Claus Fimmel, MD
Gastroenterology · Northbrook, ILNPI 1568417780
Payments from drug & device makers
Across 44 payments — averaging $830.09 each. Meals, travel, consulting and speaking fees, gifts and royalties reported by drug and device makers.
- Gilead$34K
- Intercept Pharmaceuticals, Inc.$2K
- Madrigal Pharmaceuticals$456
- Ardelyx, Inc.$49
- Takeda Pharmaceuticals U.S.A., Inc.$47
- Mirum Pharmaceuticals, Inc.$45
- plus $102 from 5 others
Across 11 payments — averaging $145.93 each. Payments tied to a research study. These frequently flow through the physician to a hospital or research institution rather than to the physician personally.
- Gilead$2K
What the payments were for
- Speaking & faculty fees$57620%
- Travel & lodging$1,22642%
- Food & beverage$1,12538%
General payments by program year
Who reported the general payments
Companies are grouped under their corporate parent — a single manufacturer often files under several CMS reporting entities. Research and ownership payments are counted separately and are not in this table.
| Company | Payments | Total |
|---|---|---|
| Gilead | 13 | $33,856 |
| Intercept Pharmaceuticals, Inc. | 14 | $1,970 |
| Madrigal Pharmaceuticals | 6 | $456 |
| Ardelyx, Inc. | 2 | $49 |
| Takeda Pharmaceuticals U.S.A., Inc. | 2 | $47 |
| Mirum Pharmaceuticals, Inc. | 2 | $45 |
| Olympus America Inc. | 1 | $27 |
| Ipsen Biopharmaceuticals, Inc | 1 | $26 |
| Lilly USA, LLC | 1 | $21 |
| Braintree Laboratories, Inc. | 1 | $16 |
| Echosens North America, Inc. | 1 | $12 |
What the payments were tied to
Products named in the reported payments. Only payments of $100 or more are attributed here — the typical reported payment nationally is a meal worth about $16, and listing those product-by-product would be noise.
- REZDIFFRA$348
How this compares
$36,524 in reported general payments places this provider in the 85th percentile of 787 gastroenterology providers in Illinois.
Medicare billing
What this is not: this is the amount Original Medicare Part B allowed for services this provider billed in 2024. It is not their income. It excludes Medicare Advantage — now more than half of all Medicare enrollment — along with Medicaid and all commercial insurance, and it is gross practice revenue before staff, rent, supplies and malpractice premiums. CMS also suppresses any figure covering ten or fewer patients, so low-volume providers appear smaller than they are.
Most prescribed under Part D
| Drug | Claims | Cost to plans & patients |
|---|---|---|
| Ursodiol | 44 | $6,424 |
| Gavilyte-CPeg3350/Sod Sulf,bicarb,cl/Kcl | 46 | $841 |
| Azathioprine | 21 | $652 |
| Spironolactone | 14 | $218 |
| Furosemide | 20 | $79 |
| Prednisone | 13 | $41 |
Paid to pharmacies, not to this prescriber.
Other gastroenterology in Northbrook
- Jeffrey NathansonNorthbrook$328K
- Kamran AyubOak Lawn$4.3M
- David RubinChicago$3.6M
- Jonathan RosenbergGurnee$3.1M
- Stephen HanauerChicago$2.9M
- Parambir DulaiChicago$2.2M
- Charles BerkelhammerOak Lawn$1.9M
- Ikuo HiranoChicago$1.8M
- Manish BhuvaLake Barrington$1.7M
- Steven FlammChicago$1.6M
Where these figures come from
- Payments: CMS Open Payments, program years 2019–2025 (publication P06302026_06032026).
- Billing: Medicare Physician & Other Practitioners, data year 2024. Original Medicare Part B only.
- Identity: NPPES NPI Registry, July 2026.