Extended-Release Morphine for Chronic Breathlessness in Pulmonary Arterial Hypertension—A Randomized, Double-Blind, Placebo-Controlled, Crossover Study

Abstract

Context

Pulmonary arterial hypertension (PAH) affects people of all ages and is associated with poor prognosis. Chronic breathlessness affects almost all people with PAH.

Objectives

This randomized, placebo-controlled, double-blind, crossover study aimed to evaluate the effects of regular, low-dose, extended-release (ER) morphine for PAH-associated chronic breathlessness.

Methods

Participants with PAH-associated chronic breathlessness were randomized to 1) seven days of ER morphine 20 mg, 2) seven-day washout, and 3) seven days of identically looking placebo, or vice versa. Primary end points were breathlessness “right now”—morning and evening—measured with a Visual Analogue Scale. Secondary end points included additional breathlessness measures, quality of life, function, harms, and blinded treatment preference (ACTRN12609000209291).

Results

Within a period of seven years, 50 patients were assessed in detail and 23 (46%) were randomized (despite broad eligibility criteria). Four participants withdrew while taking morphine. Nineteen participants completed the study. Breathlessness “right now” was higher on morphine compared with placebo both for morning [mean (M) ± SD 31.7 ± 25 mm vs. 26.9 ± 22 mm; effect size (80% CI) = −0.22 (−0.6 to 0.2)] and evening [(M ± SD 33.5 ± 28 mm vs. 25.6 ± 21 mm; effect size (80% CI) = −0.33 (−0.8 to 0.1)]. All secondary measures of breathlessness were higher with morphine as were nausea and constipation.

Conclusion

This study does not support a Phase III study of ER morphine for people with PAH-associated chronic breathlessness. Recruiting to the target sample size was difficult, the direction of effect in every measure of breathlessness favored placebo and morphine generated more harms.