2026 NPPES data Gastroenterology Physician NPI 1558399436 M.D.
Verify on CMS →

CHARLES KING, M.D.

Gastroenterology Physician in ANNAPOLIS, Maryland. 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
950
Medicare Part D claims · 146 beneficiaries · Gastroenterology Physician avg: 833
Generic prescribing
91%
generic claims · 9% brand-name · higher generic rates reduce patient out-of-pocket costs
Industry payments
$1.1K
53 payments · CMS Open Payments (Sunshine Act)

What the federal data shows

CHARLES KING, M.D. filed 950 Medicare Part D claims in 2023 as a Gastroenterology Physician in ANNAPOLIS, Maryland, prescribing 91% generic.

950
Part D claims, 2023
91%
generic prescribing
$1.1K
industry payments (Sunshine Act)

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.

CHARLES KING, M.D.'s Medicare Part D volume vs every U.S. prescriber

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

950 Top 25% higher than 75% 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%). Below this entry. 800–1,000: 40,919 prescribers (3%). This entry sits in this band. 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-eligible specialty (heuristic — not verified)

CHARLES KING, M.D. practices in an ABMS-board-eligible specialty but we don't have enough CMS-participation signals to confirm active board-certified status. Consult CertificationMatters.org (the official ABMS public lookup).

What does the federal data show about CHARLES KING, M.D.?

Quality data not reported

NPI registry status

Active

Issued 06/29/2006

NPI 1558399436

Primary specialty

Gastroenterology Physician

Mid-sized

16,567 US NPIs in this specialty

Medicare Part D claims

950 14% vs specialty avg

2023 prescription claims

Specialty avg: 833

Specialty distribution in Maryland

How Gastroenterology Physician compares to other specialties among Maryland providers

Maryland providers

Gastroenterology Physician share within Maryland

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

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).

CHARLES KING, M.D. appears in the CMS NPPES registry as a Gastroenterology Physician provider holding M.D. credentials at 621 RIDGELY AVE, ANNAPOLIS, MD, 21401, with a listed phone of (410) 224-4887. NPI 1558399436 was issued on 06/29/2006. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what KING 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 950 prescription claims written by this provider, covering 146 Medicare beneficiaries and totaling roughly $521K in drug spend, split 9% brand-name and 91% 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

621 RIDGELY AVE
ANNAPOLIS, MD 21401

Provider Details

NPI 1558399436
Specialty Gastroenterology Physician
Credentials M.D.
Gender Male
NPI Issued 06/29/2006

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 CHARLES KING, M.D.. Source: openpaymentsdata.cms.gov.

Total received

$1.1K

Largest payer

GENZYME CORPORATION

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.

Brand vs generic prescribing mix · Generic-heavy

CHARLES KING, M.D. — brand share 9.0%
Specialty average (est.)

9% brand-name claims vs 91% generic, on 950 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.

950
Total Claims
$521K
Total Drug Cost
146
Medicare Beneficiaries

Prescribing Breakdown

30-Day Fills
2,387
Total Day Supply
70,876
Brand vs Generic
9% brand / 91% generic
Brand Drug Cost
$396K
Generic Drug Cost
$125K

Patient Demographics

Average Patient Age
73.2 years
Avg HCC Risk Score
1.04
Gender Split
51% female / 49% male

Top Prescribed Drugs (Medicare Part D)

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

What CHARLES KING, 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
Famotidine
283
Pantoprazole Sodium
138
Ursodiol
93
Omeprazole
75
Mesalamine Er
Mesalamine
64
Lansoprazole
30
Sucralfate
23
Balsalazide Disodium
22
Creon
Lipase/Protease/Amylase
21
Bethanechol Chloride
14

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

Gastroenterology Physician Overview

How CHARLES KING, 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

CHARLES KING, M.D.'s 950 claims are above the specialty average of 833.

Nearby Gastroenterology Physician Providers in Maryland

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

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

Frequently Asked Questions

What is CHARLES KING, M.D.'s specialty?
CHARLES KING, M.D. specializes in Gastroenterology Physician and practices in ANNAPOLIS, Maryland. Credentials: M.D..
How much does CHARLES KING, M.D. prescribe under Medicare Part D?
In 2023, CHARLES KING, M.D. wrote 950 Medicare Part D claims totaling $521K in drug costs for 146 beneficiaries.
Where is CHARLES KING, M.D. located?
CHARLES KING, M.D. is located at 621 RIDGELY AVE, ANNAPOLIS, MD, 21401. Phone: (410) 224-4887.
What is CHARLES KING, M.D.'s NPI number?
CHARLES KING, M.D.'s National Provider Identifier (NPI) is 1558399436, issued on 06/29/2006.
Does CHARLES KING, M.D. prescribe more brand-name or generic drugs?
CHARLES KING, M.D.'s prescribing is 9% brand-name and 91% generic drugs by claim count, with $396K 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 CHARLES KING, M.D. prescribe most often?
Based on 2023 Medicare Part D data, CHARLES KING, M.D.'s most frequently prescribed drugs include Famotidine, Pantoprazole Sodium, Ursodiol. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does CHARLES KING, M.D. accept Medicare?
CHARLES KING, M.D. appears in CMS Medicare data with 950 Part D claims and 146 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify CHARLES KING, M.D.'s credentials?
CHARLES KING, M.D.'s NPI is 1558399436 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