John Mark Flack, MD, MPH
NPI 1164450987ActiveIndividual· Internal Medicine, Hypertension Specialist· Springfield, IL
Internal Medicine, Hypertension Specialist (MD, MPH) with Siu Physicians and Surgeons Inc, practicing in Springfield, Illinois. Their prescriptions cost Medicare Part D more than their services did: $107,670 for 1,350 claims, against $4,563 paid for services in 2024. Astrazeneca Pharmaceuticals LP was the largest of 4 companies reporting payments in 2025, $25,636 in all, mostly consulting fees. Lists Memorial Medical Center as a hospital affiliation.
Overview
| NPI | 1164450987 |
|---|---|
| Status | Active |
| Entity type | Individual |
| Credential | MD, MPH |
| Sole proprietor | No |
| NPI issued | Jun 29, 2006 |
| Last updated in NPPES | Oct 21, 2020 |
| Certified by provider | Oct 21, 2020 |
Specialties and licenses
| Taxonomy | Code | License | State |
|---|---|---|---|
| Internal Medicine, Hypertension Specialist Primary | 207RH0005X | 036-138254 | IL |
| Internal Medicine | 207R00000X | 036-138254 | IL |
Exclusion screening
| List | Result | Details |
|---|---|---|
| HHS-OIG LEIE · Nov 10, 2026 | No match | Checked by NPI and by name + state |
| North Carolina Medicaid · Nov 11, 2026 | No match | — |
| New York OMIG · Nov 11, 2026 | No match | — |
| Ohio Medicaid · Nov 11, 2026 | No match | — |
| Pennsylvania Medicheck · Nov 11, 2026 | No match | — |
| Washington HCA · Nov 11, 2026 | No match | — |
Official OIG search · How matching works ·Bulk check a roster
Medicare
| Enrollment (PECOS) | Enrolled Practitioner - Internal Medicine (IL) |
|---|---|
| Accepts assignment | Yes (participating) |
Medicare services in 2024
| Medicare patients | 44 |
|---|---|
| Services billed | 55 across 5 procedure codes |
| Paid by Medicare | $4,563 |
Part D prescriptions in 2024
| Prescriptions (claims) | 1,350 · 2,926 30-day fills |
|---|---|
| Patients | 171 |
| Total drug cost | $107,670 |
| Generic share | 90% of claims |
Education and affiliations
| Graduation year | 1982 |
|---|---|
| Medicare specialty | Internal Medicine |
Medical group
- Siu Physicians and Surgeons IncSpringfield, IL · 314 clinicians
Hospital affiliation
- Memorial Medical CenterSpringfield, IL
Industry payments (Open Payments)
- 2025$25,636 · 33 payments from 4 companies
- 2024$76,171 · 36 payments from 3 companies
Top paying companies in 2025
| Company | Amount | Payments |
|---|---|---|
| Astrazeneca Pharmaceuticals LP | $15,624 | 14 |
| Azurity Pharmaceuticals, Inc. | $8,416 | 8 |
| Recor Medical Inc | $1,543 | 10 |
| Idorsia Pharmaceuticals US Inc | $52.28 | 1 |
What the 2025 payments were for
- Consulting Fee$22,655 · 12 payments
- Travel and Lodging$2,155 · 10 payments
- Food and Beverage$825.63 · 11 payments
Receiving payments does not imply wrongdoing. What Open Payments covers ·original records