Patrick J. Merrill, MD
Internal Medicine Physician · Riverside, CA
Patrick J. Merrill, MD is an internal medicine physician with a practice address in Riverside, California, and NPI 1952460545, issued on Dec 8, 2006. Check the license (California G56039, as entered in NPPES) on the Medical Board of California; the Medicare figures below come from public CMS files.
- Name
- Patrick J. Merrill
- Credential
- MD
- Primary taxonomy
- Internal Medicine Physician 207R00000X
- License number
- G56039 CA
Self-reported in NPPES; status is on the state search - Practice location
- 10800 Magnolia Ave, Riverside, CA 92505
- Phone
- (909) 353-2000
- Enumerated
- Dec 8, 2006
- Record last updated
- Nov 29, 2021 (not updated in 5 years: call before relying on the address or phone)
- Entity
- Type 1 · individual
8 nearest internal medicine physician records → All 17,696 in California → Look up another NPI →
Also registered at 10800 Magnolia Ave
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Verify Patrick J. Merrill in five checks
- 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
- 2LicenseActive license and public ordersMedical Board of California
Search for license G56039Check the board - 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
- 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
- 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
95% fewer Medicare Part D claims than the average internal medicine physician in 2024
144 Medicare Part D claims for 135 beneficiaries, against an average of 3,176 among the 108,855 providers of this specialty who prescribed in Part D. Brand-name drugs were 70% of claims.
Most prescribed
- Paxlovid101 claims
- Paxlovid (Eua)24 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.
Patrick J. Merrill among 17,696 internal medicine physician records in California
Patrick J. Merrill, MD is one of 17,696 internal medicine physician records with a practice address in California. 79% 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 5% of them.
- NPI issued2006 · 5% of these records are older, 56% newer
- In a Medicare fileYes · 79% of these records are
- In the CMS Doctors and Clinicians fileNo · 63% of these records are
- Record last updated2021 · 61% of these records were not updated in five years or more
Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207R00000X and a California practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).
187 internal medicine physician records list a practice address in Riverside
They are 187 of the 13,893 NPPES records with a practice address in Riverside, and 17,696 internal medicine physician records in California.
All 17,696 in California → Every provider in Riverside → Internal Medicine Physician nationwide →
The 8 internal medicine physician records with the nearest ZIP codes
- Susan Diethelm, MDRiverside, CA 925051023185857
- Kathleen Fanning, MDRiverside, CA 925051427125335
- Thanh Hoang, MDRiverside, CA 925051174690994
- Ricardo Lim, MDRiverside, CA 925051336216159
- Iwan Ong, MDRiverside, CA 925051265416739
- Humera Rana, M.D.Riverside, CA 925051801982632
- Terence Shum, MDRiverside, CA 925051124195946
- Harneet Singh, MDRiverside, CA 925051114094943
Common questions
What is Patrick J. Merrill, MD's NPI number?
Patrick J. Merrill, MD's National Provider Identifier (NPI) is 1952460545, issued on Dec 8, 2006. An NPI identifies a provider in billing; it is not a license.
Where is Patrick J. Merrill, MD located?
The NPPES record lists a practice address at 10800 Magnolia Ave, Riverside, CA, 92505. Phone: (909) 353-2000. Providers update this record themselves, so call before visiting.
How can I verify Patrick J. Merrill, MD's license?
NPPES lists California license number G56039, as entered by the provider. Search the Medical Board of California at https://www.mbc.ca.gov/License-Verification/default.aspx. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.
How much does Patrick J. Merrill, MD prescribe under Medicare Part D?
In 2024, Patrick J. Merrill, MD had 144 Medicare Part D claims for 135 beneficiaries; the average among internal medicine physician prescribers was 3,176. 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.