Adcirca (tadalafil) improved the pulmonary arterial hypertension (PAH) of 29 percent of patients in a real-world study in Japan, researchers said.
They two-year study also found the treatment to be safe, with acceptable rates of side effects.
A real-world study covers a patient group with a wider range of characteristics than a clinical trial. This increases the chance that researchers will detecting new risks linked to the treatment. But the study did not identify new side effects of Adcirca.
The research, “Safety and effectiveness of tadalafil in patients with pulmonary arterial hypertension; Japan post- marketing surveillance data,“ was published in the journal Current Medical Research and Opinion.
Researchers at Eli Lilly followed about 1,800 patients in clinics across Japan. They were able to collect safety data from 1,676 patients.
The average age of the group was 43.5 years old. The study had a good representation of age groups, researchers said. Twenty-three percent of patients were younger than 18, and 29 percent were 65 or older.
Nearly two-thirds of the patients were women.
Most patients were in the mid-range WHO functional classes 2 and 3, but patients with mild and severe PAH also participated. The vast majority of patients took other drugs as well as Adcirca during the study period.
Among the 1,676 patients, 611 stopped taking Adcirca during the two years. About half said it was because of side effects.
Fifty-nine patients said they stopped taking Adcirca because it had improved their condition. Thirty-six dropped it because it failed to help them. Other reasons patients stopped taking Adcirca included changing treatments or hospitals, or dropping out of the study.
Adverse events that made people get off Adcirca were most often headache, cardiac failure, worsening of PAH and lung hypertension, nausea, diarrhea, and interstitial lung disease. Headache was the most common reason, affecting 2 percent of the group that stopped.
Researchers noted new adverse events in 31.2 percent of the entire group. Severe adverse events occurred in 7.1 percent of cases.
The most common adverse events were headache, diarrhea, decreased platelet count, anemia, nosebleeds, nausea, flushing, abnormal liver function, hot flush, and muscle pain. The most common severe adverse events were cardiac failure, and worsening PAH and interstitial lung disease. They affected between 0.3% and 0.7% of patients.
Many of the side effects — headache, nausea, diarrhea, muscle pain, flushing, and hot flushes — appeared early on during treatment and decreased over time, however. In patients treated for more than a year, the adverse event rate was 8 percent, with serious adverse events occurring in 2.4 percent of patients.
Some effects failed to decrease over time. They included lower blood platelet count, anemia, nosebleeds, and abnormal liver function. Since these symptoms can also be an effect of PAH, it was impossible for the researchers to conclude if they were caused by the medication or not.
The research team analyzed the effectiveness of Adcirca in 1,556 patients. At two years, 29 percent had improved their WHO functional class standing. There was a steady increase in functional class improvement between three months, one year and two years.
Meanwhile, the percentage of patients who got worse despite the treatment also increased, from 1.7 percent at three months to 4 percent at two years.
Patients also improved in the six-minute walk test, a measure of exercise capacity. In addition, right heart catheterization and echocardiogram measurements showed patient improvement in several lung and heart parameters, including pulmonary arterial pressure.
Eighty-six percent of patients had survived after two years, compared with a one-year rate of 93 percent.
Since the causes of PAH differ between young and old patients, researchers said there could have been drug effectiveness and safety differences between the groups that the study did not pick up.
To get a better grasp on potential differences, the team plans to continue analyzing data on children and adolescents in the study.
Adcirca is marketed in the U.S. by Lung Biotechnology.