Table 1: Top 10 Therapeutic Classes Filled by Mail Order in Medicare Part D and Large Employer Plans,
by Volume of Prescriptions, 2018
Therapeutic class
Therapeutic group
Number of prescriptions filled by mail order
Number of enrollees with mail-order prescription
Among all prescriptions filled within therapeutic class, share filled by mail order
Medicare Part D
TOTAL, all classes
114,888,200
7,293,635
7.8%
  Antihyperlipidemic Drugs, NEC
Cardiovascular Agents
16,517,565
4,449,520
14.1%
  Cardiac, Beta Blockers
Cardiovascular Agents
8,923,545
2,552,120
11.6%
  Cardiac, ACE Inhibitors
Cardiovascular Agents
6,934,975
1,974,120
12.8%
  Psychotherapeutics, Antidepressants
Central Nervous System
6,534,395
1,659,345
6.9%
  Cardiac, Calcium Channel
Cardiovascular Agents
6,453,380
1,873,325
11.3%
  Cardiac Drugs, NEC
Cardiovascular Agents
6,021,195
1,717,620
13.2%
  Thyroit/Antithyroid, Thyroid/Hormones
Hormones & Synthetic Substitutes
5,803,410
1,561,605
12.4%
  Gastrointestinal Drug Misc, NEC
Gastrointestinal Drugs
5,642,420
1,700,580
9.7%
  Antidiabetic Agents, Misc
Hormones & Synthetic Substitutes
4,693,630
1,280,355
10.8%
  Misc Therapeutic Agents, NEC*
Misc Therapeutic Agents
2,984,960
741,870
11.7%
Large Employer Plans
TOTAL, all classes
58,076,511
6,552,568
9.1%
  Antihyperlipidemic Drugs, NEC
Cardiovascular Agents
6,743,934
1,807,415
20.1%
  Psychotherapeutics, Antidepressants
Central Nervous System
5,723,719
1,466,376
10.3%
  Thyroid/Antithyroid, Thyroid Hormones
Hormones & Synthetic Substitutes
3,409,575
897,768
15.9%
  Cardiac, ACE Inhibitors
Cardiovascular Agents
3,185,892
922,549
15.6%
  Cardiac, Beta Blockers
Cardiovascular Agents
2,680,792
780,268
15.5%
  Cardiac Drugs. NEC
Cardiovascular Agents
2,574,019
747,708
16.1%
  Antidiabetic Agents, Misc
Hormones & Synthetic Substitutes
2,512,233
665,014
15.0%
  Contraceptive, Oral Comb, NEC
Hormones & Synthetic Substitutes
2,411,000
683,445
10.3%
  Gastrointestinal Drugs Misc, NEC
Gastrointestinal Drugs
2,335,366
711,485
13.1%
  Cardiac, Calcium Channel
Cardiovascular Agents
2,043,871
604,578
14.5%
NOTE: NEC is not elsewhere classified. Estimates for large employer plans exclude enrollees with fewer than 7 months of coverage. *Less than 1% of prescriptions in the “Misc Therapeutic Agents, NEC” class are categorized in the “Respiratory Tract Agents” therapeutic group.
SOURCE: KFF analysis of IBM Marketscan Commercial Claims and Encounters Database, 2018, and 2018 Medicare prescription drug event claims for a 20 percent sample of Medicare beneficiaries from the CMS Chronic Conditions Data Warehouse.
Table 2: Top 10 Drug Products Filled by Mail Order in Medicare Part D and Large Employer Plans, by Volume of Prescriptions, 2018
Drug product Number of prescriptions filled by mail order Number of enrollees with mail-order prescription Among all prescriptions filled for drug product, share filled by mail order Indication Common brand names
Medicare Part D
Atorvastatin calcium 6,636,765 1,967,555 13.0% high cholesterol Lipitor
Levothyroxine sodium 5,698,630 1,548,500 12.5% hypothyroidism Levothroid, Levoxyl, Synthroid, Unithroid
Amlodipine besylate 4,581,675 1,350,760 11.2% hypertension Katerzia, Norvasc
Lisinopril 4,353,865 1,265,540 11.7% hypertension Prinivil, Zestril
Simvastatin 3,776,125 1,089,485 16.1% high cholesterol Zocor
Metformin HCL 3,696,385 1,104,535 12.2% type 2 diabetes Glucophage
Omeprazole 3,264,810 1,004,740 11.3% acid reflux, ulcers, heart burn Prilosec
Losartan potassium 3,120,395 949,995 12.6% hypertension Cozaar
Metoprolol succinate 2,992,240 880,120 12.8% hypertension, angina, heart failure Kapspargo Sprinkle, Toprol XL
Hydrochlorothiazide 2,288,360 690,805 13.4% hypertension Microzide
Large Employer Plans
Levothyroxine sodium 3,072,413 837,581 16.3% hypothyroidism Levothroid, Levoxyl, Synthroid, Unithroid
Atorvastatin calcium 2,858,703 864,833 18.9% high cholesterol Lipitor
Lisinopril 2,067,537 608,625 15.2% hypertension Prinivil, Zestril
Metformin HCL 1,762,022 544,089 15.5% type 2 diabetes Glucophage
Amlodipine besylate 1,349,224 407,717 13.6% hypertension Katerzia, Norvasc
Simvastatin 1,196,826 348,014 23.1% high cholesterol Zocor
Losartan potassium 1,117,641 348,870 15.3% hypertension Cozaar
Omeprazole 1,077,168 339,343 13.4% acid reflux, ulcers, heart burn Prilosec
Metoprolol succinate 965,373 281,249 16.2% hypertension, angina, heart failure Kapspargo Sprinkle, Toprol XL
Hydrochlorothiazide 939,555 287,646 14.6% hypertension Microzide
NOTE: Estimates for large employer plans exclude enrollees with fewer than 7 months of coverage. Includes all prescriptions for products containing the specified generic name. Does not reflect combination products that include the active ingredient. Each of the top 10 drugs are available generically. The “common brand names” field is provided as an example of branded versions, though these do not account for all of the mail-order fills for any of these top 10 drug products.
SOURCE: KFF analysis of IBM Marketscan Commercial Claims and Encounters Database, 2018, and 2018 Medicare prescription drug event claims for a 20 percent sample of Medicare beneficiaries from the CMS Chronic Conditions Data Warehouse.
Data Note Methods

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