NPI registry status
Active
2026 NPPES data Internal Medicine Physician NPI 1568478493 M.D.
Verify on CMS → Guillermo Zegarra, M.D.
Internal Medicine Physician in Bullhead City, Arizona.
This profile is drawn from the federal National Provider Identifier Registry (CMS NPPES), which lists more than 7 million U.S. healthcare providers - including 172,737 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
12K
Medicare Part D claims · 819 beneficiaries · Internal Medicine Physician avg: 3K
Generic prescribing
90%
generic claims · 9% brand-name · higher generic rates reduce patient out-of-pocket costs
Industry payments
$300.45
14 payments · CMS Open Payments (Sunshine Act)
Source: CMS Medicare Part D Prescriber Public Use File, 2023
What the federal data shows
Guillermo Zegarra, M.D. filed 12,060 Medicare Part D claims in 2023 as an Internal Medicine Physician in Bullhead City, Arizona, prescribing 90% generic.
- 12K
- Part D claims, 2023
- 90%
- 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.
Guillermo Zegarra, M.D.'s Medicare Part D volume vs every U.S. prescriber
Total Medicare Part D claims, 2023, across all CMS prescribers nationally
12,060 Top 2% higher than 98% of 1,370,886 prescribers
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)
Guillermo Zegarra, M.D. practices in an ABMS-board-eligible specialty and shows active CMS Medicare participation + 2 hospital affiliations - 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 Guillermo Zegarra, M.D.?
Quality data not reportedPrimary specialty
Internal Medicine Physician
Medicare Part D claims
12,060 344% vs specialty avg
Specialty distribution in Arizona
How Internal Medicine Physician compares to other specialties among Arizona providers
Board certification
Not published by CMS
CMS does not publish a per-provider board-certification field in NPPES. PlainDoctor does not have a reliable per-specialty certification rate to show for Internal Medicine Physician. Verify directly:
How MIPS and board certification work
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).
Guillermo Zegarra, M.D. appears in the CMS NPPES registry as an Internal Medicine Physician provider holding M.D. credentials at 2182 HIGHWAY 95, Bullhead City, AZ, 86442, with a listed phone of (928) 758-6420. NPI 1568478493 was issued on 07/31/2006.
Medicare Part D records for calendar year 2023 show 12,060 prescription claims written by this provider, covering 819 Medicare beneficiaries and totaling roughly $1.1 million in drug spend, split 9% brand-name and 90% generic by claim count, with an opioid prescribing rate of 4.1%.
Internal Medicine Physician is a high-volume specialty nationwide, with 172,737 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
Provider Details
| NPI | 1568478493 |
|---|---|
| Specialty | Internal Medicine Physician |
| Credentials | M.D. |
| Gender | Male |
| NPI Issued | 07/31/2006 |
Hospital and facility affiliations
Facilities where Guillermo Zegarra, 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.
Aban Care Clinic LLC
Bullhead City, AZ
Colorado River Primary Care Inc
Fort Mohave, AZ
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 Guillermo Zegarra, M.D.. Source: openpaymentsdata.cms.gov.
Total received
$300
Largest payer
Astellas Pharma US 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.
Brand vs generic prescribing mix · Generic-heavy
Guillermo Zegarra, M.D. - brand share 9.0%
Internal Medicine Physician average
9% brand-name claims vs 90% generic, on 12,060 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.
12,060
Total Claims
$1.1M
Total Drug Cost
819
Medicare Beneficiaries
Prescribing Breakdown
- 30-Day Fills
- 23,891
- Total Day Supply
- 675,818
- Brand vs Generic
- 9% brand / 90% generic
- Brand Drug Cost
- $862K
- Generic Drug Cost
- $193K
- Opioid Claims
- 491 (4.1% rate)
- Antibiotic Claims
- 1,265
Patient Demographics
- Average Patient Age
- 71.2 years
- Avg HCC Risk Score
- 1.50
- Gender Split
- 54% female / 46% male
- Age Distribution
- <65: 112, 65-74: 434, 75-84: 214, 85+: 59
Top Prescribed Drugs (Medicare Part D)
Top drugs by claim count for calendar year 2023. Based on Medicare Part D data only.
What Guillermo Zegarra, M.D. prescribes most
Top Medicare Part D drugs by claim count, 2023
- Ibuprofen
Ibuprofen
502 claims
- Lisinopril
Lisinopril
445 claims
- Metoprolol Tartrate
Metoprolol Tartrate
444 claims
- Metformin Hcl
Metformin Hcl
417 claims
- Levothyroxine Sodium
Levothyroxine Sodium
408 claims
- Atorvastatin Calcium
Atorvastatin Calcium
395 claims
- Amlodipine Besylate
Amlodipine Besylate
387 claims
- Amoxicillin-Clavul…
Amoxicillin-Clavulanate Potass
363 claims
| Drug | Claims |
|---|---|
| Ibuprofen | 502 |
| Lisinopril | 445 |
| Metoprolol Tartrate | 444 |
| Metformin Hcl | 417 |
| Levothyroxine Sodium | 408 |
| Atorvastatin Calcium | 395 |
| Amlodipine Besylate | 387 |
| Amoxicillin-Clavulanate Potass Amoxicillin/Potassium Clav | 363 |
| Gabapentin | 287 |
| Omeprazole | 271 |
* 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 Guillermo Zegarra, M.D. fits within the Internal Medicine Physician landscape nationally.
172,737
Internal Medicine Physician Providers in US
56
States with Internal Medicine Physician
2,716
Avg Claims per Provider
Guillermo Zegarra, M.D.'s 12,060 claims are above the specialty average of 2,716.
Nearby Internal Medicine Physician Providers in Arizona
Other clinicians with the same primary specialty enrolled in Arizona, drawn from the same CMS NPPES roster as Zegarra.
Dr. Daniel Aaronson
MD
Tucson, AZ
Dr. Jaber Abawi
MD
Payson, AZ
Dr. Demsas Abay
MD
Peoria, AZ
Dr. Firas Abbas
M.D. M.P.H.
Mesa, AZ
Dr. Hassan Abbas
D.O.
Mesa, AZ
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 Arizona 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.
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Frequently Asked Questions
What is Guillermo Zegarra, M.D.'s specialty? ▼
Guillermo Zegarra, M.D. specializes in Internal Medicine Physician and practices in Bullhead City, Arizona. Credentials: M.D..
How much does Guillermo Zegarra, M.D. prescribe under Medicare Part D? ▼
In 2023, Guillermo Zegarra, M.D. wrote 12,060 Medicare Part D claims totaling $1.1M in drug costs for 819 beneficiaries.
Where is Guillermo Zegarra, M.D. located? ▼
Guillermo Zegarra, M.D. is located at 2182 HIGHWAY 95, Bullhead City, AZ, 86442. Phone: (928) 758-6420.
What is Guillermo Zegarra, M.D.'s NPI number? ▼
Guillermo Zegarra, M.D.'s National Provider Identifier (NPI) is 1568478493, issued on 07/31/2006.
Does Guillermo Zegarra, M.D. prescribe more brand-name or generic drugs? ▼
Guillermo Zegarra, M.D.'s prescribing is 9% brand-name and 90% generic drugs by claim count, with $862K in brand drug costs.
Does Guillermo Zegarra, M.D. prescribe opioids? ▼
Yes, Guillermo Zegarra, M.D. had 491 opioid claims in 2023 with an opioid prescribing rate of 4.1%.
How many Internal Medicine Physician providers are there in the US? ▼
There are 172,737 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 Guillermo Zegarra, M.D. prescribe most often? ▼
Based on 2023 Medicare Part D data, Guillermo Zegarra, M.D.'s most frequently prescribed drugs include Ibuprofen, Lisinopril, Metoprolol Tartrate. This reflects Medicare Part D prescriptions only and does not include commercial insurance or other payer types.
Does Guillermo Zegarra, M.D. accept Medicare? ▼
Guillermo Zegarra, M.D. appears in CMS Medicare data with 12,060 Part D claims and 819 Medicare beneficiaries in 2023. Contact the provider's office directly to confirm current Medicare enrollment and accepted plans.
How can I verify Guillermo Zegarra, M.D.'s credentials? ▼
Guillermo Zegarra, M.D.'s NPI is 1568478493 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
View source datasets and methodology notes
- 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
Every figure on PlainDoctor is rendered directly from the federal CMS NPPES registry, Medicare Part D, MIPS, and Open Payments records, no number is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of May 2026.