A Phase 2 interventional study of Duloxetine 30 MG and Duloxetine 60 MG in Refractory Chronic Cough, sponsored by Mayo Clinic. Recruiting at 1 site in United States. Open to participants aged 18 Years to 75 Years. Per ClinicalTrials.gov, last updated 2026-01-21.
Sponsored by Mayo Clinic · Phase 2, Interventional, and Treatment
This research study is evaluating the effectiveness of escalating doses of Amitriptyline and Duloxetine in reducing cough frequency in patients with refractory chronic cough (RCC)
This is a randomized, double-blind, placebo-controlled, parallel-arm, dose escalation study of Duloxetine \& Amitriptyline in subjects with refractory chronic cough. Subjects will be screened during a period of up to 2 week and will undergo screening/ baseline cough monitoring. A total of 50 subjects who meet entry criteria will be randomly assigned in a 1: 1: 1: 1: 1 ratio to one of five treatment arms using stratified randomization in blocks of 10. Each arm will have two successive 4-week treatment periods (Blinded Period 1 \& 2). After this, patients will be unblinded and receive routine clinical care. During the unblinded (routine clinical care) follow up phase; subjects will be initially offered the option of continuing amitriptyline or duloxetine based on their initial randomization arm. Subjects could also choose an alternative chronic cough therapy (e.g. pregabalin, gabapentin, 1% tetracaine lollipop or nebulized lidocaine or combination therapy).
Subjects in treatment arm 5, who received placebo during the 8 weeks blinded period will have a discussion regarding all available cough therapies. Patients will be offered the flexibility of therapy options during the unblinded follow up as they would during routine clinical care. Participation in the unblinded follow-up period will be optional.
Treatment Arm 1:
Blinded Period 1 (1st 4 weeks): 30mg of Duloxetine Blinded Period 2 (2nd 4 weeks): 30mg of Duloxetine \& 30mg of Placebo Unblinded (routine clinical care) follow up period: (up to 52 weeks): Subjects will be offered routine clinical care management for their chronic cough
Treatment Arm 2:
Blinded Period 1 (1st 4 weeks): 30mg of Duloxetine Blinded Period 2 (2nd 4 weeks): 60mg of Duloxetine (2 pills of 30mg each) Unblinded (routine clinical care) follow up period: (up to 52 weeks): Subjects will be offered routine clinical care management for their chronic cough
Treatment Arm 3:
Blinded Period 1 (1st 4 weeks): 25mg of Amitriptyline Blinded Period 2 (2nd 4 weeks): 25mg of Amitriptyline + 25mg of Placebo Unblinded (routine clinical care) follow up period: (up to 52 weeks): Subjects will be offered routine clinical care management for their chronic cough
Treatment Arm 4:
Blinded Period 1 (1st 4 weeks): 25mg of Amitriptyline Blinded Period 2 (2nd 4 weeks): 50mg of Amitriptyline (2 pills of 25mg each) Unblinded (routine clinical care) follow up period: (up to 52 weeks): Subjects will be offered routine clinical care management for their chronic cough
Treatment Arm 5:
Blinded Period 1 (1st 4 weeks): 30mg of Placebo Blinded Period 2 (2nd 4 weeks): 60mg of Placebo (2 pills of 30mg each) Unblinded (routine clinical care) follow up period: (up to 52 weeks): Subjects will be offered routine clinical care management for their chronic cough
142 studies on the registry are indexed under Chronic Cough; 39 are open to participants now.
This study's planned enrollment of 50 is below the median of 60 across 104 interventional studies indexed under Chronic Cough.
Browse Chronic Cough studies →Mayo Clinic is the lead sponsor of 3,269 studies on the registry; 672 are open to participants now.
Of its 452 completed or terminated interventional studies of FDA-regulated products, 321 (71%) have results posted.
Counted across the registry records on this site, refreshed daily.
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.
Exclusion Criteria
The following therapies are prohibited from 2 week prior to the Screening/Baseline Visit (Day -14 to Day 0) through the end of the 8-week blinded treatment period.
The following therapies are prohibited from 4 week prior to the Screening/Baseline Visit (Day -14 to Day 0) through the end of the 8-week blinded treatment period.
The following therapies are prohibited from 12 week prior to the Screening/Baseline Visit (Day -14 to Day 0) through the end of the 8-week blinded treatment period.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
From a breathing test (spirometry): how much air you can blow out in the first second. Often given as a percentage of what is expected for your age, height and sex.
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Relapsed and refractory
Relapsed: the illness came back after treatment had worked. Refractory: it did not respond to treatment, or stopped responding while still on it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Childbearing potential
Able to become pregnant: from the first period until menopause, unless permanently unable to through surgery (removal of the womb, or of both ovaries or both fallopian tubes).
Criteria for people of childbearing potential usually ask for a negative pregnancy test and for contraception during the study and for a time after it.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Contraception
Ways of preventing pregnancy. “Highly effective” methods fail less than 1% of the time a year when used correctly — for example an IUD or an implant.
Criteria usually say which methods count and how long to keep using them after the last dose, sometimes for male participants too. Some studies accept a partner’s vasectomy if it was confirmed successful and that person is the participant’s only sexual partner.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
FEV1
From a breathing test (spirometry): how much air you can blow out in the first second. Often given as a percentage of what is expected for your age, height and sex.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
COPD
Chronic obstructive pulmonary disease: long-term lung disease that makes it hard to breathe out, including emphysema and chronic bronchitis.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Subjects will receive 30mg of Duloxetine for blinded period 1 (first 4 week treatment period) and 30mg of Duloxetine plus 30mg Placebo for blinded period 2 (additional 4 week treatment period). After this, subjects will be unblinded and receive routine clinical care for follow up phase (up to 52 weeks).
Drug: Duloxetine 30 MG · Drug: Placebo 30 MG
Subjects will receive 30mg of Duloxetine for blinded period 1 (first 4 week treatment period) and 60mg of Duloxetine for blinded period 2 (additional 4 weeks treatment period). After this, subjects will be unblinded and receive routine clinical care for follow up phase (up to 52 weeks).
Drug: Duloxetine 30 MG · Drug: Duloxetine 60 MG
Subjects will receive 25mg of Amitriptyline for blinded period 1 (first 4 week treatment period) and 25mg of Amitriptyline plus 30mg Placebo for blinded period 2 (additional 4 week treatment period). After this, subjects will be unblinded and receive routine clinical care for follow up phase (up to 52 weeks).
Drug: Amitriptyline 25 MG · Drug: Placebo 30 MG
Subjects will receive 25mg of Amitriptyline for blinded period 1 (first 4 week treatment period) and 50mg of Amitriptyline for blinded period 2 (additional 4 weeks treatment period). After this, subjects will be unblinded and receive routine clinical care for follow up phase (up to 52 weeks).
Drug: Amitriptyline 25 MG · Drug: Amitriptyline 50 MG
Subjects will receive 30mg of Placebo for blinded period 1 (first 4 week treatment period) and 60mg of Placebo for blinded period 2 (additional 4 weeks treatment period). After this, subjects will be unblinded and receive routine clinical care for follow up phase (up to 52 weeks).
Drug: Placebo 30 MG · Drug: Placebo 60 MG
30mg orally for 4 weeks
60mg orally for 4 weeks
25 mg orally for 4 weeks
50 mg orally for 4 weeks
30mg tablet with no active study ingredient for 4 weeks
60mg tablet with no active study ingredient for 4 weeks
Change in awake objective cough frequency (at 4 & 8 weeks)
The primary objective is to evaluate awake cough frequency at 4 and 8 weeks using the Leicester Cough Monitor. The acoustic cough monitor recordings will be analyzed using the Leicester Cough Monitor program V2.3-MB. This will also be performed at months 4, 6, 9 \& 12 for subjects who choose to continue with the optional unblinded continuation of the study after the initial 8 weeks.
Time frame: 4 weeks, 8 weeks
Change in 24-Hour cough frequency
This will also be evaluated using using the Leicester Cough Monitor and recordings will be analyzed using the Leicester Cough Monitor program V2.3-MB. All recordings will be kept confidential on a secure encrypted device. This will also be performed at months 4, 6, 9 \& 12 for subjects who choose to continue with the optional unblinded continuation of the study after the initial 8 weeks.
Time frame: 4 weeks, 8 weeks
Change in Cough Severity Diary score
Measured using self-reported Cough Severity Diary that patients will fill at baseline and on daily basis. Change in self-reported Cough Severity Diary score at 4 and 8 weeks will be evaluated. Patients will be asked a series of 6 questions including and will provide an answer using a 5-point Likert scale (never, rarely, sometimes, often, constantly). The following questions will be evaluated: 1. In the past 24 hours, how often did you cough? 2. In the past 24 hours, how often did you experience coughing fits? 3. In the past 24 hours, how severe was your cough? 4. In the past 24 hours, how often did you have an urge to cough? 5. In the past 24 hours, how often could you control your cough? 6. In the past 24 hours, how severe was your pain from coughing? This will also be performed at months 4, 6, 9 \& 12 for subjects who choose to continue with the optional unblinded continuation of the study after the initial 8 weeks.
Time frame: 4 weeks, 8 weeks
Change from Baseline in Leicester Cough Questionnaire (LCQ-acute) individual domain and total scores
The Leicester Cough Questionnaire (Acute) is a validated tool for the assessment of chronic cough. It evaluates physical, psychological and social domains and how they are impacted by chronic cough. The physical domain consists of 8 questions, the psychological domain consists of 7 questions, and the social domain consists of 4 questions. The domain score will be calculated as the total score from questions in the domain divided by the number of items in the domain (range 1-7). The total score is the sum of individual domain scores and ranges from 3-21. The individual domain as well as the total score will be reported on weeks 4 \& 8. This will also be performed at months 4, 6, 9 \& 12 for subjects who choose to continue with the optional unblinded continuation of the study after the initial 8 weeks.
Time frame: 4 weeks, 8 weeks
Change in Cough Severity Visual Analogue Scale (VAS)
Scored on a 100 mm visual analogue scale at Screening/ Baseline visit (Day -14 to Day 0), and on Days 28, and 56. This will also be performed at months 4, 6, 9 \& 12 for subjects who choose to continue with the optional unblinded continuation of the study after the initial 8 weeks.
Time frame: 4 weeks, 8 weeks
Plan to share: No
Started Nov 2021 (actual). Primary completion is estimated for Dec 2026, 61 months after the start.
Of 25 phase 2 interventional studies under Chronic Cough, half reached primary completion within 11 months of starting (the median), counting those still running; a quarter within 10 and three quarters within 21. This study's planned 61 months is above that.
How these figures are worked out, and which studies are left out of them.
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Studies of the drugs tested here: Duloxetine · Amitriptyline