CompletedNCT05184192GRACEUpdated Mar 4, 2025Results posted

Efficacy of Gabapentin for Post-Covid-19 Olfactory Dysfunction

A Phase 2 interventional study of Gabapentin gelatin capsules 300mg and Placebo in COVID-19, Olfactory Disorder and Anosmia, sponsored by Washington University School of Medicine. Completed at 1 site in United States. Open to participants aged 18 Years to 65 Years. Per ClinicalTrials.gov, last updated 2025-03-04.

Sponsored by Washington University School of Medicine · Phase 2, Interventional, and Treatment

Phase: Phase 2
Study type: Interventional
Enrollment: 68
Allocation: Randomized
Ages: 18 Years to 65 Years
Sex: All

Study summary

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.

Read the detailed 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.

Conditions studied

COVID-19
Olfactory Disorder
Anosmia
Hyposmia
Parosmia

Browse trials for

In context

COVID-19

7,990 studies on the registry are indexed under COVID-19; 466 are open to participants now.

This study's enrollment of 68 is below the median of 102 across 4,364 interventional studies indexed under COVID-19.

Browse COVID-19 studies →

Lead sponsor

Washington University School of Medicine is the lead sponsor of 1,803 studies on the registry; 271 are open to participants now.

Of its 329 completed or terminated interventional studies of FDA-regulated products, 216 (66%) have results posted.

Browse Washington University School of Medicine studies →

Counted across the registry records on this site, refreshed daily.

Who can participate

Ages eligible: 18 Years to 65 Years
Sexes eligible: All
Accepts healthy volunteers: No

Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.

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

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.

Study design

Phase: Phase 2
Primary purpose: Treatment
Allocation: Randomized
Intervention model: Parallel assignment
Masking: Triple (Participant, Investigator, Outcomes assessor)
Enrollment: 68 participants (actual)

Study arms

Experimental
Gabapentin
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.
Drug: Gabapentin gelatin capsules 300mg
Placebo comparator
Placebo
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.
Drug: Placebo

Interventions

DrugGabapentin gelatin capsules 300mg
Gabapentin is an anti-epileptic also used for nerve pain. This study will investigate the efficacy of gabapentin for olfactory nerve recovery and improvement in post-Covid-19 olfactory dysfunction.
Also known as: Letco
DrugPlacebo
lactose monohydrate NF

What researchers measure

Primary outcomes

Clinical Global Impression of Improvement Scale (CGI-I)
The primary outcome measure was the treatment response rate following the 8-week FD phase as determined by the CGI-I. The CGI-I is a modified 7-point Likert scale of -perceived change. Response options include: (1) much better, (2) somewhat better, (3) slightly better), (4) neither better nor worse, (5) slightly worse, (6) somewhat worse, (7) much worse. The response rate was defined as the number of participants self-reporting at least "slightly better" divided by the number of participants in each treatment group. Th
Time frame: After the 8 week FD phase and four week post-tapper

Secondary outcomes

University of Pennsylvania Smell Identification Test (UPSIT)
Forty different odors are presented in this test. Scoring: Forced choice of 4 responses to identify each smell. Anosmia: score 6-18; severe microsmia: score 19-25, moderate microsmia: 26-30 in women and 26-29 in men; mild microsmia: 31-34 in women and 30-33 in men; and normosmia: score \> 34 in women and \>33 in men. The total UPSIT score can range from 0 to 40 and scores. The MCID in UPSIT score is 4. Scores are interpreted as the level of absolute smell function (i.e., normosmia, mild hyposmia, moderate hyposmia, severe hyposmia, and anosmia), using the age- and sex-related normative classification system described in the UPSIT manual (Table 1)
Time frame: Baseline, after completion of eight-week fixed-dose period, and 4 weeks after completion of taper-down period
Olfactory Dysfunction Outcomes Rating (ODOR)
The ODOR questionnaire is a validated 28-item patient-reported outcome measure which assesses the physical, functional, and emotional consequences of OD. The ODOR is a 28-item instrument with each item scored as either no difficulty or very rarely bothered (0) to complete difficulty or very frequently bothered (4) with a total instrument score range of 0 to 112 points. Higher scores indicate higher degree of dysfunction and limitation. the MCID is 15 points.
Time frame: Baseline, after completion of eight-week fixed-dose period, and 4 weeks after completion of taper-down period
NASAL-7
NASAL-7 is a simple diagnostic tool for olfactory dysfunction that is based on commonly found household items and can be used by adults who suspect olfactory dysfunction. The NASAL-7 was developed by Dr. Piccirillo and colleagues in the Clinical Outcomes Research Office. The NASAL-7, contains 7 household items with each item scored as 0 for 'Cannot Smell', 1 for 'Smells Less Strong/Different Than Normal', and 2 for 'Smells Normal', for a total possible score ranging from 0-14. The following four categories of olfactory function were defined based on NASAL-7 score: anosmia (score 0-4), severe dysfunction (score 5-7), mild dysfunction (score 8-10), and normosmia (score 11-14).
Time frame: Baseline, after completion of eight-week fixed-dose period, and 4 weeks after completion of taper-down period
CGI-Severity of Smell
CGI-Severity. The CGI-Severity scale ranges from 1 to 7, where 1 is normal function and 7 is complete anosmia. This assessment will provide subjective data on patients' baseline olfactory function prior to beginning the trial, after 8-week Fixed-Dose period, and 4 weeks after completion of Taper-Down phase
Time frame: 8-week Fixed-Dose period, and 4 weeks after completion of Taper-Down phase
CGI-S of Parosmia
Clinical Global Impression-Severity Scale for Parosmics (CGI-P). The CGI-P Scale is a global rating of parosmia and the single global rating ranges from 1-5, where 1 is No Distortion, 2 is Mild Distortion, 3 is Moderate Distortion, 4 is Mostly Distorted, and 5 is Complete Distortion. The response on the CGI-P will provide information on the patient's perceived severity of the distortion of their smell.
Time frame: 8-week Fixed-Dose period, and 4 weeks after completion of Taper-Down phase

Results

Posted Mar 4, 2025

Participant flow

Participant flow — Overall Study
Milestone	Gabapentin	Placebo
Started	34	34
Completed	26	17
Not completed	8	17
Withdrew: Lost to follow-up	4	7
Withdrew: Adverse event	1	4
Withdrew: Pi withdrawal	1	2
Withdrew: Withdrew due to adverse effect	1	0
Withdrew: Medication schedule	1	0
Withdrew: Concern for adverse effects	0	4

Outcome measures

PrimaryClinical Global Impression of Improvement Scale (CGI-I)

The primary outcome measure was the treatment response rate following the 8-week FD phase as determined by the CGI-I. The CGI-I is a modified 7-point Likert scale of -perceived change. Response options include: (1) much better, (2) somewhat better, (3) slightly better), (4) neither better nor worse, (5) slightly worse, (6) somewhat worse, (7) much worse. The response rate was defined as the number of participants self-reporting at least "slightly better" divided by the number of participants in each treatment group. Th

Time frame:: After the 8 week FD phase and four week post-tapper
Reported as:: Count of participants · Participants

Clinical Global Impression of Improvement Scale (CGI-I)
Participants	Gabapentin	Placebo
Fixed Dose Period	8	20
4 week post tapper	7	12

SecondaryUniversity of Pennsylvania Smell Identification Test (UPSIT)

Forty different odors are presented in this test. Scoring: Forced choice of 4 responses to identify each smell. Anosmia: score 6-18; severe microsmia: score 19-25, moderate microsmia: 26-30 in women and 26-29 in men; mild microsmia: 31-34 in women and 30-33 in men; and normosmia: score \> 34 in women and \>33 in men. The total UPSIT score can range from 0 to 40 and scores. The MCID in UPSIT score is 4. Scores are interpreted as the level of absolute smell function (i.e., normosmia, mild hyposmia, moderate hyposmia, severe hyposmia, and anosmia), using the age- and sex-related normative classification system described in the UPSIT manual (Table 1)

Time frame:: Baseline, after completion of eight-week fixed-dose period, and 4 weeks after completion of taper-down period
Reported as:: Median · score on a scale (0-40)

University of Pennsylvania Smell Identification Test (UPSIT)
score on a scale (0-40)	Gabapentin	Placebo
Baseline	23 (10 to 31)	24 (7 to 34)
Fixed Dose	25 (12 to 34)	25 (15 to 34)
Post-taper	26 (7 to 33)	25 (9 to 35)

SecondaryOlfactory Dysfunction Outcomes Rating (ODOR)

The ODOR questionnaire is a validated 28-item patient-reported outcome measure which assesses the physical, functional, and emotional consequences of OD. The ODOR is a 28-item instrument with each item scored as either no difficulty or very rarely bothered (0) to complete difficulty or very frequently bothered (4) with a total instrument score range of 0 to 112 points. Higher scores indicate higher degree of dysfunction and limitation. the MCID is 15 points.

Time frame:: Baseline, after completion of eight-week fixed-dose period, and 4 weeks after completion of taper-down period
Reported as:: Median · score on a scale (0-112)

Olfactory Dysfunction Outcomes Rating (ODOR)
score on a scale (0-112)	Gabapentin	Placebo
Baseline	23 (10 to 31)	54.5 (30 to 96)
Fixed Dose	25.5 (15 to 34)	49.9 (8 to 96)
Post Taper	25 (9 to 35)	45 (8 to 85)

SecondaryNASAL-7

NASAL-7 is a simple diagnostic tool for olfactory dysfunction that is based on commonly found household items and can be used by adults who suspect olfactory dysfunction. The NASAL-7 was developed by Dr. Piccirillo and colleagues in the Clinical Outcomes Research Office. The NASAL-7, contains 7 household items with each item scored as 0 for 'Cannot Smell', 1 for 'Smells Less Strong/Different Than Normal', and 2 for 'Smells Normal', for a total possible score ranging from 0-14. The following four categories of olfactory function were defined based on NASAL-7 score: anosmia (score 0-4), severe dysfunction (score 5-7), mild dysfunction (score 8-10), and normosmia (score 11-14).

Time frame:: Baseline, after completion of eight-week fixed-dose period, and 4 weeks after completion of taper-down period
Reported as:: Count of participants · Participants

NASAL-7
Participants	Gabapentin	Placebo
Baseline — Anosmia (0-4)	6	10
Baseline — Severe dysfunction (5-7)	8	12
Baseline — Mild dysfunction (8-10)	2	3
Baseline — Normosmia (11-14)	2	1
Fixed Dose — Anosmia (0-4)	4	7
Fixed Dose — Severe dysfunction (5-7)	5	9
Fixed Dose — Mild dysfunction (8-10)	4	6
Fixed Dose — Normosmia (11-14)	5	4
Post taper — Anosmia (0-4)	5	7
Post taper — Severe dysfunction (5-7)	6	6
Post taper — Mild dysfunction (8-10)	2	5
Post taper — Normosmia (11-14)	3	7

SecondaryCGI-Severity of Smell

CGI-Severity. The CGI-Severity scale ranges from 1 to 7, where 1 is normal function and 7 is complete anosmia. This assessment will provide subjective data on patients' baseline olfactory function prior to beginning the trial, after 8-week Fixed-Dose period, and 4 weeks after completion of Taper-Down phase

Time frame:: 8-week Fixed-Dose period, and 4 weeks after completion of Taper-Down phase
Reported as:: Count of participants · Participants

CGI-Severity of Smell
Participants	Gabapentin	Placebo
Assessments of the Secondary Outcome Measures of Study Groups: Baseline — Absent	4	4
Assessments of the Secondary Outcome Measures of Study Groups: Baseline — Poor	12	16
Assessments of the Secondary Outcome Measures of Study Groups: Baseline — Fair	1	4
Assessments of the Secondary Outcome Measures of Study Groups: Baseline — Good	1	1
Assessments of the Secondary Outcome Measures of Study Groups: Baseline — Very good	0	1
Assessments of the Secondary Outcome Measures of Study Groups: Baseline — Excellent	0	0
Fixed Dose — Absent	3	5
Fixed Dose — Poor	4	13
Fixed Dose — Fair	8	4
Fixed Dose — Good	3	3
Fixed Dose — Very good	0	1
Fixed Dose — Excellent	0	0
Post taper — Absent	2	3
Post taper — Poor	7	13
Post taper — Fair	5	6
Post taper — Good	2	2
Post taper — Very good	0	1
Post taper — Excellent	0	0

SecondaryCGI-S of Parosmia

Clinical Global Impression-Severity Scale for Parosmics (CGI-P). The CGI-P Scale is a global rating of parosmia and the single global rating ranges from 1-5, where 1 is No Distortion, 2 is Mild Distortion, 3 is Moderate Distortion, 4 is Mostly Distorted, and 5 is Complete Distortion. The response on the CGI-P will provide information on the patient's perceived severity of the distortion of their smell.

Time frame:: 8-week Fixed-Dose period, and 4 weeks after completion of Taper-Down phase
Reported as:: Count of participants · Participants

CGI-S of Parosmia
Participants	Gabapentin	Placebo
Assessments of Secondary Outcome Measures of Study Groups: Baseline — Complete Distortion	7	6
Assessments of Secondary Outcome Measures of Study Groups: Baseline — Mostly Distorted	9	8
Assessments of Secondary Outcome Measures of Study Groups: Baseline — Moderate Distortion	2	7
Assessments of Secondary Outcome Measures of Study Groups: Baseline — Mild Distortion	0	4
Assessments of Secondary Outcome Measures of Study Groups: Baseline — No Distortion	0	1
Fixed Dose — Complete Distortion	2	3
Fixed Dose — Mostly Distorted	6	6
Fixed Dose — Moderate Distortion	4	9
Fixed Dose — Mild Distortion	5	7
Fixed Dose — No Distortion	1	1
Post tapper — Complete Distortion	2	2
Post tapper — Mostly Distorted	5	9
Post tapper — Moderate Distortion	6	9
Post tapper — Mild Distortion	2	4
Post tapper — No Distortion	1	1

Adverse events

Collected over If tolerated, all participants will complete the Titration period (≤ 4 weeks), Fixed-Dose period (8 weeks), and Taper-Down period (2 weeks) for maximum 14 weeks of active participation. In addition, there will be a 4-week, post-Taper completion follow-up for maximum total of 18-week trial duration. Non-serious events are listed at a 0% frequency threshold.

Adverse event summary by group
Group	Deaths	Serious	Other
Gabapentin	0/18 (0%)	0/18 (0%)	10/18 (55.6%)
Placebo	0/26 (0%)	0/26 (0%)	11/26 (42.3%)

Most frequent other events

Most frequent other events
Event	Gabapentin	Placebo
fatigueInvestigations	10/18	11/26
dizzinessInvestigations	6/18	0/26
brain fogInvestigations	6/18	2/26
weight gainInvestigations	5/18	0/26

Baseline characteristics

Thirty-four participants were randomized to gabapentin and 34 were randomized to placebo.

Age, Continuous
Age, Continuous(years)	Gabapentin	Placebo	Total
Mean	42 ± 10.6	44 ± 15.5	43 ± 13.5

Sex: Female, Male
Sex: Female, Male(Participants)	Gabapentin	Placebo	Total
Female	26	25	51
Male	8	9	17

Race (NIH/OMB)
Race (NIH/OMB)(Participants)	Gabapentin	Placebo	Total
American Indian or Alaska Native	0	0	0
Asian	0	0	0
Native Hawaiian or Other Pacific Islander	0	0	0
Black or African American	2	0	2
White	23	33	56
More than one race	0	0	0
Unknown or Not Reported	2	1	3

Race/Ethnicity, Customized
Race/Ethnicity, Customized(Participants)	Gabapentin	Placebo	Total
White	23	33	56
Black / African American	2	0	2
Hispanic	0	1	1
Other	2	0	2

Region of Enrollment
Region of Enrollment(participants)	Gabapentin	Placebo	Total
United States	34	34	68

University of Pennsylvania Smell Identification Test (UPSIT)
University of Pennsylvania Smell Identification Test (UPSIT)(score on a scale (0-40))	Gabapentin	Placebo	Total
Median	24.5 (8 to 33)	25.5 (7 to 34)	25.0 (7.0 to 34.0)

Olfactory Dysfunction Outcomes Rating (ODOR)
Olfactory Dysfunction Outcomes Rating (ODOR)(score on a scale (0-112))	Gabapentin	Placebo	Total
Median	56 (14 to 102)	54.5 (0 to 101)	56 (0 to 102)

NASAL-7 categories
NASAL-7 categories(Participants)	Gabapentin	Placebo	Total
Anosmia (0-4)	9	11	20
Severe dysfunction (5-7)	12	16	28
Mild dysfunction (8-10)	4	5	9
Normosmia (11-14)	2	2	4

2 further baseline measures are reported on the registry.

Study locations

1 site

Washington University
Saint Louis, Missouri 63110, United States

References and documents

Publications

Lechien JR, Chiesa-Estomba CM, De Siati DR, Horoi M, Le Bon SD, Rodriguez A, Dequanter D, Blecic S, El Afia F, Distinguin L, Chekkoury-Idrissi Y, Hans S, Delgado IL, Calvo-Henriquez C, Lavigne P, Falanga C, Barillari MR, Cammaroto G, Khalife M, Leich P, Souchay C, Rossi C, Journe F, Hsieh J, Edjlali M, Carlier R, Ris L, Lovato A, De Filippis C, Coppee F, Fakhry N, Ayad T, Saussez S. Olfactory and gustatory dysfunctions as a clinical presentation of mild-to-moderate forms of the coronavirus disease (COVID-19): a multicenter European study. Eur Arch Otorhinolaryngol. 2020 Aug;277(8):2251-2261. doi: 10.1007/s00405-020-05965-1. Epub 2020 Apr 6. PubMed 32253535 ↗
Boscolo-Rizzo P, Borsetto D, Fabbris C, Spinato G, Frezza D, Menegaldo A, Mularoni F, Gaudioso P, Cazzador D, Marciani S, Frasconi S, Ferraro M, Berro C, Varago C, Nicolai P, Tirelli G, Da Mosto MC, Obholzer R, Rigoli R, Polesel J, Hopkins C. Evolution of Altered Sense of Smell or Taste in Patients With Mildly Symptomatic COVID-19. JAMA Otolaryngol Head Neck Surg. 2020 Aug 1;146(8):729-732. doi: 10.1001/jamaoto.2020.1379. PubMed 32614442 ↗
Hummel T, Rissom K, Reden J, Hahner A, Weidenbecher M, Huttenbrink KB. Effects of olfactory training in patients with olfactory loss. Laryngoscope. 2009 Mar;119(3):496-9. doi: 10.1002/lary.20101. PubMed 19235739 ↗
Turner JH. Olfactory training: what is the evidence? Int Forum Allergy Rhinol. 2020 Nov;10(11):1199-1200. doi: 10.1002/alr.22681. Epub 2020 Sep 3. No abstract available. PubMed 32776673 ↗
Biole C, Bianco M, Nunez-Gil IJ, Cerrato E, Spirito A, Roubin SR, Viana-Llamas MC, Gonzalez A, Castro-Mejia AF, Eid CM, Fernandez-Perez C, Uribarri A, Alfonso-Rodriguez E, Ugo F, Guerra F, Feltes G, Akin I, Fernandez-Rozas I, Blasco-Angulo N, Huang J, Aguado MG, Pepe M, Romero R, Becerra-Munoz VM, Estrada V, Macaya C. Gender Differences in the Presentation and Outcomes of Hospitalized Patients With COVID-19. J Hosp Med. 2021 Jun;16(6):349-352. doi: 10.12788/jhm.3594. PubMed 34129486 ↗
Butowt R, von Bartheld CS. Anosmia in COVID-19: Underlying Mechanisms and Assessment of an Olfactory Route to Brain Infection. Neuroscientist. 2021 Dec;27(6):582-603. doi: 10.1177/1073858420956905. Epub 2020 Sep 11. PubMed 32914699 ↗
Bilinska K, Butowt R. Anosmia in COVID-19: A Bumpy Road to Establishing a Cellular Mechanism. ACS Chem Neurosci. 2020 Aug 5;11(15):2152-2155. doi: 10.1021/acschemneuro.0c00406. Epub 2020 Jul 16. PubMed 32673476 ↗
Kuba K, Imai Y, Penninger JM. Multiple functions of angiotensin-converting enzyme 2 and its relevance in cardiovascular diseases. Circ J. 2013;77(2):301-8. doi: 10.1253/circj.cj-12-1544. Epub 2013 Jan 18. PubMed 23328447 ↗
Mollica V, Rizzo A, Massari F. The pivotal role of TMPRSS2 in coronavirus disease 2019 and prostate cancer. Future Oncol. 2020 Sep;16(27):2029-2033. doi: 10.2217/fon-2020-0571. Epub 2020 Jul 13. No abstract available. PubMed 32658591 ↗
Damm M, Pikart LK, Reimann H, Burkert S, Goktas O, Haxel B, Frey S, Charalampakis I, Beule A, Renner B, Hummel T, Huttenbrink KB. Olfactory training is helpful in postinfectious olfactory loss: a randomized, controlled, multicenter study. Laryngoscope. 2014 Apr;124(4):826-31. doi: 10.1002/lary.24340. Epub 2013 Sep 19. PubMed 23929687 ↗
Schopf CL, Ablinger C, Geisler SM, Stanika RI, Campiglio M, Kaufmann WA, Nimmervoll B, Schlick B, Brockhaus J, Missler M, Shigemoto R, Obermair GJ. Presynaptic alpha2delta subunits are key organizers of glutamatergic synapses. Proc Natl Acad Sci U S A. 2021 Apr 6;118(14):e1920827118. doi: 10.1073/pnas.1920827118. PubMed 33782113 ↗
Lopez-D'alessandro E, Escovich L. Combination of alpha lipoic acid and gabapentin, its efficacy in the treatment of Burning Mouth Syndrome: a randomized, double-blind, placebo controlled trial. Med Oral Patol Oral Cir Bucal. 2011 Aug 1;16(5):e635-40. doi: 10.4317/medoral.16942. PubMed 20711135 ↗
Doty RL, Shaman P, Kimmelman CP, Dann MS. University of Pennsylvania Smell Identification Test: a rapid quantitative olfactory function test for the clinic. Laryngoscope. 1984 Feb;94(2 Pt 1):176-8. doi: 10.1288/00005537-198402000-00004. PubMed 6694486 ↗
Doty RL. Olfactory dysfunction and its measurement in the clinic. World J Otorhinolaryngol Head Neck Surg. 2015 Oct 26;1(1):28-33. doi: 10.1016/j.wjorl.2015.09.007. eCollection 2015 Sep. PubMed 29204537 ↗
Mersfelder TL, Nichols WH. Gabapentin: Abuse, Dependence, and Withdrawal. Ann Pharmacother. 2016 Mar;50(3):229-33. doi: 10.1177/1060028015620800. Epub 2015 Dec 31. PubMed 26721643 ↗

Study documents

Protocol and statistical analysis plan ↗ · Jun 20, 2022

PDFs hosted by the registry, ClinicalTrials.gov.

Individual participant data

Plan to share: No

Timeline

Tracking since Sep 25, 2026

ElapsedEstimatedEstimated, not yet reachedSimilar studies: half by the dot; the band is the middle halfHalf of similar studies reached it by the dot; the band is the middle half, from a quarter to three quarters

Ran from Jan 2022 to primary completion in Aug 2023, 19 months.

Results were first posted in Mar 2025, 1 year 6 months after primary completion.

Of 359 non-industry phase 2 interventional studies under COVID-19, half reached primary completion within 11 months of starting (the median), counting those still running; a quarter within 5 and three quarters within 18. This study's 19 months is above that.

Counting every sponsor, half of 582 studies reached it within 9 months; a quarter within 5 and three quarters within 16.

How these figures are worked out, and which studies are left out of them.

Registered: Jan 6, 2022
First posted: Jan 11, 2022
StartActual: Jan 10, 2022
Primary completionActual: Aug 29, 2023
CompletionActual: Aug 29, 2023
Results first posted: Mar 4, 2025
Last update: Mar 4, 2025

What these dates mean

Start.: When the first participant enrolled; while estimated, when the study expects to open to recruitment.
Primary completion.: When the last participant was examined or treated to collect data for the study's main question, its primary outcome. A study that stopped early gives the date its data collection stopped.
Completion.: When the last participant's last visit took place, for every outcome, secondary ones and side effects included: the end of the study. Often later than primary completion, sometimes the same day.
Actual and Est.: Actual means the registry says the date has happened. Est. (estimated) is a date the sponsor plans or expects. It can still move, and the sponsor is expected to change it to actual once it has passed.

No changes since tracking began. The registry record was last updated on Mar 4, 2025, before this site started recording changes on Sep 25, 2026. Its history is on ClinicalTrials.gov ↗

Registry details

Key details

Study ID: NCT05184192
Lead sponsor: Washington University School of Medicine
Responsible party: Sponsor
First posted: Jan 11, 2022
Start date: Jan 10, 2022
Primary completion: Aug 29, 2023
Completion: Aug 29, 2023
Results posted: Mar 4, 2025
Last update: Mar 4, 2025

Study contacts

Jay F Piccirillo, MD

principal investigator · Washington University School of Medicine

Oversight

Data monitoring committee: Yes
FDA-regulated drug: Yes
FDA-regulated device: No

View the source record on ClinicalTrials.gov ↗

Not currently enrolling

This study is completed, as verified in Feb 2025. You cannot join it, but the record below documents what was studied.

Follow this study

Get an email when the registry record changes — status, dates, results — or when someone posts here.

Discussion

Questions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.

Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.

Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.

Other studies in this condition

COVID-19 →

Other studies from this sponsor

Washington University School of Medicine →

Start the discussion