Healthcare provider profile · identity verified

Nathan C Grunwald, MD

Family Practice · MENASHA, WI · NPI 1073549887

Profile state: partd only Open Payments: 2025 Medicare Part D: 2024 Last identity check: 2026-08-10 Page data build: 2026-08-12

Verified facts

What the public records show

We did not find matching Open Payments records for this doctor in 2025.

These records do not establish that a payment influenced prescribing or medical care.

Payment overview · 2025

General Payments

We did not find matching Open Payments records for this doctor in the selected program year.

Separate record types

Research & Ownership

Research Payments (direct recipient): not present in the loaded data

Associated Research Funding (for example, named PI): not present in the loaded data

Ownership / Investment: not present in the loaded data

These categories are never added into the General Payments headline. Associated research funding must not be described as money the doctor personally received unless the source record supports that conclusion.

Analysis 1 · Payment-linked products

Products named in Open Payments records

No payment-linked product analysis is available because no matching General Payment records were found for the selected year.

Public prescribing for products named in payments

There is no explicit payment-product set available for a Part D comparison.

The presence of the same drug in both datasets does not show that a payment caused or influenced a prescription.

Analysis 2 · Same-company prescribing overlap

Drugs reported in other payments from the same company that also appear in Medicare Part D

This analysis is independent from products named on this doctor’s individual payment records. A row appears only when the exact Open Payments reporting entity paid this doctor, that same reporting entity reported the drug or biological on at least 10 loaded General Payment records involving at least 2 distinct recipient NPIs, and this doctor has the same non-generic brand in public Part D data. This does not mean the company owns or manufactures the drug.

There is no payer-company set available for this comparison.

These facts do not show that a payment was for the drug, that the company owns or manufactures the drug, or that a payment caused or influenced prescribing.

Public Medicare Part D data

Provider-and-drug rows loaded for 2024

BrandGenericClaimsBeneficiaries
Atorvastatin CalciumAtorvastatin Calcium797213
Amlodipine BesylateAmlodipine Besylate501141
Losartan PotassiumLosartan Potassium29186
OmeprazoleOmeprazole24570
Metoprolol SuccinateMetoprolol Succinate23866
LisinoprilLisinopril23470
Levothyroxine SodiumLevothyroxine Sodium22948
SimvastatinSimvastatin16343
HydrochlorothiazideHydrochlorothiazide15543
Rosuvastatin CalciumRosuvastatin Calcium14844
Metformin HclMetformin Hcl13740
Metoprolol TartrateMetoprolol Tartrate12933
GabapentinGabapentin12729
Montelukast SodiumMontelukast Sodium11436
Tamsulosin HclTamsulosin Hcl10533
FurosemideFurosemide10030
EliquisApixaban9823
Pantoprazole SodiumPantoprazole Sodium8622
Trazodone HclTrazodone Hcl8319
AllopurinolAllopurinol7721
Warfarin SodiumWarfarin Sodium7713
Albuterol Sulfate HfaAlbuterol Sulfate7635
CarvedilolCarvedilol7622
Fluticasone PropionateFluticasone Propionate7239
Metformin Hcl ErMetformin Hcl7225
AtenololAtenolol7118
Pioglitazone HclPioglitazone Hcl6720
Fluoxetine HclFluoxetine Hcl6315
Lisinopril-HydrochlorothiazideLisinopril/Hydrochlorothiazide6319
Citalopram HbrCitalopram Hydrobromide6220
Lantus SolostarInsulin Glargine,hum.Rec.Anlog5715
GlimepirideGlimepiride5317
MeloxicamMeloxicam5026
Sertraline HclSertraline Hcl5011
Potassium ChloridePotassium Chloride4915
Memantine HclMemantine Hcl47suppressed
SpironolactoneSpironolactone4716
Bupropion XlBupropion Hcl4615
Alendronate SodiumAlendronate Sodium4214
ClopidogrelClopidogrel Bisulfate4011
Oxycodone HclOxycodone Hcl37suppressed
Venlafaxine Hcl ErVenlafaxine Hcl3711
Amitriptyline HclAmitriptyline Hcl36suppressed
JardianceEmpagliflozin36suppressed
Hydrocodone-AcetaminophenHydrocodone/Acetaminophen35suppressed
Donepezil HclDonepezil Hcl34suppressed
Fluticasone-SalmeterolFluticasone Propion/Salmeterol3414
Oxycodone-AcetaminophenOxycodone Hcl/Acetaminophen33suppressed
Triamcinolone AcetonideTriamcinolone Acetonide3328
Hydralazine HclHydralazine Hcl32suppressed
TrulicityDulaglutide32suppressed
Hydroxyzine HclHydroxyzine Hcl31suppressed
Sumatriptan SuccinateSumatriptan Succinate31suppressed
Buspirone HclBuspirone Hcl30suppressed
JanuviaSitagliptin Phosphate30suppressed
Ropinirole HclRopinirole Hcl30suppressed
ClonazepamClonazepam29suppressed
Duloxetine HclDuloxetine Hcl28suppressed
Escitalopram OxalateEscitalopram Oxalate27suppressed
AlprazolamAlprazolam25suppressed
EzetimibeEzetimibe25suppressed
LovastatinLovastatin24suppressed
Benazepril HclBenazepril Hcl23suppressed
Paroxetine HclParoxetine Hcl23suppressed
Terazosin HclTerazosin Hcl22suppressed
AcyclovirAcyclovir20suppressed
Doxazosin MesylateDoxazosin Mesylate20suppressed
FamotidineFamotidine20suppressed
Diclofenac SodiumDiclofenac Sodium19suppressed
ChlorthalidoneChlorthalidone18suppressed
Enalapril MaleateEnalapril Maleate18suppressed
Klor-Con M20Potassium Chloride18suppressed
NitroglycerinNitroglycerin1813
XareltoRivaroxaban18suppressed
Zolpidem TartrateZolpidem Tartrate18suppressed
BumetanideBumetanide17suppressed
FinasterideFinasteride17suppressed
GlipizideGlipizide17suppressed
OzempicSemaglutide17suppressed
Pravastatin SodiumPravastatin Sodium17suppressed
Spiriva RespimatTiotropium Bromide17suppressed
MyrbetriqMirabegron16suppressed
Pramipexole DihydrochloridePramipexole Di-Hcl16suppressed
GemfibrozilGemfibrozil15suppressed
Losartan-HydrochlorothiazideLosartan/Hydrochlorothiazide14suppressed
MethylprednisoloneMethylprednisolone1414
BaclofenBaclofen13suppressed
Diltiazem 24hr Er (Cd)Diltiazem Hcl13suppressed
HydrocortisoneHydrocortisone12suppressed
Wixela InhubFluticasone Propion/Salmeterol12suppressed
Meclizine HclMeclizine Hcl11suppressed
PregabalinPregabalin11suppressed
ValacyclovirValacyclovir Hcl11suppressed

Timeline

Payment and prescribing data by year

Open Payments and Medicare Part D may refer to different years. They are shown separately rather than aligned as if they describe the same period.

YearGeneral PaymentsMain payerExplicit productsCompany overlapsPart D coverage
2025
2024 Complete

Questions to ask

Questions you could discuss with your doctor

These are general questions generated from reviewed templates. They are not personalized medical advice.

Sources and limitations

How to read this page

Loaded source releases

DatasetYearPublicationSource
CMS Open Payments — General Payments 2025 2026-06-30 Original source
Medicare Part D Prescribers by Provider and Drug 2024 2026-05-06 Original source
NPPES Data Dissemination V2 current / reference data 2026-08-10 Original source

Methodology version: 2.1

Editorial template version: 2.4

Product contract version: 2.0

Schema version: 0.7.0

Page data build: 2026-08-12T23:34:59.370714+00:00

Publication policy: eligible for indexing after public-launch controls are enabled

Full methodology · Questions & answers · Report a possible error