Payment overview · 2025
General Payments
We did not find matching Open Payments records for this doctor in the selected program year.
Healthcare provider profile · identity verified
John A Hamjian, M.D.
Neurology · HYANNIS, MA · NPI 1124120613
Verified facts
What the public records show
We did not find matching Open Payments records for this doctor in 2025.
These records do not establish that a payment influenced prescribing or medical care.
Separate record types
Research & Ownership
Research Payments (direct recipient): not present in the loaded data
Associated Research Funding (for example, named PI): not present in the loaded data
Ownership / Investment: not present in the loaded data
These categories are never added into the General Payments headline. Associated research funding must not be described as money the doctor personally received unless the source record supports that conclusion.
Analysis 1 · Payment-linked products
Products named in Open Payments records
No payment-linked product analysis is available because no matching General Payment records were found for the selected year.
Public prescribing for products named in payments
There is no explicit payment-product set available for a Part D comparison.
The presence of the same drug in both datasets does not show that a payment caused or influenced a prescription.
Analysis 2 · Same-company prescribing overlap
Drugs reported in other payments from the same company that also appear in Medicare Part D
This analysis is independent from products named on this doctor’s individual payment records. A row appears only when the exact Open Payments reporting entity paid this doctor, that same reporting entity reported the drug or biological on at least 10 loaded General Payment records involving at least 2 distinct recipient NPIs, and this doctor has the same non-generic brand in public Part D data. This does not mean the company owns or manufactures the drug.
There is no payer-company set available for this comparison.
These facts do not show that a payment was for the drug, that the company owns or manufactures the drug, or that a payment caused or influenced prescribing.
Public Medicare Part D data
Provider-and-drug rows loaded for 2024
| Brand | Generic | Claims | Beneficiaries |
|---|---|---|---|
| Gabapentin | Gabapentin | 312 | 83 |
| Donepezil Hcl | Donepezil Hcl | 184 | 49 |
| Carbidopa-Levodopa | Carbidopa/Levodopa | 163 | 44 |
| Memantine Hcl | Memantine Hcl | 115 | 26 |
| Topiramate | Topiramate | 102 | 27 |
| Ropinirole Hcl | Ropinirole Hcl | 97 | 16 |
| Levetiracetam | Levetiracetam | 94 | 21 |
| Primidone | Primidone | 56 | 16 |
| Pregabalin | Pregabalin | 45 | 12 |
| Nortriptyline Hcl | Nortriptyline Hcl | 43 | 12 |
| Carbamazepine | Carbamazepine | 41 | suppressed |
| Pramipexole Dihydrochloride | Pramipexole Di-Hcl | 41 | suppressed |
| Sumatriptan Succinate | Sumatriptan Succinate | 39 | suppressed |
| Clopidogrel | Clopidogrel Bisulfate | 35 | suppressed |
| Duloxetine Hcl | Duloxetine Hcl | 34 | suppressed |
| Buspirone Hcl | Buspirone Hcl | 33 | suppressed |
| Lamotrigine | Lamotrigine | 33 | suppressed |
| Divalproex Sodium | Divalproex Sodium | 29 | suppressed |
| Divalproex Sodium Er | Divalproex Sodium | 29 | suppressed |
| Trazodone Hcl | Trazodone Hcl | 28 | suppressed |
| Phenytoin Sodium Extended | Phenytoin Sodium Extended | 27 | suppressed |
| Ondansetron Hcl | Ondansetron Hcl | 26 | suppressed |
| Sertraline Hcl | Sertraline Hcl | 26 | suppressed |
| Phenobarbital | Phenobarbital | 25 | suppressed |
| Carbidopa-Levodopa Er | Carbidopa/Levodopa | 20 | suppressed |
| Fludrocortisone Acetate | Fludrocortisone Acetate | 20 | suppressed |
| Rivastigmine | Rivastigmine | 20 | suppressed |
| Butalbital-Acetaminophen-Caffe | Butalb/Acetaminophen/Caffeine | 19 | suppressed |
| Baclofen | Baclofen | 18 | suppressed |
| Escitalopram Oxalate | Escitalopram Oxalate | 18 | suppressed |
| Pyridostigmine Bromide | Pyridostigmine Bromide | 17 | suppressed |
| Propranolol Hcl | Propranolol Hcl | 16 | suppressed |
| Dilantin | Phenytoin Sodium Extended | 15 | suppressed |
| Trihexyphenidyl Hcl | Trihexyphenidyl Hcl | 15 | suppressed |
| Ibuprofen | Ibuprofen | 14 | suppressed |
| Midodrine Hcl | Midodrine Hcl | 14 | suppressed |
| Quetiapine Fumarate | Quetiapine Fumarate | 14 | suppressed |
| Rizatriptan | Rizatriptan Benzoate | 14 | suppressed |
| Carbamazepine Er | Carbamazepine | 13 | suppressed |
| Memantine Hcl Er | Memantine Hcl | 13 | suppressed |
| Phenytoin | Phenytoin | 13 | suppressed |
| Xywav | Sodium,calcium,mag,pot Oxybate | 13 | suppressed |
| Lacosamide | Lacosamide | 12 | suppressed |
| Naproxen | Naproxen | 11 | suppressed |
Timeline
Payment and prescribing data by year
Open Payments and Medicare Part D may refer to different years. They are shown separately rather than aligned as if they describe the same period.
| Year | General Payments | Main payer | Explicit products | Company overlaps | Part D coverage |
|---|---|---|---|---|---|
| 2025 | — | — | — | — | — |
| 2024 | — | — | — | — | Complete |
Questions to ask
Questions you could discuss with your doctor
- Are there reasonable alternatives I should understand when we discuss treatment options?
- How should I interpret the industry-payment records shown here in the context of my care?
These are general questions generated from reviewed templates. They are not personalized medical advice.
Sources and limitations
How to read this page
- Payment and Medicare prescribing data can cover different years; every comparison shows both years explicitly.
- Part D does not represent a doctor’s entire practice; it excludes many patients and is subject to CMS public-release thresholds.
- Company–drug relationships must have an auditable source, a precise relationship type, and a valid evidence period. Unresolved mappings are not published.
- Generic drug claims are not attributed to a specific manufacturer without manufacturer-level evidence.
- When a source extract is incomplete, missing rows are never treated as proof of no payments or no prescriptions.
Loaded source releases
| Dataset | Year | Publication | Source |
|---|---|---|---|
| CMS Open Payments — General Payments | 2025 | 2026-06-30 | Original source |
| Medicare Part D Prescribers by Provider and Drug | 2024 | 2026-05-06 | Original source |
| NPPES Data Dissemination V2 | current / reference data | 2026-08-10 | Original source |
Full methodology · Questions & answers · Report a possible error