Mark S. O'Brien, MD
Family Medicine Physician · Carmel, IN
Mark S. O'Brien, MD is a family medicine physician with a practice address in Carmel, Indiana, and NPI 1124129267, issued on Sep 25, 2006. Check the license (Indiana 01037757A, as entered in NPPES) on the Medical Licensing Board of Indiana; the Medicare figures below come from public CMS files.
- Name
- Mark S. O'Brien
- Credential
- MD
- Primary taxonomy
- Family Medicine Physician 207Q00000X
- License number
- 01037757A IN
Self-reported in NPPES; status is on the state search - Practice location
- 11725 N Illinois St Ste 250, Carmel, IN 46032
- Phone
- (317) 688-5300
- Enumerated
- Sep 25, 2006
- Record last updated
- Jan 6, 2021 (not updated in 5 years: call before relying on the address or phone)
- Fax
- (317) 688-5313
- Medicaid ID
- 200033390 IN
- Medicare enrollment
- Enrolled (PECOS I20090330000617); accepts Medicare assignment
- Medical or professional school
- Indiana University School Of Medicine, 1988
- Entity
- Type 1 · individual
8 nearest family medicine physician records → All 3,506 in Indiana → Look up another NPI →
Verify Mark S. O'Brien in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Licensing Board of Indiana
Search for license 01037757ACheck the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
65% more Medicare Part D claims than the average family medicine physician in 2024
5,865 Medicare Part D claims for 444 beneficiaries, against an average of 3,544 among the 117,163 providers of this specialty who prescribed in Part D. Brand-name drugs were 9% of claims. 43 claims were for opioids.
Most prescribed
- Atorvastatin Calcium686 claims
- Amlodipine Besylate355 claims
- Losartan Potassium262 claims
- Lisinopril233 claims
- Metoprolol Succinate221 claims
- Levothyroxine Sodium205 claims
Source: CMS Medicare Part D Prescribers by Provider and Drug, 2024 (data.cms.gov). Part D covers prescriptions for Medicare patients only; drugs with fewer than 11 claims are not published.
Bills Medicare through 2 group practices
- Indiana University Health Care Associates IncCarmel, IN
- IU Health Medical Group LLCIndianapolis, IN
Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).
Mark S. O'Brien among 3,506 family medicine physician records in Indiana
Mark S. O'Brien, MD is one of 3,506 family medicine physician records with a practice address in Indiana. 81% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2006, is newer than 19% of them.
- NPI issued2006 · 19% of these records are older, 46% newer
- In a Medicare fileYes · 81% of these records are
- In the CMS Doctors and Clinicians fileYes · 63% of these records are
- Graduated1988 · median 2005 among the 2,196 with a school on file
- Record last updated2021 · 48% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207Q00000X and a Indiana practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
73 family medicine physician records list a practice address in Carmel
They are 73 of the 3,727 NPPES records with a practice address in Carmel, and 3,506 family medicine physician records in Indiana.
All 3,506 in Indiana → Every provider in Carmel → Family Medicine Physician nationwide →
The 8 family medicine physician records with the nearest ZIP codes
- Aaron Ashabraner, MDCarmel, IN 460321407841513
- Jeffrey Collier, MDCarmel, IN 460321942283833
- Sanju Daftari, MDCarmel, IN 460321013955764
- Adrienne Gomez, M.D.Carmel, IN 460321568440634
- James Horton, MDCarmel, IN 460321164407326
- Brian Howse, MDCarmel, IN 460321669454260
- Peiyi Hu, MDCarmel, IN 460321053334854
- Andrew McLaren, MDCarmel, IN 460321710960844
Common questions
What is Mark S. O'Brien, MD's NPI number?
Mark S. O'Brien, MD's National Provider Identifier (NPI) is 1124129267, issued on Sep 25, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Mark S. O'Brien, MD located?
The NPPES record lists a practice address at 11725 N Illinois St Ste 250, Carmel, IN, 46032. Phone: (317) 688-5300. Providers update this record themselves, so call before visiting.
How can I verify Mark S. O'Brien, MD's license?
NPPES lists Indiana license number 01037757A, as entered by the provider. Search the Medical Licensing Board of Indiana at https://www.in.gov/pla/professions/physicians-home/. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Mark S. O'Brien, MD prescribe under Medicare Part D?
In 2024, Mark S. O'Brien, MD had 5,865 Medicare Part D claims for 444 beneficiaries; the average among family medicine physician prescribers was 3,544. Part D covers Medicare prescriptions only.
Source: CMS National Plan and Provider Enumeration System (NPPES), file of Aug 9, 2026 (NPPES files on CMS.gov); NUCC Health Care Provider Taxonomy. Medicare files from data.cms.gov. An NPI identifies who bills; it is not a license.
Figures on PlainDoctor are read from the federal files each page names (CMS NPPES, Medicare Part D, MIPS, Open Payments; the HHS-OIG exclusion list only as counts) and from Census population estimates, with the file date shown beside them. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of Aug 9, 2026.