Idiopathic pulmonary fibrosis (IPF) is a disease of unknown cause that results in scarring of the lungs.

Cough is reported by 85% of patients with IPF and can be a distressing symptom with significant physical, social and psychological consequences particularly anxiety and depression.

The cause of cough in IPF is poorly understood and there are currently no proven effective therapies. Morphine has long been advocated for the suppression of chronic cough in other conditions. While morphine is frequently used as a palliative agent for breathlessness in IPF, its effects on cough have never been tested. The aim of this study is therefore to explore and compare the effect of low dose morphine, one of the few therapies shown to be effective in some patients with otherwise refractory chronic cough, in patients with IPF, to an inactive substance known as a placebo.

To make a fair comparison, patients will be randomly allocated to receiving either morphine or placebo in a blinded fashion. This means neither the doctor nor the patient will know which drug they are receiving, and the drugs will appear the same. However, the trial is designed so that you will receive both morphine and placebo, but at different times (this is called a cross-over study). More specifically, you will be given either morphine or placebo for 14 days at a time.

In this study, it is hypothesised that compared with placebo, low dose (5mg) controlled release Morphine sulfate (MST) will reduce the number of coughs recorded during a 24hr period in patients with IPF.

Inclusion Criteria:

1. Self-reported cough (> 8 weeks), with cough VAS ≥ 30/100

2. A diagnosis of IPF within 5 years prior to the screening visit, as per applicable ATS/ERS/JRS/ALAT guidelines, in line with hospital records.

3. Age 3.1. Male and female participants aged ≥ 40 - 90 years at the time of signing informed consent

4. Sex:

   4.1 Male participants: A male participant must agree to use contraception as detailed in Appendix 2 of this protocol during the study and for at least 90 days after the follow-up visit, and refrain from donating sperm during this period 4.2 Female participants: A female participant is eligible to participate if she is not pregnant, not breastfeeding, and not a woman of childbearing potential (WOCBP)

5. Meeting all of the following criteria during the screening period: FVC ≥ 45% predicted of normal, Forced expiratory volume in 1 second (FEV1)/FVC ≥0.7, DLCO corrected for Hb ≥30% predicted of normal.

6. The extent of fibrotic changes is greater than the extent of emphysema on the most recent HRCT scan (investigator determined within 24 months of the study screening visit)

7. Written informed consent.

Exclusion criteria:

1. Treatment with immunosuppressive therapy or antibiotics within last 4 weeks. A stable dose of corticosteroids equivalent to prednisolone of 10 mg per day or less, if used for an indication other than pulmonary disease will be permitted
2. Current smoker
3. History of alcohol and drug(s) addiction
4. Regular use of sedative therapies
5. Acute IPF exacerbation within 6 months prior to screening and/or during the screening period.
6. Concurrent use of pirfenidone or Nintedanib, unless receiving a stable dose for at least 8 weeks prior to screening
7. Use of ACE inhibitors
8. Patients with co-existent conditions know to be associated with the development of fibrotic lung disease. This includes: connective tissue disease, (plural plaques, mesothelioma), granulomatous disease including sarcoidosis. Patient with auto-immune profile considered diagnostic for a specific connective tissue disease will be excluded, even in the absence of systemic symptoms. Non-specific rises in auto antibodies e.g. rheumatoid factors, anti-nuclear antibody etc. will not be used to exclude individuals from the study.
9. Significant other organ co-morbidity including hepatic or renal impairment and pulmonary hypertension (investigator determined).
10. Significant coronary artery disease (myocardial infarction within 6 months or ongoing unstable angina within 4 weeks of screening visit) or congestive cardiac failure based on clinical examination
11. Patients as significant risk of side effects, intolerance or allergy to morphine
12. Pregnant and breastfeeding patients, or women or child-bearing potential, not using a reliable contraceptive method (see Appendix 2). A urine pregnancy test will be performed in females of child-bearing potential at the initial study visit.
13. Unable to provide informed written consent
14. Predicted life expectancy < 6 months
15. Use of long-term oxygen therapy. Use of ambulatory oxygen will be permitted.
16. Current or use of opiates within 14 days of the screening visit.

47 individuals were assessed for eligibility, and 44 were randomly assigned, of whom one withdrew consent before treatment. Of the 43 participants, 21 were randomly allocated to receive morphine in period 1 and then placebo in period 2, and 22 received placebo in period 1 and then morphine in period 2; 43 participants completed morphine treatment. 41 participants completed placebo.

From baseline until event resolution, an average of 30 days

AEs were summarised for Morphine and Placebo arm separately. 43 people received Morphine and 42 received Placebo