Healthcare provider profile · identity verified

Guy P Van Der Werf, MD

Family Practice · ESTES PARK, CO · NPI 1538154257

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
LisinoprilLisinopril384106
Levothyroxine SodiumLevothyroxine Sodium32591
Atorvastatin CalciumAtorvastatin Calcium31593
Tamsulosin HclTamsulosin Hcl30999
PrednisonePrednisone253175
Amlodipine BesylateAmlodipine Besylate24772
Diclofenac SodiumDiclofenac Sodium19282
OmeprazoleOmeprazole17452
GabapentinGabapentin15854
Metoprolol SuccinateMetoprolol Succinate14642
Losartan PotassiumLosartan Potassium14245
Pravastatin SodiumPravastatin Sodium13335
HydrochlorothiazideHydrochlorothiazide13144
FinasterideFinasteride12939
Hydrocodone-AcetaminophenHydrocodone/Acetaminophen11827
AllopurinolAllopurinol11332
AlprazolamAlprazolam10526
Metformin Hcl ErMetformin Hcl9730
SimvastatinSimvastatin9731
Rosuvastatin CalciumRosuvastatin Calcium9430
AmoxicillinAmoxicillin9360
Trazodone HclTrazodone Hcl9231
EliquisApixaban8825
Metformin HclMetformin Hcl8725
Tramadol HclTramadol Hcl8021
Sulfamethoxazole-TrimethoprimSulfamethoxazole/Trimethoprim7551
FurosemideFurosemide7232
Zolpidem TartrateZolpidem Tartrate7121
Tizanidine HclTizanidine Hcl6747
Albuterol Sulfate HfaAlbuterol Sulfate6327
Fluoxetine HclFluoxetine Hcl5917
Oxycodone HclOxycodone Hcl59suppressed
Lisinopril-HydrochlorothiazideLisinopril/Hydrochlorothiazide5818
Pantoprazole SodiumPantoprazole Sodium5617
Alendronate SodiumAlendronate Sodium4916
MeloxicamMeloxicam4316
Paroxetine HclParoxetine Hcl43suppressed
Potassium ChloridePotassium Chloride4215
Memantine HclMemantine Hcl4011
Sertraline HclSertraline Hcl3912
Warfarin SodiumWarfarin Sodium3911
Ciprofloxacin HclCiprofloxacin Hcl3630
Citalopram HbrCitalopram Hydrobromide3614
Terazosin HclTerazosin Hcl35suppressed
Duloxetine HclDuloxetine Hcl3412
Venlafaxine Hcl ErVenlafaxine Hcl34suppressed
CephalexinCephalexin3120
Donepezil HclDonepezil Hcl3111
LorazepamLorazepam3114
SpironolactoneSpironolactone30suppressed
CarvedilolCarvedilol2911
DiazepamDiazepam28suppressed
Triamterene-HydrochlorothiazidTriamterene/Hydrochlorothiazid28suppressed
GlimepirideGlimepiride27suppressed
XareltoRivaroxaban27suppressed
EstradiolEstradiol26suppressed
Ondansetron OdtOndansetron2511
AzithromycinAzithromycin2417
Bupropion XlBupropion Hcl24suppressed
ClopidogrelClopidogrel Bisulfate24suppressed
Fluticasone PropionateFluticasone Propionate24suppressed
Amitriptyline HclAmitriptyline Hcl23suppressed
Nebivolol HclNebivolol Hcl23suppressed
PaxlovidNirmatrelvir/Ritonavir2323
ValacyclovirValacyclovir Hcl23suppressed
Olmesartan MedoxomilOlmesartan Medoxomil22suppressed
Ropinirole HclRopinirole Hcl22suppressed
SynthroidLevothyroxine Sodium22suppressed
Breo ElliptaFluticasone/Vilanterol21suppressed
LamotrigineLamotrigine21suppressed
Metoprolol TartrateMetoprolol Tartrate21suppressed
Escitalopram OxalateEscitalopram Oxalate20suppressed
Lantus SolostarInsulin Glargine,hum.Rec.Anlog20suppressed
Oxycodone-AcetaminophenOxycodone Hcl/Acetaminophen20suppressed
TopiramateTopiramate20suppressed
Dextroamphetamine-AmphetamineDextroamphetamine/Amphetamine19suppressed
Losartan-HydrochlorothiazideLosartan/Hydrochlorothiazide19suppressed
Montelukast SodiumMontelukast Sodium19suppressed
Quetiapine FumarateQuetiapine Fumarate19suppressed
Oxybutynin Chloride ErOxybutynin Chloride18suppressed
Benazepril HclBenazepril Hcl17suppressed
ColchicineColchicine17suppressed
OzempicSemaglutide17suppressed
Propranolol HclPropranolol Hcl17suppressed
Methylphenidate HclMethylphenidate Hcl16suppressed
OlanzapineOlanzapine15suppressed
Azelastine HclAzelastine Hcl14suppressed
Basaglar Kwikpen U-100Insulin Glargine,hum.Rec.Anlog14suppressed
LovastatinLovastatin14suppressed
CelecoxibCelecoxib13suppressed
ClonazepamClonazepam13suppressed
Diltiazem 24hr Er (Cd)Diltiazem Hcl13suppressed
Glipizide ErGlipizide13suppressed
JanuviaSitagliptin Phosphate13suppressed
Morphine Sulfate ErMorphine Sulfate13suppressed
Pramipexole DihydrochloridePramipexole Di-Hcl13suppressed
PregabalinPregabalin13suppressed
Triamcinolone AcetonideTriamcinolone Acetonide13suppressed
Bupropion Hcl SrBupropion Hcl12suppressed
Cyclobenzaprine HclCyclobenzaprine Hcl12suppressed
EzetimibeEzetimibe12suppressed
IbuprofenIbuprofen12suppressed
Nitrofurantoin Mono-MacroNitrofurantoin Monohyd/M-Cryst1211
ProgesteroneProgesterone, Micronized12suppressed
Testosterone CypionateTestosterone Cypionate12suppressed
Valsartan-HydrochlorothiazideValsartan/Hydrochlorothiazide12suppressed
AcyclovirAcyclovir11suppressed
AtenololAtenolol11suppressed
FenofibrateFenofibrate11suppressed
Hydroxyzine PamoateHydroxyzine Pamoate11suppressed
Nano 2nd Gen Pen NeedlePen Needle, Diabetic11suppressed
Ultra-Fine Nano Pen NeedlePen Needle, Diabetic11suppressed

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