Zolpidem and Letermovir Injection: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Aug 8, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Zolpidem
Letermovir Injection
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
Increased zolpidem exposure
Interaction Deep Dive
Concomitant use of zolpidem and a CYP3A inhibitor may increase the exposure and pharmacodynamic effects of zolpidem. Consider using another zolpidem tartrate immediate-release product for a lower zolpidem tartrate dose (5 mg)1. In a study of concomitant use with ketoconazole (strong CYP3A inhibitor), zolpidem Cmax and AUC increased and the half-life was prolonged. Additionally, there was an increase in the pharmacodynamic effects of zolpidem 23. In another study with concomitant ritonavir, the clearance of zolpidem was reduced 7. If zolpidem and a strong CYP3A inhibitor are coadministered, consider using a lower zolpidem dose 2.
Why it happens (mechanism)
Inhibition of CYP3A-mediated metabolism of zolpidem
Literature reports
6 reports — tap to read
a) Coadministration of a single dose of zolpidem tartrate 5 mg and ketoconazole (a potent CYP3A4 inhibitor) 200 mg twice daily for 2 days increased zolpidem Cmax by 30% and the total AUC by 70% compared to zolpidem alone and prolonged the half-life of zolpidem by 30%. Additionally there was an increase in the pharmacodynamic effects of zolpidem 231.
b) The zolpidem Cmax, total AUC, and half-life were significantly increased after pretreatment with fluvoxaMINE in a pharmacokinetic trial with 20 healthy male volunteers (22 to 30 years old). Participants were given a single dose of zolpidem 5 mg (day 1), followed by 6 days of fluvoxaMINE 100 mg/day (days 2 to 7), and a second dose of zolpidem 5 mg together with fluvoxaMINE 100 mg on day 8. The mean Cmax of zolpidem was 56.4 +/- 25.6 nanograms (ng)/mL on day 1 and 67.3 +/- 25.8 ng/mL after pretreatment with fluvoxaMINE (p=0.005; 90% CI, 1.10 to 1.37), and the zolpidem AUC(0 to infinity) increased by approximately 150% from 200.9 +/- 116.8 ng x hr/mL to 512 +/- 354.6 ng x hr/mL after pretreatment (p less than 0.0001; 90% CI, 2.14 to 2.71). The half-life was 2.24 +/- 0.8 hours with zolpidem alone compared with 4.99 +/- 2.92 hours with concomitant fluvoxaMINE (p less than 0.0001). Chronic use of concomitant zolpidem and fluvoxaMINE might lead to enhanced adverse effects associated with zolpidem 4.
c) Coadministration of a single dose of zolpidem tartrate 10 mg and itraconazole 200 mg at steady-state levels in male subjects resulted in a 34% increase in zolpidem AUC(0 to infinity), but no pharmacodynamic effects of zolpidem detected on subjective drowsiness, postural sway, or psychomotor performance 231.
d) Increased plasma concentrations and pharmacodynamic effects of zolpidem when coadministered with ketoconazole were demonstrated in a randomized, double-blind, 5-way crossover study of 12 healthy volunteers. The study involved five treatment protocols: (a) zolpidem placebo plus azole placebo, (b) 5 mg zolpidem plus azole placebo, (c) zolpidem plus ketoconazole, (d) zolpidem plus itraconazole, and (e) zolpidem plus fluconazole. The mean clearance of zolpidem was decreased from 422 mL/min for the (b) treatment group to 250 mL/min for the (c) treatment group. Changes also were noted in the elimination half-life (t1/2) from 1.86 to 2.41 hours, and AUC from 254 to 424 ng/mL/hr. The ketoconazole group also demonstrated pharmacodynamic changes as expressed by EEG beta amplitude increases and impairment of DSST (digit-symbol substitution test) scores, as well as slight impairment of delayed recall. There were no significant changes in kinetics or dynamics of zolpidem in the other azole treatment groups 5.
e) In a pharmacokinetic study (n=19), concomitant administration of single-dose zolpidem 5 mg and telaprevir 750 mg every 8 hours for 10 days resulted in decreases in zolpidem AUC and Cmax. The ratio estimate for zolpidem AUC and Cmax (with telaprevir to without telaprevir) was 0.53 and 0.58 , respectively 6.
f) A study involving 6 healthy male volunteers demonstrated that coadministration of ritonavir and zolpidem did not alter pharmacodynamic effects of zolpidem. Each patient received zolpidem 5 mg and 4 scheduled doses of ritonavir 200 mg. The results included a significant reduction in zolpidem clearance to 78% of control values. The elimination half-life was prolonged from 2 to 2.4 hours, which was not significant 7.
Common questions
Can I take Zolpidem and Letermovir Injection together?
Increased zolpidem exposure Always confirm with your pharmacist or prescriber before making any change.
How serious is the Zolpidem and Letermovir Injection interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "established". Well documented — supported by controlled studies or strong clinical data.
Questions for your pharmacist
- Does my dose of Zolpidem or Letermovir Injection need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (7)
- Product Information: Zolpidem Tartrate oral capsules, zolpidem tartrate oral capsules. Almatica Pharma LLC(per FDA), Morristown, NJ, 2023. DailyMed
- Product Information: AMBIEN CR(R) oral extended-release tablets, zolpidem tartrate oral extended-release tablets. sanofi-aventis U.S. LLC (per FDA), Bridgewater, NJ, 2016. DailyMed
- Product Information: AMBIEN(R) oral tablets, zolpidem tartrate oral tablets. sanofi-aventis US LLC (per FDA), Bridgewater, NJ, 2022. DailyMed
- Vlase L, Popa A, Neag M, et al: Effect of fluvoxamine on the pharmacokinetics of zolpidem: a two-treatment period study in healthy volunteers. Clinical & Experimental Pharmacology & Physiology 2012; 39(1):9-12.
- Greenblatt DJ, von Moltke LL, Harmatz JS, et al: Kinetic and dynamic interaction study of zolpidem with ketoconazole, itraconazole, and fluconazole. Clin Pharmacol Ther 1998; 64:661-671. PubMed
- Product Information: INCIVEK(R) oral tablets, telaprevir oral tablets. Vertex Pharmaceuticals Incorporated (per FDA), Cambridge, MA, 2013.
- Greenblatt DJ, vonMoltke LL, Harmatz JS, et al: Differential Impairment of triazolam and zolpidem clearnace by ritonavir. JAIDS 2000; 24(2):129-136.
Keep reading about Zolpidem
Keep reading about Letermovir Injection
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist