Healthcare provider profile · identity verified

Donald H Grenz, MD

Internal Medicine · BISMARCK, ND · NPI 1699720995

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

Brand	Generic	Claims	Beneficiaries
Amlodipine Besylate	Amlodipine Besylate	1021	272
Rosuvastatin Calcium	Rosuvastatin Calcium	868	226
Atorvastatin Calcium	Atorvastatin Calcium	658	178
Omeprazole	Omeprazole	493	142
Losartan Potassium	Losartan Potassium	492	139
Metformin Hcl	Metformin Hcl	491	112
Levothyroxine Sodium	Levothyroxine Sodium	490	117
Lisinopril	Lisinopril	458	119
Metoprolol Succinate	Metoprolol Succinate	455	116
Hydrochlorothiazide	Hydrochlorothiazide	409	110
Tamsulosin Hcl	Tamsulosin Hcl	351	98
Pantoprazole Sodium	Pantoprazole Sodium	268	71
Simvastatin	Simvastatin	265	72
Furosemide	Furosemide	260	75
Meloxicam	Meloxicam	229	58
Allopurinol	Allopurinol	226	59
Eliquis	Apixaban	220	47
Lisinopril-Hydrochlorothiazide	Lisinopril/Hydrochlorothiazide	211	52
Sertraline Hcl	Sertraline Hcl	203	52
Alendronate Sodium	Alendronate Sodium	195	55
Metoprolol Tartrate	Metoprolol Tartrate	188	53
Lantus Solostar	Insulin Glargine,hum.Rec.Anlog	178	35
Losartan-Hydrochlorothiazide	Losartan/Hydrochlorothiazide	176	47
Pravastatin Sodium	Pravastatin Sodium	170	43
Jardiance	Empagliflozin	168	33
Metformin Hcl Er	Metformin Hcl	167	46
Warfarin Sodium	Warfarin Sodium	162	23
Famotidine	Famotidine	131	28
Albuterol Sulfate Hfa	Albuterol Sulfate	128	49
Potassium Chloride	Potassium Chloride	121	30
Citalopram Hbr	Citalopram Hydrobromide	117	24
Ezetimibe	Ezetimibe	113	28
Montelukast Sodium	Montelukast Sodium	107	28
Finasteride	Finasteride	101	30
Gabapentin	Gabapentin	94	28
Clopidogrel	Clopidogrel Bisulfate	92	26
Lorazepam	Lorazepam	89	30
Synthroid	Levothyroxine Sodium	86	23
Gemfibrozil	Gemfibrozil	85	17
Olmesartan Medoxomil	Olmesartan Medoxomil	83	22
Zolpidem Tartrate	Zolpidem Tartrate	77	31
Escitalopram Oxalate	Escitalopram Oxalate	76	22
Diltiazem 24hr Er (Cd)	Diltiazem Hcl	75	21
Celecoxib	Celecoxib	71	30
Trazodone Hcl	Trazodone Hcl	71	18
Atenolol	Atenolol	66	18
Basaglar Kwikpen U-100	Insulin Glargine,hum.Rec.Anlog	66	12
Esomeprazole Magnesium	Esomeprazole Magnesium	66	14
Humalog Kwikpen U-100	Insulin Lispro	65	15
Xarelto	Rivaroxaban	65	21
Boostrix Tdap	Diphth,pertuss(Acell),tet Vac	63	62
Ozempic	Semaglutide	60	suppressed
Cyclobenzaprine Hcl	Cyclobenzaprine Hcl	59	24
Duloxetine Hcl	Duloxetine Hcl	58	13
Carvedilol	Carvedilol	57	18
Prednisone	Prednisone	57	25
Ramipril	Ramipril	57	16
Donepezil Hcl	Donepezil Hcl	56	16
Propranolol Hcl	Propranolol Hcl	55	13
Glimepiride	Glimepiride	51	14
Januvia	Sitagliptin Phosphate	51	13
Olmesartan-Hydrochlorothiazide	Olmesartan/Hydrochlorothiazide	50	12
Isosorbide Mononitrate Er	Isosorbide Mononitrate	49	suppressed
Doxazosin Mesylate	Doxazosin Mesylate	46	13
Triamterene-Hydrochlorothiazid	Triamterene/Hydrochlorothiazid	44	11
Alprazolam	Alprazolam	43	14
Mirtazapine	Mirtazapine	42	11
Spironolactone	Spironolactone	42	14
Tramadol Hcl	Tramadol Hcl	42	17
Ciprofloxacin Hcl	Ciprofloxacin Hcl	41	33
Fluticasone Propionate	Fluticasone Propionate	38	13
Ropinirole Hcl	Ropinirole Hcl	38	suppressed
Symbicort	Budesonide/Formoterol Fumarate	37	suppressed
Trulicity	Dulaglutide	37	suppressed
Clonazepam	Clonazepam	36	suppressed
Paroxetine Hcl	Paroxetine Hcl	36	suppressed
Sumatriptan Succinate	Sumatriptan Succinate	35	suppressed
Venlafaxine Hcl Er	Venlafaxine Hcl	35	suppressed
Fluoxetine Hcl	Fluoxetine Hcl	33	suppressed
Ultra-Fine Short Pen Needle	Pen Needle, Diabetic	33	11
Amoxicillin	Amoxicillin	32	24
Lansoprazole	Lansoprazole	32	suppressed
Fenofibrate	Fenofibrate Nanocrystallized	31	suppressed
Insulin Lispro Kwikpen U-100	Insulin Lispro	31	suppressed
Jantoven	Warfarin Sodium	31	suppressed
Terazosin Hcl	Terazosin Hcl	31	suppressed
Tresiba Flextouch U-200	Insulin Degludec	31	suppressed
Chlorthalidone	Chlorthalidone	30	suppressed
Janumet	Sitagliptin Phos/Metformin Hcl	30	suppressed
Bupropion Xl	Bupropion Hcl	29	suppressed
Hydrocodone-Acetaminophen	Hydrocodone/Acetaminophen	28	15
Oxybutynin Chloride Er	Oxybutynin Chloride	28	suppressed
Amlodipine Besylate-Benazepril	Amlodipine Besylate/Benazepril	26	suppressed
Novolog Flexpen	Insulin Aspart	26	suppressed
Tresiba Flextouch U-100	Insulin Degludec	26	suppressed
Ultra-Fine Mini Pen Needle	Pen Needle, Diabetic	26	suppressed
Bisoprolol-Hydrochlorothiazide	Bisoprolol/Hydrochlorothiazide	25	suppressed
Cefdinir	Cefdinir	25	23
Fluticasone-Salmeterol	Fluticasone Propion/Salmeterol	25	suppressed
Verapamil Er	Verapamil Hcl	25	suppressed
Budesonide-Formoterol Fumarate	Budesonide/Formoterol Fumarate	24	suppressed
Triamcinolone Acetonide	Triamcinolone Acetonide	24	19
Victoza 3-Pak	Liraglutide	24	suppressed
Amoxicillin-Clavulanate Potass	Amoxicillin/Potassium Clav	23	18
Benazepril Hcl	Benazepril Hcl	23	suppressed
Diltiazem 24hr Er	Diltiazem Hcl	23	suppressed
Mounjaro	Tirzepatide	22	suppressed
Nano 2nd Gen Pen Needle	Pen Needle, Diabetic	22	11
Pramipexole Dihydrochloride	Pramipexole Di-Hcl	22	suppressed
Pregabalin	Pregabalin	22	suppressed
Clotrimazole-Betamethasone	Clotrimazole/Betamethasone Dip	21	14
Dutasteride	Dutasteride	21	suppressed
Valsartan-Hydrochlorothiazide	Valsartan/Hydrochlorothiazide	21	suppressed
Propranolol Hcl Er	Propranolol Hcl	20	suppressed
Ultra-Fine Nano Pen Needle	Pen Needle, Diabetic	20	suppressed
Colchicine	Colchicine	19	suppressed
Mupirocin	Mupirocin	19	14
Spiriva Respimat	Tiotropium Bromide	19	suppressed
Toujeo Solostar	Insulin Glargine,hum.Rec.Anlog	19	suppressed
Azithromycin	Azithromycin	18	16
Farxiga	Dapagliflozin Propanediol	18	suppressed
Valacyclovir	Valacyclovir Hcl	18	11
Amitriptyline Hcl	Amitriptyline Hcl	17	suppressed
Diclofenac Sodium	Diclofenac Sodium	17	suppressed
Fenofibrate	Fenofibrate	17	suppressed
Rybelsus	Semaglutide	17	suppressed
Anoro Ellipta	Umeclidinium Brm/Vilanterol Tr	16	suppressed
Carbidopa-Levodopa	Carbidopa/Levodopa	16	suppressed
Ezetimibe-Simvastatin	Ezetimibe/Simvastatin	16	suppressed
Klor-Con M20	Potassium Chloride	16	suppressed
Memantine Hcl	Memantine Hcl	16	suppressed
Nystatin	Nystatin	16	suppressed
Oxybutynin Chloride	Oxybutynin Chloride	16	suppressed
Telmisartan	Telmisartan	16	suppressed
Verapamil Sr	Verapamil Hcl	16	suppressed
Breo Ellipta	Fluticasone/Vilanterol	15	suppressed
Cholestyramine	Cholestyramine (With Sugar)	15	suppressed
Enalapril Maleate	Enalapril Maleate	15	suppressed
Olmesartan-Amlodipine-Hctz	Olmesartan/Amlodipin/Hcthiazid	15	suppressed
Primidone	Primidone	15	suppressed
Toujeo Max Solostar	Insulin Glargine,hum.Rec.Anlog	15	suppressed
Venlafaxine Hcl	Venlafaxine Hcl	15	suppressed
Ipratropium Bromide	Ipratropium Bromide	14	suppressed
Lactulose	Lactulose	14	suppressed
Vascepa	Icosapent Ethyl	14	suppressed
Diazepam	Diazepam	13	suppressed
Glyxambi	Empagliflozin/Linagliptin	13	suppressed
Hydrocortisone	Hydrocortisone	13	suppressed
Invokamet	Canagliflozin/Metformin Hcl	13	suppressed
Nitroglycerin	Nitroglycerin	13	12
Ondansetron Hcl	Ondansetron Hcl	13	suppressed
Rizatriptan	Rizatriptan Benzoate	13	suppressed
Trelegy Ellipta	Fluticasone/Umeclidin/Vilanter	13	suppressed
Clonidine Hcl	Clonidine Hcl	12	suppressed
Comfort Ez Pen Needle	Pen Needle, Diabetic	12	suppressed
Creon	Lipase/Protease/Amylase	12	suppressed
Doxepin Hcl	Doxepin Hcl	12	suppressed
Estradiol (Twice Weekly)	Estradiol	12	suppressed
Hydroxychloroquine Sulfate	Hydroxychloroquine Sulfate	12	suppressed
Sucralfate	Sucralfate	12	suppressed
Topiramate	Topiramate	12	suppressed
Torsemide	Torsemide	12	suppressed
Bupropion Hcl Sr	Bupropion Hcl	11	suppressed
Cevimeline Hcl	Cevimeline Hcl	11	suppressed
Ventolin Hfa	Albuterol Sulfate	11	suppressed
Victoza 2-Pak	Liraglutide	11	suppressed

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.

Year	General Payments	Main payer	Explicit products	Company overlaps	Part D coverage
2025	—	—	—	—	—
2024	—	—	—	—	Complete

Questions to ask

Questions you could discuss with your doctor

Are there reasonable alternatives I should understand when we discuss treatment options?
How should I interpret the industry-payment records shown here in the context of my care?

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

Sources and limitations

How to read this page

Payment and Medicare prescribing data can cover different years; every comparison shows both years explicitly.
Part D does not represent a doctor’s entire practice; it excludes many patients and is subject to CMS public-release thresholds.
Company–drug relationships must have an auditable source, a precise relationship type, and a valid evidence period. Unresolved mappings are not published.
Generic drug claims are not attributed to a specific manufacturer without manufacturer-level evidence.
When a source extract is incomplete, missing rows are never treated as proof of no payments or no prescriptions.

Loaded source releases

Dataset	Year	Publication	Source
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