RACHEL LYNN DUNCAN MD
Prescription History 1639601628
Internal Medicine in Saint Louis, MO
What does Dr. Duncan prescribe?
In 2024, Dr. Duncan wrote 592 Medicare prescriptions for 26 medications. The most prescribed was Atorvastatin Calcium, with 81 prescriptions for 38 patients.
Medicare Part D only. These are prescriptions filled by people with Medicare drug coverage in 2024, from the CMS data released in 2026, the most recent year available. CMS does not publish medications with fewer than 11 prescriptions, so this is not a full list of what Dr. Duncan prescribes.
Medications 26 medications
Prescriptions filled under Medicare Part D in 2024. Select a medication to see what it is used for and how it compares with other Missouri prescribers.
What it is used for
Atorvastatin is used along with a proper diet to help lower "bad" cholesterol and fats (such as LDL, triglycerides) and raise "good" cholesterol (HDL) in the blood.
Compared with Missouri prescribers
Dr. Duncan wrote 81 prescriptions for Atorvastatin Calcium, about 36% as often as the typical Missouri prescriber of it (225). Medicare paid $8.17 per fill, versus $8.36 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
Amlodipine is used with or without other medications to treat high blood pressure.
Compared with Missouri prescribers
Dr. Duncan wrote 50 prescriptions for Amlodipine Besylate, about 30% as often as the typical Missouri prescriber of it (164). Medicare paid $2.54 per fill, versus $5.31 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
Lisinopril is used to treat high blood pressure.
Compared with Missouri prescribers
Dr. Duncan wrote 46 prescriptions for Lisinopril, about 31% as often as the typical Missouri prescriber of it (151). Medicare paid $4.82 per fill, versus $5.80 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
Levothyroxine is used to treat an underactive thyroid (hypothyroidism).
Compared with Missouri prescribers
Dr. Duncan wrote 44 prescriptions for Levothyroxine Sodium, about 23% as often as the typical Missouri prescriber of it (194). Medicare paid $9.99 per fill, versus $8.86 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
See also Warning section.
Compared with Missouri prescribers
Dr. Duncan wrote 33 prescriptions for Tramadol Hcl, about 35% as often as the typical Missouri prescriber of it (93). Medicare paid $3.49 per fill, versus $7.94 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
Metformin is used with a proper diet and exercise program and possibly with other medications to control high blood sugar.
Compared with Missouri prescribers
Dr. Duncan wrote 29 prescriptions for Metformin Hcl Er, about half as often as the typical Missouri prescriber of it (67). Medicare paid $11.04 per fill, versus $8.28 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
Alprazolam is used to treat anxiety and panic disorders.
Compared with Missouri prescribers
Dr. Duncan wrote 25 prescriptions for Alprazolam, about 22% as often as the typical Missouri prescriber of it (112). Medicare paid $1.80 per fill, versus $4.98 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
This medication is used to treat high blood pressure.
Compared with Missouri prescribers
Dr. Duncan wrote 20 prescriptions for Hydrochlorothiazide, about 24% as often as the typical Missouri prescriber of it (85). Medicare paid $4.18 per fill, versus $3.84 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
Meloxicam is used to treat arthritis.
Compared with Missouri prescribers
Dr. Duncan wrote 20 prescriptions for Meloxicam, about 27% as often as the typical Missouri prescriber of it (74). Medicare paid $3.80 per fill, versus $3.88 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
This medication is a beta-blocker used to treat chest pain (angina), heart failure, and high blood pressure.
Compared with Missouri prescribers
Dr. Duncan wrote 19 prescriptions for Metoprolol Succinate, about 15% as often as the typical Missouri prescriber of it (124). Medicare paid $9.38 per fill, versus $11.38 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
Gabapentin is used with other medications to prevent and control seizures.
Compared with Missouri prescribers
Dr. Duncan wrote 18 prescriptions for Gabapentin, about 16% as often as the typical Missouri prescriber of it (115). Medicare paid $10.05 per fill, versus $15.91 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
This combination medication is used to relieve moderate to severe pain.
Compared with Missouri prescribers
Dr. Duncan wrote 18 prescriptions for Hydrocodone-Acetaminophen, about 17% as often as the typical Missouri prescriber of it (109). Medicare paid $29.85 per fill, versus $20.32 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
This medication is used to treat depression.
Compared with Missouri prescribers
Dr. Duncan wrote 18 prescriptions for Trazodone Hcl, about 19% as often as the typical Missouri prescriber of it (93). Medicare paid $4.96 per fill, versus $7.90 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
This medication is used to treat certain mental/mood disorders (such as depression, panic attacks, obsessive compulsive disorder, post-traumatic stress disorder, social anxiety disorder).
Compared with Missouri prescribers
Dr. Duncan wrote 16 prescriptions for Sertraline Hcl, about 19% as often as the typical Missouri prescriber of it (82). Medicare paid $4.96 per fill, versus $7.86 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
Zolpidem is used for a short time to treat a certain sleep problem (insomnia) in adults.
Compared with Missouri prescribers
Dr. Duncan wrote 16 prescriptions for Zolpidem Tartrate, about 27% as often as the typical Missouri prescriber of it (60). Medicare paid $14.29 per fill, versus $7.06 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
Rosuvastatin is used along with a proper diet to help lower "bad" cholesterol and fats (such as LDL, triglycerides) and raise "good" cholesterol (HDL) in the blood.
Compared with Missouri prescribers
Dr. Duncan wrote 15 prescriptions for Rosuvastatin Calcium, about 12% as often as the typical Missouri prescriber of it (127). Medicare paid $1.75 per fill, versus $10.73 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
Losartan is used to treat high blood pressure (hypertension) and to help protect the kidneys from damage due to diabetes.
Compared with Missouri prescribers
Dr. Duncan wrote 14 prescriptions for Losartan Potassium, about 11% as often as the typical Missouri prescriber of it (128). Medicare paid $3.92 per fill, versus $7.83 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
Metformin is used with a proper diet and exercise program and possibly with other medications to control high blood sugar.
Compared with Missouri prescribers
Dr. Duncan wrote 14 prescriptions for Metformin Hcl, about 13% as often as the typical Missouri prescriber of it (105). Medicare paid $5.75 per fill, versus $6.52 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
This is a long-acting form of oxybutynin that is used to treat overactive bladder and urinary conditions.
Compared with Missouri prescribers
Dr. Duncan wrote 13 prescriptions for Oxybutynin Chloride Er, about 35% as often as the typical Missouri prescriber of it (37). Medicare paid $21.43 per fill, versus $19.96 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
Valacyclovir is used to treat infections caused by certain types of viruses.
Compared with Missouri prescribers
Dr. Duncan wrote 13 prescriptions for Valacyclovir, about half as often as the typical Missouri prescriber of it (24). Medicare paid $37.49 per fill, versus $36.82 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
Albuterol (also known as salbutamol) is used to prevent and treat wheezing and shortness of breath caused by breathing problems (such as asthma, chronic obstructive pulmonary disease).
Compared with Missouri prescribers
Dr. Duncan wrote 12 prescriptions for Albuterol Sulfate Hfa, about 15% as often as the typical Missouri prescriber of it (81). Medicare paid $27.67 per fill, versus $25.65 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
This medication is used to treat certain mental/mood disorders (such as depression, panic attacks, obsessive compulsive disorder).
Compared with Missouri prescribers
Dr. Duncan wrote 12 prescriptions for Fluoxetine Hcl, about 23% as often as the typical Missouri prescriber of it (52). Medicare paid $12.67 per fill, versus $9.54 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
This medication is used to treat anxiety.
Compared with Missouri prescribers
Dr. Duncan wrote 12 prescriptions for Lorazepam, about 20% as often as the typical Missouri prescriber of it (61). Medicare paid $2.39 per fill, versus $6.67 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
This medication is a mineral supplement used to treat or prevent low amounts of potassium in the blood.
Compared with Missouri prescribers
Dr. Duncan wrote 12 prescriptions for Potassium Chloride, about 13% as often as the typical Missouri prescriber of it (90). Medicare paid $19.16 per fill, versus $17.91 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
Pantoprazole is used to treat certain stomach and esophagus problems (such as acid reflux).
Compared with Missouri prescribers
Dr. Duncan wrote 11 prescriptions for Pantoprazole Sodium, about 11% as often as the typical Missouri prescriber of it (105). Medicare paid $9.47 per fill, versus $10.99 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
What it is used for
Simvastatin is used along with a proper diet to help lower "bad" cholesterol and fats (such as LDL, triglycerides) and raise "good" cholesterol (HDL) in the blood.
Compared with Missouri prescribers
Dr. Duncan wrote 11 prescriptions for Simvastatin, about 14% as often as the typical Missouri prescriber of it (78). Medicare paid $4.43 per fill, versus $6.73 statewide.
Volume reflects how many Medicare patients a practice sees as well as prescribing habits. It is not a measure of quality.
Questions about Dr. Duncan’s prescriptions
What does Dr. Duncan prescribe most?
In 2024 Medicare Part D data, Dr. Duncan's most prescribed medications were Atorvastatin Calcium (81), Amlodipine Besylate (50) and Lisinopril (46).
How does Dr. Duncan's prescribing compare with other Missouri prescribers?
Of the 26 medications with a state comparison, Dr. Duncan prescribes 26 less often than the typical Missouri prescriber. Volume reflects practice size as well as prescribing habits.
Does this list show every medication Dr. Duncan prescribes?
No. It covers prescriptions filled by people with Medicare Part D drug coverage in 2024, and CMS leaves out any medication with fewer than 11 prescriptions.
About this data
This page shows one provider’s slice of public Medicare files. NPI Profile does not receive prescriptions or patient records.
| Source | What it provides here | Data year |
|---|---|---|
| CMS Medicare Part D Prescribers by Provider and Drug | Each medication, prescriptions, patients, 30-day fills, days of medication and cost. State comparisons average the Missouri prescribers of the same medication and form, where at least five wrote it. | 2024 (released 2026, the most recent available) |
| CMS Medicare Part D Drug Spending Dashboard | What each medication is used for. | 2024 |
- Only prescriptions filled by people with Medicare Part D drug coverage are counted. Private insurance, Medicaid and cash purchases are not.
- CMS leaves out medications with fewer than 11 prescriptions and hides patient counts under 11.
- Cost per fill is what the plan and the patient paid the pharmacy together, not what you pay at the counter.
- Medication descriptions are summaries from CMS. They are not medical advice; ask a health care professional about any medication.
