What the FDA labels say about taking them together
Alosetron and primaquine
Primaquine's FDA label of February 11, 2026 names alosetron in its drug interactions section; the alosetron label PlainMeds reads does not name primaquine. The primaquine label: “Effects of Primaquine on the Pharmacokinetics of Other Drugs CYP1A2 Substrates Published clinical and non-clinical reports indicate primaquine inhibits CYP1A2 enzyme activity and thus may lead to increased exposure of …”
Check it at the source: the alosetron FDA label on DailyMed (effective March 23, 2026, Legacy Pharma USA Inc.); the primaquine FDA label on DailyMed (effective February 11, 2026, Sanofi-Aventis U.S. LLC).
What does the alosetron label say about primaquine?
Alosetron's label (effective March 23, 2026) does not name primaquine in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (LOTRONEX), Legacy Pharma USA Inc., effective March 23, 2026 (SPL set c216e967-436f-475a-8e6a-2ad11adc63af), via openFDA; the full label on DailyMed
What does the primaquine label say about alosetron?
Primaquine label, drug interactionsEffects of Primaquine on the Pharmacokinetics of Other Drugs CYP1A2 Substrates Published clinical and non-clinical reports indicate primaquine inhibits CYP1A2 enzyme activity and thus may lead to increased exposure of CYP1A2 substrate drugs (e.g., duloxetine, alosetron, theophylline and tizanidine) when co-administered with Primaquine phosphate Tablets.
Source: FDA drug label (Primaquine Phosphate), Sanofi-Aventis U.S. LLC, effective February 11, 2026 (SPL set 1bfbf4ae-81b8-4160-a00d-6322aadd4b59), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Alosetron | Primaquine | |
|---|---|---|
| Labeled for | n/a | n/a |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | $2.02 per tablet 0.5 mg tablet | n/a |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once