NPPES file of Aug 9, 2026

Margarita C. Castro-Zarraga, M.D.

Family Medicine Physician · Lowell, MA

Margarita C. Castro-Zarraga, M.D. is a family medicine physician with a practice address in Lowell, Massachusetts, and NPI 1578705679, issued on Apr 3, 2009. Check the license (Massachusetts 251722, as entered in NPPES) on the Massachusetts Board of Registration in Medicine; the Medicare figures below come from public CMS files.

Record from CMS NPPES, file of Aug 9, 2026 · Medicare files 2024 · method · Verify with CMS →

NPPES recordNPPES file of Aug 9, 2026
1578705679
Name
Margarita C. Castro-Zarraga
Credential
M.D.
Primary taxonomy
Family Medicine Physician 207Q00000X
License number
251722 MA
Self-reported in NPPES; status is on the state search
Practice location
161 Jackson St, Lowell, MA 01852
Phone
(978) 937-9700
Enumerated
Apr 3, 2009
Record last updated
Jan 3, 2024
Fax
(978) 221-6728
Medicaid ID
110028187A MA
Medicare enrollment
Enrolled (PECOS I20250312001989); accepts Medicare assignment
Entity
Type 1 · individual
Public record from CMS NPPES (open it on the CMS NPI Registry). Enrollment, assignment, school and telehealth: CMS Doctors and Clinicians file, Aug 2026. A record is not a license: verify it with the state board.
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8 nearest family medicine physician records → All 2,265 in Massachusetts → Look up another NPI →

Also registered at 161 Jackson St

A shared address usually means a shared clinic or building; it does not show who employs whom.

  1. Majed Abbas, MDFamily Medicine Physician1346827870
  2. Frank Abekah, MDStudent in an Organized Health Care Education/Training Program1346185634
  3. Rafat Al-RejjalStudent in an Organized Health Care Education/Training Program1770079402
  4. Shannon AlperClinical Social Worker1306414396
  5. Joseph Aniello, CARCAddiction (Substance Use Disorder) Counselor1871151654
  6. Muthulakshimi Arumugam, MSN, FNPFamily Medicine Physician1871277251

Verify Margarita C. Castro-Zarraga in five checks

  1. 1IdentityNPI record in CMS NPPESNPI lookupConfirmed in NPPES
  2. 2LicenseActive license and public ordersMassachusetts Board of Registration in Medicine
    Search for license 251722    Check the board
  3. 3Other statesLicenses and actions elsewhereDocInfo (FSMB)Not checked
  4. 4ExclusionsMedicare and Medicaid bansHHS-OIG exclusion listNot checked
  5. 5CertificationBoard certificationABMS AOA NCCPA AANPNot checked
Open the Massachusetts license search

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16% more Medicare Part D claims than the average family medicine physician in 2024

4,127 Medicare Part D claims for 300 beneficiaries, against an average of 3,544 among the 117,163 providers of this specialty who prescribed in Part D. Brand-name drugs were 20% of claims. 73 claims were for opioids.

  1. Margarita Castro-Zarraga4,127
  2. Specialty average3,544

Most prescribed

  1. Atorvastatin Calcium326 claims
  2. Amlodipine Besylate203 claims
  3. Albuterol Sulfate Hfa185 claims
  4. Gabapentin179 claims
  5. Lisinopril161 claims
  6. Metformin Hcl135 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.

Bills Medicare through 4 group practices

  1. Concord Medical Group OF Texas PLLCHenrietta, TX
  2. Concord Medical Group PLLCComanche, TX
  3. EM Alliance Texas PLLCAmarillo, TX
  4. Hospitalist Medicine Physicians OF Texas - Houston, PLLCPlainview, TX

Source: CMS Doctors and Clinicians National Downloadable File (the group practices a clinician bills Medicare through) (data.cms.gov).

Margarita C. Castro-Zarraga among 2,265 family medicine physician records in Massachusetts

Margarita C. Castro-Zarraga, M.D. is one of 2,265 family medicine physician records with a practice address in Massachusetts. 80% of them appear in a Medicare file (Part D prescribing, MIPS, Open Payments or Medicare group billing); this one does. Its NPI, issued in 2009, is newer than 58% of them.

  • NPI issued2009 · 58% of these records are older, 39% newer
  • In a Medicare fileYes · 80% of these records are
  • In the CMS Doctors and Clinicians fileYes · 68% of these records are
  • Graduated2005 · median 2006 among the 1,529 with a school on file
  • Record last updated2024 · 59% of these records were not updated in five years or more

Source: CMS NPPES, file of Aug 9, 2026, every record with primary taxonomy 207Q00000X and a Massachusetts practice address; Medicare files: CMS Part D Prescribers 2024, MIPS 2023, Open Payments 2024, Doctors and Clinicians (data.cms.gov).

Family Medicine Physician providers in Massachusetts

There are 2,265 family medicine physician records in Massachusetts.

All 2,265 in Massachusetts → Every provider in Lowell → Family Medicine Physician nationwide →

The 8 family medicine physician records with the nearest ZIP codes

  1. Majed Abbas, MDLowell, MA 018521346827870
  2. Muthulakshimi Arumugam, MSN, FNPLowell, MA 018521871277251
  3. Deepthi Desai, MDLowell, MA 018521144762998
  4. Jessica Fournier, MDLowell, MA 018521437719135
  5. John Grieveson, MDLowell, MA 018521326018813
  6. Maria Aurora Lim, M.D.Lowell, MA 018521821227661
  7. Cara Marshall, MDLowell, MA 018521609877927
  8. Zinabu Maxwell, MDLowell, MA 018521366616955

Common questions

What is Margarita C. Castro-Zarraga, M.D.'s NPI number?

Margarita C. Castro-Zarraga, M.D.'s National Provider Identifier (NPI) is 1578705679, issued on Apr 3, 2009. An NPI identifies a provider in billing; it is not a license.

Where is Margarita C. Castro-Zarraga, M.D. located?

The NPPES record lists a practice address at 161 Jackson St, Lowell, MA, 01852. Phone: (978) 937-9700. Providers update this record themselves, so call before visiting.

How can I verify Margarita C. Castro-Zarraga, M.D.'s license?

NPPES lists Massachusetts license number 251722, as entered by the provider. Search the Massachusetts Board of Registration in Medicine at https://findmydoctor.mass.gov/. The NPPES record confirms identity only; the state search shows license status, expiration and public orders.

How much does Margarita C. Castro-Zarraga, M.D. prescribe under Medicare Part D?

In 2024, Margarita C. Castro-Zarraga, M.D. had 4,127 Medicare Part D claims for 300 beneficiaries; the average among family medicine physician prescribers was 3,544. 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.

Written with AI tools from the named public files; every figure is computed from those files (how it is made).

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.