Two medicines, side by side
Clonidine vs diltiazem
Clonidine and diltiazem are both labeled for high blood pressure. Drugs@FDA records approvals of clonidine since 1974 and of diltiazem since 1982. Pharmacies paid $0.0241 per clonidine HCl 0.1 mg tablet and $0.144 per diltiazem 24h ER(cd) 120 mg capsule (NADAC, October 7, 2026); the strengths differ, so the two prices are not like for like. Clonidine's other strengths are brand-only: $1.53 per mL (Javadin 0.02 mg/mL solution). In FDA's classes, clonidine is a central alpha-2 adrenergic agonist and diltiazem a calcium channel blocker.
Check it at the source: the clonidine FDA label on DailyMed (effective March 30, 2026); the diltiazem FDA label on DailyMed (effective August 7, 2026).
Highlights of the clonidine record
Clonidine (Catapres) · label of March 30, 2026
Used for
From the label: indicationsClonidine hydrochloride tablets are indicated in the treatment of hypertension. Clonidine hydrochloride tablets may be employed alone or concomitantly with other antihypertensive agents.
On the market
- Earliest approval on file
- September 3, 1974
- Generic labelers
- 43 labelers
- Pharmacy cost
- $0.0241 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 16
Highlights of the diltiazem record
Diltiazem (Cardizem) · label of August 7, 2026
Used for
From the label: indicationsHypertension Tiazac is indicated for the treatment of hypertension. It may be used alone or in combination with other antihypertensive medications. Chronic Stable Angina Tiazac is indicated for the treatment of chronic stable angina.
On the market
- Earliest approval on file
- November 5, 1982
- Generic labelers
- 50 labelers
- Pharmacy cost
- $0.144 per capsule
Supply and safety
- Shortage
- A presentation being discontinued
- Recalls
- 29
Source: FDA drug labels via openFDA (Clonidine label of March 30, 2026, Diltiazem label of August 7, 2026); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do clonidine and diltiazem differ on the record?
In FDA's classes, clonidine is a central alpha-2 adrenergic agonist and diltiazem a calcium channel blocker.
Half-life, in each label's words: Clonidine, “Following intravenous administration, clonidine displays biphasic disposition with a distribution half-life of about 20 …”; Diltiazem, “The plasma elimination half-life of diltiazem is approximately 3.0 to 4.5 hours.”
Generics: clonidine since 1986; diltiazem since 1992 (Drugs@FDA).
| Clonidine | Diltiazem | |
|---|---|---|
| Labeled for | High blood pressure, ADHD, Pain | High blood pressure, Angina, Atrial fibrillation |
| Pharmacologic class | Central alpha-2 Adrenergic Agonist | Calcium Channel Blocker |
| How it works (label) | n/a | Mechanisms of Action Hypertension: Diltiazem produces its antihypertensive effect primarily by relaxation of vascular smooth muscle and the resultant decrease in peripheral vascular resistance. |
| Half-life (label) | Following intravenous administration, clonidine displays biphasic disposition with a distribution half-life of about 20 minutes and an elimination half-life ranging from 12 to 16 hours. | The plasma elimination half-life of diltiazem is approximately 3.0 to 4.5 hours. |
| Earliest approval on file (Drugs@FDA) | September 3, 1974 | November 5, 1982 |
| First generic approved | July 1, 1986 | November 5, 1992 |
| Generic labelers (NDC) | 43 labelers | 50 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.0241 per tablet (Clonidine HCl 0.1 mg tablet) | $0.144 per capsule (Diltiazem 24h ER(cd) 120 mg capsule) |
| 12-month price change | -3% | -4% |
| Boxed warning | No | No |
| Shortage now | No current entry | A presentation being discontinued |
| Recalls recorded | 16 | 29 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 57,116 | 34,213 |
| DEA schedule | none | none |
Source: Drugs@FDA, FDA NDC Directory, CMS NADAC of October 7, 2026, FDA shortages and recalls, FAERS via openFDA (FDA files October 8, 2026)
Do their labels mention each other?
Clonidine label, drug interactionsSinus bradycardia resulting in hospitalization and pacemaker insertion has been reported in association with the use of clonidine concomitantly with diltiazem or verapamil.
Diltiazem label, drug interactionsSinus bradycardia resulting in hospitalization and pacemaker insertion has been reported in association with the use of clonidine concurrently with diltiazem.
Source: FDA drug labels via openFDA
What next?
- Alternatives to clonidine
- every medicine labeled for the same conditions