2026 NPPES data Internal Medicine Physician NPI 1952680282 MD
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Hernan Zamalloa Castro, MD

Internal Medicine Physician in Corpus Christi, Texas. This profile is drawn from the federal National Provider Identifier Registry (CMS NPPES), which lists more than 7 million U.S. healthcare providers — including 172,858 in Internal Medicine Physician, and covers specialty classification, practice address, and Medicare Part D prescribing data when reported. According to CMS, every field reflects the provider's official federal registration — see our methodology.

Federal data — no proprietary rating. We show these CMS records as-is — no composite score, no star rating, no editorial opinion layered on top.
Prescribing volume
412
Medicare Part D claims · 182 beneficiaries · Internal Medicine Physician avg: 3K
Generic prescribing
91%
generic claims · 9% brand-name · higher generic rates reduce patient out-of-pocket costs
Compiled from official public sources by the PlainDoctor editorial team.

What the federal data shows

Hernan Zamalloa Castro, MD filed 412 Medicare Part D claims in 2023 as a Internal Medicine Physician in Corpus Christi, Texas, prescribing 91% generic.

412
Part D claims, 2023
91%
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.

Hernan Zamalloa Castro, MD's Medicare Part D volume vs every U.S. prescriber

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

412 Top 38% higher than 62% 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%). This entry sits in this band. 600–800: 56,224 prescribers (4%). Above this entry. 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)

Hernan Zamalloa Castro, MD 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 Hernan Zamalloa Castro, MD?

Quality data not reported

NPI registry status

Active

Issued 08/04/2011

NPI 1952680282

Primary specialty

Internal Medicine Physician

High-volume

172,858 US NPIs in this specialty

Medicare Part D claims

412 85% vs specialty avg

2023 prescription claims

Specialty avg: 2,716

Specialty distribution in Texas

How Internal Medicine Physician compares to other specialties among Texas providers

Texas providers

Largest specialties in Texas (% of in-state providers)

Behavior Technician — 5.6%Behavior Technician5.6%Student in an Organized Health Care Education/Training Program — 5.1%Student in an Organized Health Care Education/Training Program5.1%Family Nurse Practitioner — 4.5%Family Nurse Practitioner4.5%Professional Counselor — 4.4%Professional Counselor4.4%Pharmacist — 4.4%Pharmacist4.4%Speech-Language Pathologist — 3.9%Speech-Language Pathologist3.9%Internal Medicine Physician — 2.6%Internal Medicine Physician2.6%
Largest specialties in Texas (% of in-state providers)

Specialty board-certification context

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

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

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

0%100%78%
Est. board-certified rate (Internal Medicine 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).

Hernan Zamalloa Castro, MD appears in the CMS NPPES registry as a Internal Medicine Physician provider holding MD credentials at 3315 S ALAMEDA ST, Corpus Christi, TX, 78411, with a listed phone of (361) 882-3198. NPI 1952680282 was issued on 08/04/2011. Because NPPES data is self-reported by the provider and refreshed monthly, the address, phone, and specialty reflect what Zamalloa Castro 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 412 prescription claims written by this provider, covering 182 Medicare beneficiaries and totaling roughly $17K in drug spend, split 9% brand-name and 91% generic by claim count, with an opioid prescribing rate of 7.8%. 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.

Internal Medicine Physician is a high-volume specialty nationwide, with 172,858 enrolled providers across 56 states and an average of 2,716 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

3315 S ALAMEDA ST
Corpus Christi, TX 78411

Provider Details

NPI 1952680282
Specialty Internal Medicine Physician
Credentials MD
Gender Male
NPI Issued 08/04/2011

Hospital and facility affiliations

Facilities where Hernan Zamalloa Castro, MD 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.

Hha Hospital Medicine OF Texas PLLC
Huntsville, TX

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

License & disciplinary context — Texas TMB 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 ~77K Texas medical licensees in 2023 — they are NOT specific to Hernan Zamalloa Castro, MD. To verify Hernan Zamalloa Castro, MD's current license status, search the TMB public license lookup directly, or check the Federation of State Medical Boards (FSMB) verification service.

344
Total board actions, Texas 2023
Across 334 cases
4.47
Actions per 1,000 licensees
Texas statewide rate
probation
Most common action type
94 cases

TMB 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 Texas disciplinary trends page. Cross-checked against FSMB U.S. Medical Regulatory Trends.

Brand vs generic prescribing mix · Generic-heavy

Hernan Zamalloa Castro, MD — brand share 9.0%
Internal Medicine Physician average

9% brand-name claims vs 91% generic, on 412 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.

412
Total Claims
$17K
Total Drug Cost
182
Medicare Beneficiaries

Prescribing Breakdown

30-Day Fills
417
Total Day Supply
8,088
Brand vs Generic
9% brand / 91% generic
Brand Drug Cost
$11K
Generic Drug Cost
$6K
Opioid Claims
32 (7.8% rate)
Antibiotic Claims
112

Patient Demographics

Average Patient Age
72.9 years
Avg HCC Risk Score
2.88
Gender Split
53% female / 47% male
Age Distribution
<65: 30, 65-74: 78, 75-84: 52, 85+: 22

Top Prescribed Drugs (Medicare Part D)

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

What Hernan Zamalloa Castro, MD 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
Amoxicillin-Clavulanate Potass
Amoxicillin/Potassium Clav
29
Cefuroxime
Cefuroxime Axetil
26
Amlodipine Besylate
24
Furosemide
24
Tramadol Hcl
23
Pantoprazole Sodium
18
Atorvastatin Calcium
14
Metoprolol Tartrate
14
Eliquis
Apixaban
12
Doxycycline Hyclate
11

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

Internal Medicine Physician Overview

How Hernan Zamalloa Castro, MD fits within the Internal Medicine Physician landscape nationally.

172,858
Internal Medicine Physician Providers in US
56
States with Internal Medicine Physician
2,716
Avg Claims per Provider

Hernan Zamalloa Castro, MD's 412 claims are below the specialty average of 2,716.

Nearby Internal Medicine Physician Providers in Texas

Other clinicians with the same primary specialty enrolled in Texas, drawn from the same CMS NPPES roster as Zamalloa Castro.

Compare Internal Medicine Physician nationally: see state-by-state distribution →

Before you book an appointment

Use this federal record as your verification checklist, not as a recommendation.

  • Confirm the NPI record is current in the official CMS registry — providers update their own NPPES details, and moves can lag. Verify this NPI
  • Check the active license and any disciplinary history with the Texas medical board — federal registration is not a license check. Credential verification guide
  • Weigh a second option: compare this provider with a nearby Internal Medicine Physician peer on Medicare volume and prescribing patterns. Compare providers

Medicare Part D and MIPS figures describe practice patterns in federal programs only — they are not quality ratings, and PlainDoctor does not rate, rank, or recommend providers.

Frequently Asked Questions

What is Hernan Zamalloa Castro, MD's specialty?
Hernan Zamalloa Castro, MD specializes in Internal Medicine Physician and practices in Corpus Christi, Texas. Credentials: MD.
How much does Hernan Zamalloa Castro, MD prescribe under Medicare Part D?
In 2023, Hernan Zamalloa Castro, MD wrote 412 Medicare Part D claims totaling $17K in drug costs for 182 beneficiaries.
Where is Hernan Zamalloa Castro, MD located?
Hernan Zamalloa Castro, MD is located at 3315 S ALAMEDA ST, Corpus Christi, TX, 78411. Phone: (361) 882-3198.
What is Hernan Zamalloa Castro, MD's NPI number?
Hernan Zamalloa Castro, MD's National Provider Identifier (NPI) is 1952680282, issued on 08/04/2011.
Does Hernan Zamalloa Castro, MD prescribe more brand-name or generic drugs?
Hernan Zamalloa Castro, MD's prescribing is 9% brand-name and 91% generic drugs by claim count, with $11K in brand drug costs.
Does Hernan Zamalloa Castro, MD prescribe opioids?
Yes, Hernan Zamalloa Castro, MD had 32 opioid claims in 2023 with an opioid prescribing rate of 7.8%.
How many Internal Medicine Physician providers are there in the US?
There are 172,858 Internal Medicine Physician providers across 56 states in the US. The average Internal Medicine Physician provider writes 2,716 Medicare Part D claims per year.
What drugs does Hernan Zamalloa Castro, MD prescribe most often?
Based on 2023 Medicare Part D data, Hernan Zamalloa Castro, MD's most frequently prescribed drugs include Amoxicillin-Clavulanate Potass, Cefuroxime, Amlodipine Besylate. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Hernan Zamalloa Castro, MD accept Medicare?
Hernan Zamalloa Castro, MD appears in CMS Medicare data with 412 Part D claims and 182 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Hernan Zamalloa Castro, MD's credentials?
Hernan Zamalloa Castro, MD's NPI is 1952680282 with credentials MD. 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

Compiled from official public sources by the PlainDoctor editorial team.