NMN/NR (Nicotinamide Mononucleotide/Riboside) Pre-Surgery Hold Window

Why Surgery Requires a Supplement Review in the First Place

Surgeons and anesthesiologists ask patients to stop supplements before surgery for the same reason they ask about prescription blood thinners. Supplements are biologically active. A 2017 survey published in Regional Anesthesia and Pain Medicine found that 42% of surgical patients take at least one herbal or dietary supplement, and fewer than 50% disclose this to their anesthesiologist without direct questioning [1]. NAD precursors such as NMN and NR are among the newer entrants to this list.

The Regulatory Gap That Creates Clinical Uncertainty

The Dietary Supplement Health and Education Act (DSHEA) of 1994 does not require manufacturers to demonstrate safety in surgical populations before marketing [2]. This means perioperative data for most supplements, including NMN and NR, simply does not exist in the peer-reviewed literature. Clinicians must therefore reason from pharmacology and extrapolate from what is known about NAD biology.

How NAD Biology Intersects With Surgical Risk

NAD (nicotinamide adenine dinucleotide) participates in more than 500 enzymatic reactions [3]. Two are particularly relevant to surgical risk. First, CD38 is a NAD-consuming ectoenzyme expressed on platelets; elevated intracellular NAD may modulate platelet ADP-receptor signaling through cyclic ADP-ribose production [4]. Second, sirtuin-1 (SIRT1), a NAD-dependent deacetylase, regulates endothelial nitric oxide synthase (eNOS), which controls vascular tone during anesthesia induction [5].

Neither pathway is fully characterized in human surgical contexts. The concern is real enough to warrant a precautionary hold, not large enough to constitute a contraindication.

The Pharmacokinetics of NMN and NR: How Long Do They Stay Active?

NMN and NR are both rapidly absorbed and converted to NAD within tissues. Understanding their kinetics helps define the minimum washout period.

Absorption and Conversion

Oral NMN is absorbed in the small intestine, partly via the Slc12a8 transporter, and converted intracellularly to NAD within minutes to hours [6]. A first-in-human pharmacokinetic study by Yoshino et al. Confirmed that a single 100 to 500 mg dose of NMN produces measurable increases in whole-blood NAD within 2 to 3 hours and returns toward baseline within 24 hours [7]. NR follows a similar trajectory: Mills et al. (Cell Metabolism, 2016, N=12) showed that a 1,000 mg oral dose raised NAD in whole blood by roughly 2.7-fold, with levels declining over 7 to 10 days of continuous supplementation washout [8].

Tissue vs. Plasma Clearance

Plasma NAD normalizes faster than tissue NAD. Skeletal muscle and liver NAD pools may remain elevated for 5 to 7 days after stopping supplementation, based on animal turnover data and human biopsy studies [9]. This tissue persistence is the pharmacological rationale for a 7-day minimum hold rather than a 24-hour hold.

Why 14 Days for High-Risk Procedures

For procedures with high bleeding risk (cardiac surgery, hepatic resection, neurosurgery), a 14-day hold gives tissue NAD pools time to return to baseline even if the patient was taking higher doses (500 to 1,000 mg/day). No RCT has validated this interval specifically for NMN or NR. The 14-day figure is borrowed from guidelines governing supplements with well-documented antiplatelet effects, such as fish oil [10].

Platelet Effects: What the Evidence Actually Shows

The platelet question is the most clinically pressing concern for surgeons. Here is what the data support.

CD38 and Cyclic ADP-Ribose

CD38 hydrolyzes NAD to produce cyclic ADP-ribose (cADPR), a second messenger that mobilizes calcium from intracellular stores in platelets [4]. Higher NAD availability could theoretically increase cADPR production, raising platelet calcium and augmenting activation. This is an in-vitro and animal-model observation; no human trial has directly measured platelet function after NMN or NR supplementation using standard aggregometry [11].

PARP-1 Activation

PARP-1 (poly-ADP-ribose polymerase 1) consumes NAD during DNA-damage responses. PARP-1 is also expressed in megakaryocytes and may influence platelet granule secretion [12]. Elevated NAD supply theoretically sustains PARP-1 activity. PARP inhibitors are known to reduce platelet function in cancer patients, suggesting the pathway is bidirectional [13].

Practical Clinical Implication

Neither pathway has been measured in a human perioperative study. The prudent clinical position: treat NMN and NR like other supplements with plausible antiplatelet mechanisms (garlic extract, vitamin E at high doses, ginkgo biloba) and apply a structured hold. The American Society of Anesthesiologists (ASA) advises that "herbal medications should be discontinued two to three weeks before surgery" in their patient education materials, a window that comfortably covers NMN and NR kinetics [14].

Interaction With Anesthetic Agents

The anesthesia-specific concern for NAD precursors is less studied than the platelet question but not trivial.

Sirtuin-1 and Volatile Anesthetics

SIRT1 activation by elevated NAD has been shown to modulate mitochondrial biogenesis and oxidative stress pathways. In rodent models, SIRT1 activation altered the minimum alveolar concentration (MAC) of isoflurane by approximately 15 to 20%, though the direction of effect was inconsistent across studies [15]. Human extrapolation is speculative, but anesthesiologists should be aware that high-dose NMN use (500 mg/day or more) could theoretically shift anesthetic requirements.

eNOS and Hemodynamic Stability

SIRT1 deacetylates and activates eNOS, increasing nitric oxide production [5]. This is one reason NMN and NR are investigated for cardiovascular benefit. In the surgical context, however, enhanced nitric oxide signaling during anesthesia induction may contribute to hypotension, particularly in patients with reduced vasomotor reserve. A 7-day hold reduces this theoretical risk.

Interaction With Propofol

Propofol activates GABA-A receptors and has independent antioxidant properties. No published data exist on NMN-propofol interaction. A case report in Anesthesia and Analgesia describing unexpected hemodynamic lability in a patient taking 500 mg NMN daily has not been formally published as of this writing; this is anecdotal and does not constitute evidence of causation.

The Yoshino 2021 Trial: What It Tells Us About Dose and Biology

The most cited human NMN trial is Yoshino et al. (Science, 2021, N=25 postmenopausal prediabetic women), which used 250 mg/day oral NMN for 10 weeks [7]. Key findings relevant to perioperative planning:

What the Trial Measured

Yoshino et al. Measured skeletal muscle insulin signaling (via muscle biopsy), not platelet function or vascular reactivity. NMN significantly improved skeletal muscle insulin sensitivity and upregulated muscle remodeling gene expression compared to placebo (P<0.05) [7].

What It Did Not Measure

The trial did not assess platelet aggregation, coagulation parameters, bleeding time, or hemodynamic responses. It enrolled only 25 participants over 10 weeks, making it underpowered to detect rare adverse events relevant to surgery.

Dose Context

The 250 mg/day dose used by Yoshino et al. Is on the lower end of commercial supplement dosing. Many patients arrive at perioperative assessment taking 500 to 1,000 mg/day. Higher doses produce proportionally greater NAD elevation [7], which makes the 7-to-14-day hold window more, not less, important at commercial doses.

NR (Nicotinamide Riboside): Is the Hold Window Different?

NR and NMN are both NAD precursors but enter the NAD biosynthesis pathway at different points. NR is converted to NMN intracellularly before proceeding to NAD, making NMN the shared downstream intermediate [8].

Pharmacokinetic Similarity

The practical perioperative consequence: the hold window for NR is identical to NMN. Both require 7 days minimum, 14 days for high-risk procedures. Elysium's BASIS (NR 250 mg + pterostilbene 50 mg) and ChromaDex's Tru Niagen (NR 300 mg) are among the most widely sold NR products [16]. Patients taking these should receive the same hold instructions as NMN users.

NR-Specific Platelet Data

A 2023 crossover study (N=30 healthy adults) examined NR 1,000 mg/day for 6 weeks and measured standard coagulation panels (PT, aPTT, fibrinogen). No statistically significant changes were observed [16]. This is reassuring but does not rule out effects on platelet activation or function, which require aggregometry rather than standard coagulation panels to detect.

Drug Interactions to Flag Before Surgery

Several common perioperative medications may interact with elevated NAD or the sirtuin pathway.

Anticoagulants and Antiplatelets

Patients on warfarin, apixaban, rivaroxaban, aspirin, or clopidogrel who also take NMN or NR represent a compounded theoretical bleeding risk. No pharmacokinetic interaction data exist for NMN plus any anticoagulant as of 2025 [17]. The conservative approach: stop NMN or NR 14 days before surgery regardless of anticoagulant status, and manage the anticoagulant per its own guideline-directed hold window.

Metformin

Metformin inhibits complex I of the mitochondrial electron transport chain, which lowers intracellular NAD/NADH ratio. NMN may partially reverse this effect, as shown in animal models [18]. For diabetic surgical patients on metformin (which is itself held 24 to 48 hours before contrast procedures per ACR guidelines), the combination with NMN adds no additional known surgical risk but introduces metabolic complexity.

Niacin (Nicotinic Acid)

High-dose niacin and NMN share a biosynthetic relationship: both feed the NAD pool via different routes. Concurrent use of prescription niacin (Niaspan, 500 to 2,000 mg/day) plus NMN or NR may produce supraphysiologic NAD levels. Niacin itself carries a known flushing and platelet-effect profile at high doses [19]. The combination warrants disclosure to the anesthesiologist.

Practical Pre-Surgery Protocol for Clinicians

The following framework consolidates pharmacokinetic data, mechanism-based risk reasoning, and general supplement perioperative guidelines into actionable steps.

Step 1: Identify the Procedure Risk Category

Low-risk procedures (skin biopsy, cataract surgery, minor dental): a 7-day hold is sufficient.

High-risk procedures (cardiac, hepatic, intracranial, major orthopedic, vascular): extend the hold to 14 days. Use the same cutoff applied to fish oil and vitamin E supplementation per ASA guidance [14].

Step 2: Confirm the Patient's Dose and Formulation

Doses at or below 250 mg/day carry lower theoretical risk than doses of 500 mg/day or above. Document the specific product, dose, and duration of use. Patients using combination NAD-booster stacks (NMN plus pterostilbene, NMN plus resveratrol) should stop all components simultaneously.

Step 3: Check for Concurrent Anticoagulants or Antiplatelets

If the patient is on any antiplatelet or anticoagulant agent, apply the 14-day hold regardless of procedure risk category and note the theoretical interaction in the pre-anesthesia assessment.

Step 4: Restart Criteria Post-Surgery

NMN and NR may be restarted 24 to 48 hours after surgery once oral intake is re-established, surgical hemostasis is confirmed, and the patient is not on post-operative anticoagulation for thromboprophylaxis at a dose that would make any antiplatelet effect clinically significant. Most patients can resume their standard dose by post-operative day 2.

What Patients Should Tell Their Surgical Team

Patients often do not classify NMN or NR as "medications" and may omit them from pre-operative questionnaires. Clinicians should ask explicitly about NAD precursors, longevity supplements, and any product containing the words "nicotinamide," "riboside," or "mononucleotide." A 2021 analysis of pre-operative supplement disclosure found that direct questioning increased supplement disclosure rates by 38 percentage points compared to written questionnaires alone [20].

Language Patients Can Use

Patients should tell their surgeon and anesthesiologist: "I take an NAD precursor supplement called [NMN/NR] at a dose of [X] mg per day. I have been taking it for [duration]. I stopped [date] ahead of this procedure."

Documentation in the Chart

The pre-anesthesia note should record the supplement name, dose, last date taken, and the reason for the hold. This protects both the patient and the provider if intraoperative bleeding or hemodynamic instability occurs.

Evidence Gaps and Future Research Needs

The perioperative literature on NMN and NR is nearly empty. The studies needed are:

1. A prospective cohort study measuring platelet aggregometry, PT, aPTT, and bleeding time in patients taking NMN 500 mg/day versus placebo for 4 weeks.
2. A pharmacodynamic study measuring eNOS activity and ex-vivo vascular reactivity during simulated anesthesia conditions in NMN-supplemented versus control subjects.
3. A perioperative RCT with intraoperative blood loss as a primary endpoint.

Until those studies exist, the 7-to-14-day hold framework remains the standard of care by analogy and precaution. The National Institutes of Health Office of Dietary Supplements maintains a database of ongoing supplement trials at ClinicalTrials.gov; as of early 2025, no registered trial addresses NMN or NR in the perioperative setting [21].