Efficacy of Gabapentin for Post-Covid-19 Olfactory Dysfunction (GRACE)

The Washington University

Status and phase: Completed; Phase 2

Conditions: COVID-19; Anosmia; Hyposmia; Parosmia; Olfactory Disorder

Treatments: Drug: Gabapentin gelatin capsules 300mg; Drug: Placebo

Study type: Interventional

Funder types: Other

Identifiers

NCT05184192

202110011

Details and patient eligibility

About

This study will investigate the efficacy of oral gabapentin in olfactory improvement following Covid-19- associated olfactory dysfunction. This is a randomized, double-blinded, placebo-controlled trial.

Full description

The drug will be given over a maximum 14 weeks with up to four weeks titrating up, eight weeks maintaining highest tolerable dose, and up to two weeks tapering down. Change in olfactory function from baseline to completion of 8-week fixed-dose period will be compared between the two study groups. Follow-up assessments will be conducted for both groups 4 weeks after completion of taper down.

Enrollment: 68 patients

Sex: All

Ages: 18 to 65 years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• Men and women between the ages of 18 and 65 years
• Residing within the states of Missouri or Illinois
• Clinically diagnosed or subjective olfactory dysfunction (anosmia, hyposmia, or parosmia) of 3 months duration or longer diagnosed within 2 weeks of Covid-19 infection
• UPSIT score consistent with diminished olfactory function (score ≤ 33 in men and ≤ 34 in women).
• Willing to respond daily to study surveys, preferably through smartphone with unlimited texting plan
• In possession of ALL 7 household items: soap, burnt candle, peanut butter, herb, garlic, lemon, and coffee

Exclusion criteria

• Clinically diagnosed olfactory dysfunction secondary to genetic abnormalities or congenital dysfunction, trauma, non-Covid-19 viral infection, nasal polyps, neurodegenerative disorders
• Current use of: azelastine, bromperidol, orophenadrine, oxomemazine, kratom, paraldehyde, or thalidomide
• History of addiction to alcohol, cocaine, or opioids
• Impaired renal function, myasthenia gravis, or myoclonus
• Severe allergy to peanuts
• Pregnancy or attempting pregnancy during study participation
• Inability to participate in virtual trial due to lack of access to the internet or unlimited text messaging; inability to comprehend or use English language
• Availability less than 6 months from time of enrollment
• Residency in states other than Missouri or Illinois.

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Triple Blind

---

68 participants in 2 patient groups, including a placebo group

Gabapentin

Experimental group

Description:

This arm will be given the active treatment, oral Letco (gabapentin) gelatin capsules of 300mg each. Up to the first four weeks will be a titration period (week 1 300mg TID, week 2 600mg TID, week 3 900mg TID, week 4 1,200mg TID) as tolerated. If intolerable adverse reactions occur, the dosage will be decreased to prior tolerable dose (e.g., if 900mg TID is intolerable, dose will be decreased to 600mg TID). The following eight weeks will be fixed dose, the highest tolerable dose from the titration period. Up to two weeks will be a taper down tailored to the maximum dose the participant reached during the titration and fixed periods. A maximum 14 weeks will mark the end of active treatment. Follow-up assessments will be conducted 4 weeks after completion of the taper-down period.

Treatment:

Drug: Gabapentin gelatin capsules 300mg

Placebo

Placebo Comparator group

Description:

Placebo gelatin capsules that look, smell, and taste like gabapentin capsules will be given to the placebo arm. To preserve double-blinding of the study, subjects will receive one capsule TID the first week, the second week two capsules TID, the third week three capsules TID, and fourth week four capsules TID as tolerated. If intolerable, the dose will be decreased to prior tolerable dose. The next eight weeks will be a fixed amount of placebo based on the highest tolerable amount from the titration period. Subjects will then taper-down placebo to imitate the gabapentin arm for maximum two weeks based on highest dose achieved during study. 4 weeks after completion of taper-down, follow-up assessments will be conducted.

Treatment:

Drug: Placebo