Healthcare provider profile · identity verified

Mon-Ta Tsai, M.D.

Internal Medicine · MISSION VIEJO, CA · NPI 1427019231

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
Losartan PotassiumLosartan Potassium366101
Amlodipine BesylateAmlodipine Besylate32390
Rosuvastatin CalciumRosuvastatin Calcium31897
Atorvastatin CalciumAtorvastatin Calcium26982
Metformin HclMetformin Hcl16550
Tamsulosin HclTamsulosin Hcl13441
Metoprolol SuccinateMetoprolol Succinate11438
LisinoprilLisinopril10128
HydrochlorothiazideHydrochlorothiazide9926
FarxigaDapagliflozin Propanediol8624
AllopurinolAllopurinol7121
OmeprazoleOmeprazole7128
Pravastatin SodiumPravastatin Sodium6922
Levothyroxine SodiumLevothyroxine Sodium6721
Alendronate SodiumAlendronate Sodium6423
Metoprolol TartrateMetoprolol Tartrate6418
FinasterideFinasteride5819
PrednisonePrednisone5541
GabapentinGabapentin5421
JanuviaSitagliptin Phosphate5313
FurosemideFurosemide5017
Metformin Hcl ErMetformin Hcl4917
MeloxicamMeloxicam4819
JardianceEmpagliflozin4717
AtenololAtenolol4512
EzetimibeEzetimibe4515
CarvedilolCarvedilol4412
ClopidogrelClopidogrel Bisulfate4316
Zolpidem TartrateZolpidem Tartrate3819
Glipizide ErGlipizide36suppressed
ValsartanValsartan35suppressed
AzithromycinAzithromycin3434
FamotidineFamotidine3312
Pantoprazole SodiumPantoprazole Sodium30suppressed
Omega-3 Acid Ethyl EstersOmega-3 Acid Ethyl Esters28suppressed
Olmesartan MedoxomilOlmesartan Medoxomil27suppressed
Losartan-HydrochlorothiazideLosartan/Hydrochlorothiazide26suppressed
XareltoRivaroxaban26suppressed
Potassium ChloridePotassium Chloride24suppressed
Triamcinolone AcetonideTriamcinolone Acetonide2317
Amoxicillin-Clavulanate PotassAmoxicillin/Potassium Clav2218
CelecoxibCelecoxib22suppressed
Ciprofloxacin HclCiprofloxacin Hcl2218
EliquisApixaban21suppressed
Sildenafil CitrateSildenafil Citrate21suppressed
SimvastatinSimvastatin21suppressed
EntecavirEntecavir20suppressed
Lisinopril-HydrochlorothiazideLisinopril/Hydrochlorothiazide20suppressed
Oxybutynin Chloride ErOxybutynin Chloride20suppressed
GlimepirideGlimepiride19suppressed
PaxlovidNirmatrelvir/Ritonavir1919
Trazodone HclTrazodone Hcl1913
Hydrocodone-AcetaminophenHydrocodone/Acetaminophen18suppressed
Ropinirole HclRopinirole Hcl18suppressed
AlprazolamAlprazolam16suppressed
Buspirone HclBuspirone Hcl15suppressed
Hydralazine HclHydralazine Hcl15suppressed
ClonazepamClonazepam14suppressed
Sertraline HclSertraline Hcl14suppressed
Tramadol HclTramadol Hcl14suppressed
Triamterene-HydrochlorothiazidTriamterene/Hydrochlorothiazid14suppressed
Venlafaxine Hcl ErVenlafaxine Hcl14suppressed
Escitalopram OxalateEscitalopram Oxalate13suppressed
FenofibrateFenofibrate12suppressed
NystatinNystatin12suppressed
ClotrimazoleClotrimazole11suppressed
TemazepamTemazepam11suppressed

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