Two medicines, side by side
Acyclovir vs alosetron
Acyclovir is labeled for herpes and shingles; alosetron has no indication this site maps. Their labels share no use, so they are not alternatives to each other. Drugs@FDA records approvals of acyclovir since 1982 and of alosetron since 2000. Pharmacies paid $0.0962 per acyclovir 400 mg tablet and $2.02 per alosetron HCl 0.5 mg tablet (NADAC, October 7, 2026); the strengths differ, so the two prices are not like for like. In FDA's classes, acyclovir is a herpes zoster virus nucleoside analog dna polymerase inhibitor and alosetron a serotonin-3 receptor antagonist.
Check it at the source: the acyclovir FDA label on DailyMed (effective July 24, 2026); the alosetron FDA label on DailyMed (effective March 23, 2026).
Highlights of the acyclovir record
Acyclovir (Zovirax) · label of July 24, 2026
Used for
From the label: indicationsHerpes Zoster Infections: Acyclovir tablets are indicated for the acute treatment of herpes zoster (shingles). Genital Herpes: Acyclovir tablets are indicated for the treatment of initial episodes and the management of recurrent episodes of genital herpes. Chickenpox: Acyclovir tablets are indicated for the treatment of chickenpox (varicella).
On the market
- Earliest approval on file
- March 29, 1982
- Generic labelers
- 66 labelers
- Pharmacy cost
- $0.0962 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 12
Highlights of the alosetron record
Alosetron (Lotronex) · label of March 23, 2026
SERIOUS GASTROINTESTINAL ADVERSE REACTIONS Infrequent but serious gastrointestinal adverse reactions have been reported with the use of LOTRONEX. These events, including ischemic colitis and serious complications of constipation, have resulted in hospitalization, and rarely, blood transfusion, surgery, and death.
Used for
From the label: indicationsLOTRONEX is indicated only for women with severe diarrhea-predominant irritable bowel syndrome (IBS) who have: chronic IBS symptoms (generally lasting 6 months or longer), had anatomic or biochemical abnormalities of the gastrointestinal tract excluded, and not responded adequately to conventional therapy. […]
On the market
- Earliest approval on file
- February 9, 2000
- Generic labelers
- 6 labelers
- Pharmacy cost
- $2.02 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 0
Source: FDA drug labels via openFDA (Acyclovir label of July 24, 2026, Alosetron label of March 23, 2026); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do acyclovir and alosetron differ on the record?
In FDA's classes, acyclovir is a herpes zoster virus nucleoside analog dna polymerase inhibitor and alosetron a serotonin-3 receptor antagonist.
Half-life, in each label's words: Acyclovir, “Mean half-life after oral doses of 300 mg/m 2 and 600 mg/m 2 in pediatric patients aged 7 months to 7 years was 2.6 …”; Alosetron, “The terminal elimination half-life of alosetron is approximately 1.5 hours (plasma clearance is approximately 600 …”
Only the alosetron label carries a boxed warning.
Generics: acyclovir since 1997; alosetron since 2015 (Drugs@FDA).
| Acyclovir | Alosetron | |
|---|---|---|
| Labeled for | Herpes and shingles | n/a |
| Pharmacologic class | Herpes Simplex Virus Nucleoside Analog DNA Polymerase Inhibitor, Herpes Zoster Virus Nucleoside Analog DNA Polymerase Inhibitor, Herpesvirus Nucleoside Analog DNA Polymerase Inhibitor | Serotonin-3 Receptor Antagonist |
| How it works (label) | n/a | Alosetron is a potent and selective 5-HT 3 receptor antagonist. 5-HT 3 receptors are ligand-gated cation channels that are extensively distributed on enteric neurons in the human gastrointestinal tract, as well as other peripheral and … |
| Half-life (label) | Mean half-life after oral doses of 300 mg/m 2 and 600 mg/m 2 in pediatric patients aged 7 months to 7 years was 2.6 hours (range 1.59 to 3.74 hours). | The terminal elimination half-life of alosetron is approximately 1.5 hours (plasma clearance is approximately 600 mL/min). |
| Earliest approval on file (Drugs@FDA) | March 29, 1982 | February 9, 2000 |
| First generic approved | April 22, 1997 | May 4, 2015 |
| Generic labelers (NDC) | 66 labelers | 6 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.0962 per tablet (Acyclovir 400 mg tablet) | $2.02 per tablet (Alosetron HCl 0.5 mg tablet) |
| 12-month price change | +5% | -15% |
| Boxed warning | No | Yes |
| Shortage now | No current entry | No current entry |
| Recalls recorded | 12 | 0 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 114,717 | 908 |
| 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)
What next?
- Alternatives to acyclovir
- every medicine labeled for the same conditions