2026 NPPES data Gastroenterology Physician NPI 1346347028 M.D.
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GREGORY HARMON, M.D.

Gastroenterology Physician in HARBOR CITY, California. CMS National Plan and Provider Enumeration System profile including specialty classification, practice address, and Medicare prescribing data when reported.

Federal data — no proprietary rating. PlainDoctor publishes the actual CMS NPPES and Medicare records — NPI registration, specialty, practice location, and prescribing data — without a composite score or editorial opinion on top. Every field traces to a federal source.
Prescribing volume
615
Medicare Part D claims · 257 beneficiaries · Gastroenterology Physician avg: 833
Generic prescribing
85%
generic claims · 15% brand-name · higher generic rates reduce patient out-of-pocket costs
Industry payments
$16.75
1 payments · CMS Open Payments (Sunshine Act)

What the federal data shows

GREGORY HARMON, M.D. filed 615 Medicare Part D claims in 2023 as a Gastroenterology Physician in HARBOR CITY, California, prescribing 85% generic.

615
Part D claims, 2023
85%
generic prescribing
Likely
board-certified (heuristic)

Every figure on this page comes straight from federal CMS records (NPPES, Medicare Part D, MIPS, Open Payments) — no proprietary rating or editorial opinion is applied.

GREGORY HARMON, M.D.'s Medicare Part D volume vs every U.S. prescriber

Total Medicare Part D claims, 2023 — across all CMS prescribers nationally

615 Top 31% higher than 69% of 1,370,886 prescribers

0–200: 670,926 prescribers (49%). Below this entry. 200–400: 182,923 prescribers (13%). Below this entry. 400–600: 90,619 prescribers (7%). Below this entry. 600–800: 56,224 prescribers (4%). This entry sits in this band. 800–1,000: 40,919 prescribers (3%). Above this entry. 1,000–1,200: 31,827 prescribers (2%). Above this entry. 1,200–1,400: 26,224 prescribers (2%). Above this entry. 1,400–1,600: 21,710 prescribers (2%). Above this entry. 1,600–1,800: 19,072 prescribers (1%). Above this entry. 1,800–2,000: 16,451 prescribers (1%). Above this entry. 2,000–2,200: 213,991 prescribers (16%). Above this entry. This provider 0 2K+ every Part D prescriber (claims/yr), bucketed by value

Each bar is a band; taller bars hold more prescribers. The dashed line + filled bar mark this entry. Hover or tap any bar for its full count, share, and where it sits relative to this entry.

Source CMS Medicare Part D Prescriber Public Use File · 2023

Board certification likely (heuristic — not verified)

GREGORY HARMON, M.D. practices in an ABMS-board-eligible specialty and shows active CMS Medicare participation + 1 hospital affiliation — signals consistent with board-certified status. For verified board certification, see CertificationMatters.org (the official ABMS public lookup).

What does the federal data show about GREGORY HARMON, M.D.?

Quality data not reported

NPI registry status

Active

Issued 09/17/2006

NPI 1346347028

Primary specialty

Gastroenterology Physician

Mid-sized

16,567 US NPIs in this specialty

Medicare Part D claims

615 26% vs specialty avg

2023 prescription claims

Specialty avg: 833

Specialty distribution in California

How Gastroenterology Physician compares to other specialties among California providers

California providers

Gastroenterology Physician share within California

1. Gastroenterology Physician42%2. Internal medicine21%3. Family medicine17%4. Surgical12%5. Pediatric8%
Gastroenterology Physician share within California

Specialty board-certification context

Estimated specialty board-certified rate — Gastroenterology Physician (ABMS / AOA reference)

Quality data not reported
Est. board-certified rate
78%
Gastroenterology Physician ABMS/AOA estimate

Est. board-certified rate (Gastroenterology Physician) — ABMS / AOA estimate

0%100%78%
Est. board-certified rate (Gastroenterology Physician) — ABMS / AOA estimate

The Merit-based Incentive Payment System (MIPS) scores providers 0–100 across four performance categories: Quality, Cost, Promoting Interoperability, and Improvement Activities, weighted under 42 CFR §414.1380. Reporting is voluntary for many small practices, so absence of a MIPS score is not a quality signal.

Board certification through an ABMS or AOA member board signals voluntary post-licensure examination plus continuous Maintenance of Certification cycles. Verify any individual provider's status through certificationmatters.org (ABMS) or osteopathic.org (AOA).

GREGORY HARMON, M.D. appears in the CMS NPPES registry as a Gastroenterology Physician provider holding M.D. credentials at 25825 VERMONT AVE, HARBOR CITY, CA, 90710, with a listed phone of (310) 325-5111. NPI 1346347028 was issued on 09/17/2006. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what HARMON most recently submitted to CMS rather than a vetted directory listing, which is why patients should always confirm the practice is still at this location before scheduling.

Medicare Part D records for calendar year 2023 show 615 prescription claims written by this provider, covering 257 Medicare beneficiaries and totaling roughly $469K in drug spend, split 15% brand-name and 85% generic by claim count. These figures capture only Medicare Part D — commercial insurance, Medicaid, and cash-pay prescriptions are not included, and any drug-beneficiary cell under 11 is suppressed by CMS for patient privacy.

Gastroenterology Physician is a mid-sized specialty nationwide, with 16,567 enrolled providers across 54 states and an average of 833 Part D claims per prescriber, so the context for interpreting these metrics differs meaningfully from a primary-care baseline. Important: PlainDoctor is a directory of publicly available government data, not medical advice, a malpractice database, or a quality rating. Inclusion here does not imply a recommendation, and absence of complaints or sanctions on this page does not mean none exist — always verify credentials through the NPPES NPI Registry, your state medical board, and the ABMS or AOA before making healthcare decisions.

Practice Address

25825 VERMONT AVE
HARBOR CITY, CA 90710

Provider Details

NPI 1346347028
Specialty Gastroenterology Physician
Credentials M.D.
Gender Male
NPI Issued 09/17/2006

Hospital and facility affiliations

Facilities where GREGORY HARMON, M.D. bills Medicare from. Star ratings (1-5) are CMS Hospital Compare's "Hospital overall rating" — a composite of mortality, readmission, patient experience, safety, timely care, and efficient use of medical imaging measures. Source: CMS Care Compare.

PROVIDENCE MEDICAL INSTITUTE
LAGUNA NIGUEL, CA

Affiliations sourced from CMS Doctors and Clinicians National Downloadable File; hospital ratings from CMS Hospital General Information dataset (cross-referenced by facility name + state).

Industry payments received (2024) — CMS Open Payments transparency data

The federal Physician Payments Sunshine Act (part of the Affordable Care Act) requires drug and medical-device manufacturers + group purchasing organizations to publicly report payments and other transfers of value to physicians and teaching hospitals. The data below covers 2024 for GREGORY HARMON, M.D.. Source: openpaymentsdata.cms.gov.

Total received

$17

Largest payer

ABBVIE INC.

Most common payment type

Food and Beverage

Industry payments are not necessarily indicators of bias — they include research funding, consulting fees for evidence-based work, royalties for inventions, food at conferences, and similar items. The disclosure exists for transparency. Read our methodology for how we interpret this data.

License & disciplinary context — California MBC 2023 annual report

Aggregate state board data only — NOT a determination of any individual provider's status. The figures below describe statewide disciplinary activity across all ~150K California medical licensees in 2023 — they are NOT specific to GREGORY HARMON, M.D.. To verify GREGORY HARMON, M.D.'s current license status, search the MBC public license lookup directly, or check the Federation of State Medical Boards (FSMB) verification service.

576
Total board actions, California 2023
Across 556 cases
3.84
Actions per 1,000 licensees
California statewide rate
probation
Most common action type
186 cases

MBC publishes annual disciplinary statistics as part of public-record reporting under each state's Administrative Procedure Act. See the full breakdown by action type and year on the California disciplinary trends page. Cross-checked against FSMB U.S. Medical Regulatory Trends.

Brand vs generic prescribing mix · Typical

GREGORY HARMON, M.D. — brand share 15.0%
Specialty average (est.)

15% brand-name claims vs 85% generic, on 615 2023 Medicare Part D claims.

The federal Medicare Part D Generic Dispensing Rate national benchmark sits near 90% generic / 10% brand for primary-care prescribers, per CMS Office of the Actuary 2024 estimates. Higher brand share is common in specialty prescribing where generic equivalents are not available.

Medicare Part D Prescribing Data

CMS Medicare Part D prescriber-level data for calendar year 2023.

615
Total Claims
$469K
Total Drug Cost
257
Medicare Beneficiaries

Prescribing Breakdown

30-Day Fills
1,275
Total Day Supply
35,260
Brand vs Generic
15% brand / 85% generic
Brand Drug Cost
$432K
Generic Drug Cost
$38K

Patient Demographics

Average Patient Age
73.8 years
Avg HCC Risk Score
1.10
Gender Split
60% female / 40% male
Age Distribution
<65: 13, 65-74: 133, 75-84: 90, 85+: 21

Top Prescribed Drugs (Medicare Part D)

Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.

What GREGORY HARMON, M.D. prescribes most

Top Medicare Part D drugs by claim count, 2023

claims
Source CMS Medicare Part D Prescriber Public Use File As of 2023
Drug Claims
Omeprazole
148
Famotidine
96
Pantoprazole Sodium
86
Peg 3350-Electrolyte
Sodium Chloride/Nahco3/Kcl/Peg
48
Ondansetron Hcl
23
Linzess
Linaclotide
21
Humira(Cf) Pen
Adalimumab
20
Mesalamine
16
Sucralfate
12
Sod Sulf-Potass Sulf-Mag Sulf
"Sodium
N/A

* Counts below 11 are suppressed by CMS for patient privacy. Generic names shown where available from CMS Part D data.

Gastroenterology Physician Overview

How GREGORY HARMON, M.D. fits within the Gastroenterology Physician landscape nationally.

16,567
Gastroenterology Physician Providers in US
54
States with Gastroenterology Physician
833
Avg Claims per Provider

GREGORY HARMON, M.D.'s 615 claims are below the specialty average of 833.

Nearby Gastroenterology Physician Providers in California

Other clinicians with the same primary specialty enrolled in California, drawn from the same CMS NPPES roster as HARMON.

Compare Gastroenterology Physician nationally: see state-by-state distribution →

Frequently Asked Questions

What is GREGORY HARMON, M.D.'s specialty?
GREGORY HARMON, M.D. specializes in Gastroenterology Physician and practices in HARBOR CITY, California. Credentials: M.D..
How much does GREGORY HARMON, M.D. prescribe under Medicare Part D?
In 2023, GREGORY HARMON, M.D. wrote 615 Medicare Part D claims totaling $469K in drug costs for 257 beneficiaries.
Where is GREGORY HARMON, M.D. located?
GREGORY HARMON, M.D. is located at 25825 VERMONT AVE, HARBOR CITY, CA, 90710. Phone: (310) 325-5111.
What is GREGORY HARMON, M.D.'s NPI number?
GREGORY HARMON, M.D.'s National Provider Identifier (NPI) is 1346347028, issued on 09/17/2006.
Does GREGORY HARMON, M.D. prescribe more brand-name or generic drugs?
GREGORY HARMON, M.D.'s prescribing is 15% brand-name and 85% generic drugs by claim count, with $432K in brand drug costs.
How many Gastroenterology Physician providers are there in the US?
There are 16,567 Gastroenterology Physician providers across 54 states in the US. The average Gastroenterology Physician provider writes 833 Medicare Part D claims per year.
What drugs does GREGORY HARMON, M.D. prescribe most often?
Based on 2023 Medicare Part D data, GREGORY HARMON, M.D.'s most frequently prescribed drugs include Omeprazole, Famotidine, Pantoprazole Sodium. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does GREGORY HARMON, M.D. accept Medicare?
GREGORY HARMON, M.D. appears in CMS Medicare data with 615 Part D claims and 257 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify GREGORY HARMON, M.D.'s credentials?
GREGORY HARMON, M.D.'s NPI is 1346347028 with credentials M.D.. You can verify this through the NPPES NPI Registry, check state medical board records, and confirm board certification through the ABMS or AOA.

Data Sources

Provider Directory
CMS National Plan and Provider Enumeration System (NPPES), download.cms.gov/nppes, updated monthly. Contains NPI, specialty, credentials, and practice location.
Specialty Classification
NUCC Health Care Provider Taxonomy (nucc.org), the industry standard for classifying provider specialties in Medicare and Medicaid billing.
Prescribing Data
CMS Medicare Part D Prescriber Public Use File (2023). Includes claims, drug costs, beneficiaries, and opioid prescribing rates.
Limitations
Provider data is self-reported to CMS. Prescribing data reflects Medicare Part D only and does not include commercial insurance, Medicaid, or cash prescriptions. Claims below 11 beneficiaries are suppressed by CMS for privacy.

See our complete data methodology for details on how we collect and process government data.

Data as of April 2026 (NPPES) / 2023 (Medicare Part D). Source: Centers for Medicare & Medicaid Services (CMS).

Disclaimer: Data from CMS NPPES and Medicare Part D. PlainDoctor does not rate or rank providers. Provider information is self-reported and may not be current. Always verify information directly with the provider. About · Methodology