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Inoperable chronic thromboembolic pulmonary hypertension — SCE Respiratory MCQ

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HardPharmacologyInoperable chronic thromboembolic pulmonary hypertensionSCE Respiratory

A 58-year-old man with chronic thromboembolic pulmonary hypertension has been assessed by the national multidisciplinary team. His disease is technically inoperable and not amenable to balloon pulmonary angioplasty. Despite therapeutic warfarin and tadalafil 40 mg once daily, started off-label elsewhere, he remains in WHO functional class III. His resting blood pressure is 108/66 mmHg without postural symptoms. Renal and hepatic function are normal. His other medication is furosemide; he takes no nitrates, azole antifungals or protease inhibitors. The pulmonary hypertension team recommends transition to licensed targeted pharmacotherapy. Which regimen is most appropriate?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: B — Discontinue tadalafil, wait at least 48 hours, then start riociguat 1 mg three times daily with blood-pressure-guided titration

Explanation lettering: B = shown as A · A = shown as B · D = shown as C · E = shown as D · C = shown as E

Riociguat is indicated for symptomatic adult patients with inoperable CTEPH or persistent/recurrent pulmonary hypertension after pulmonary endarterectomy. This patient has undergone expert operability assessment, remains in WHO functional class III and has no listed contraindication to initiation. Tadalafil must be stopped at least 48 hours before riociguat because concomitant PDE5 inhibition and soluble guanylate cyclase stimulation can cause excessive systemic hypotension. The usual starting dose is 1 mg three times daily for 2 weeks, followed by increments of 0.5 mg three times daily at 2-week intervals, according to blood pressure and tolerability, to a maximum of 2.5 mg three times daily. B uses the 24-hour washout specified for sildenafil, not adult tadalafil. C uses the reduced 0.5-mg starting dose considered when riociguat is initiated in a patient receiving a strong multipathway CYP/P-glycoprotein/BCRP inhibitor; none is present here. D is contraindicated because tadalafil and riociguat must not be co-administered, even at a low riociguat dose. E begins immediately at the maximum maintenance dose rather than undertaking individual titration, creating an avoidable risk of hypotension. Therapeutic anticoagulation should continue because riociguat treats the pulmonary microvasculopathy and does not replace anticoagulation for CTEPH.

Reference: Adempas 1.0 mg film-coated tablets — Summary of Product Characteristics (Certified November 2025) — https://www.medicines.org.uk/emc/product/7926/smpc 2022 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension (2022/2023) — https://publications.ersnet.org/content/erj/61/1/2200879