaging platform — not accessible in pure open or non-NIR laparoscopic cases
- Real-world adoption is still ramping as of 2025–2026 — not yet universal on OR formularies
- Direct head-to-head comparison with retrograde ICG and indigo carmine (when available) still limited
Related Agents
| Agent | Key distinction |
|---|---|
| Pudexacianinium | IV → NIR → urinary ureteral fluorescence ≥60 min (purpose-built) |
| ICG (IV) | IV → NIR → adventitial ureteral outline (plasma-bound, not urine) |
| ICG (retrograde) | Cystoscopic → NIR → urinary ureteral fluorescence (requires catheter placement) |
| Indigo carmine | IV → visible → urinary efflux (historical; shortage-limited) |
| Methylene blue | IV / intravesical → visible → urinary efflux, fistula, orifice (MAO inhibitor) |
| Sodium fluorescein | IV / intravesical → visible yellow-green → urinary (alternative to indigo carmine) |
See Also
- Visualization agents overview
- ICG
- Indigo carmine
- Robotics platforms — NIR imaging hardware
References
1. Slooter MD, Janssen A, Bemelman WA, Tanis PJ, Hompes R. Currently available and experimental dyes for intraoperative near-infrared fluorescence imaging of the ureters: a systematic review. Tech Coloproctol. 2019;23(4):305–313. doi:10.1007/s10151-019-01973-4
2. Al-Taher M, van den Bos J, Schols RM, Bouvy ND, Stassen LPS. Fluorescence ureteral visualization in human laparoscopic colorectal surgery using methylene blue. J Laparoendosc Adv Surg Tech A. 2016;26(11):870–875. doi:10.1089/lap.2016.0264