Adempas (riociguat) is a prescription medication manufactured by Bayer used to treat two forms of pulmonary hypertension:

• Chronic thromboembolic pulmonary hypertension (CTEPH) — Adempas is the only FDA-approved medication for adults with inoperable or persistent/recurrent CTEPH after surgery, to improve exercise capacity and WHO functional class.
• Pulmonary arterial hypertension (PAH) — Adempas is approved to improve exercise capacity, improve WHO functional class, and delay clinical worsening in adults with PAH (WHO Group 1).

Both conditions involve dangerously high blood pressure in the arteries of the lungs, which forces the heart to work harder and can lead to heart failure. Adempas helps relax and widen these blood vessels to reduce the strain on the heart and improve blood flow.

Adempas is a soluble guanylate cyclase (sGC) stimulator — the first and only drug in its class approved for pulmonary hypertension. It works through a unique dual mechanism:

1. Sensitizes sGC to nitric oxide (NO) — It enhances the enzyme's response to the body's natural nitric oxide signaling.
2. Directly stimulates sGC — It can also activate the enzyme independently of nitric oxide.

When sGC is stimulated, it increases production of cyclic guanosine monophosphate (cGMP), a molecule that relaxes smooth muscle cells in blood vessel walls. This leads to vasodilation (widening of the pulmonary arteries), reduced pulmonary vascular resistance, and improved blood flow through the lungs. This dual mechanism distinguishes Adempas from PDE-5 inhibitors like sildenafil, which only work downstream in the same pathway.

• 0.5 mg tablets
• 1 mg tablets
• 1.5 mg tablets
• 2 mg tablets
• 2.5 mg tablets

Adempas is taken three times daily. The typical starting dose is 1 mg three times a day, with gradual titration up to a maximum of 2.5 mg three times a day based on blood pressure tolerance.

Adempas has a Findability Score of 35 out of 100, meaning it is frequently difficult to access. This is not due to a traditional drug shortage — Adempas is not currently listed on the FDA shortage database. Instead, access challenges are structural: Adempas is distributed exclusively through REMS-certified specialty pharmacies, requires prior authorization from insurance, and carries a cash price exceeding $14,000 per month. While a generic version of riociguat has been approved, it is not yet commercially available. Patients may experience significant delays due to the specialty pharmacy enrollment process, insurance hurdles, and the limited distribution network.

Adempas is prescribed by specialists with expertise in pulmonary hypertension, including:

• Pulmonologists — Lung specialists who diagnose and manage pulmonary vascular diseases.
• Cardiologists — Particularly those specializing in pulmonary hypertension or right heart failure.
• Pulmonary hypertension specialists — Physicians at designated PH care centers who manage complex cases.

Due to the REMS program requirements and the complexity of treating PAH and CTEPH, Adempas is almost always initiated and managed at specialized pulmonary hypertension centers rather than by general practitioners.

No, Adempas is not a controlled substance under the DEA schedule. However, it is subject to a Risk Evaluation and Mitigation Strategy (REMS) program called the Adempas REMS Program. This means:

• Only certified prescribers enrolled in the REMS program can write prescriptions for Adempas.
• Only certified specialty pharmacies can dispense it.
• Patients must be enrolled in the program and meet specific requirements before receiving the medication.

The REMS restriction exists primarily because of the drug's boxed warning for embryo-fetal toxicity — Adempas can cause serious birth defects and must not be used during pregnancy. Female patients of reproductive potential must have negative pregnancy tests and use acceptable contraception. These distribution controls make Adempas harder to access than a typical prescription but serve an important safety function.

Like all medications, Adempas can cause side effects. The most commonly reported include:

• Headache — The most frequent side effect, often improving over time.
• Dizziness and lightheadedness — Related to the blood pressure-lowering effect.
• Low blood pressure (hypotension) — Can cause fainting in some patients.
• Digestive issues — Including nausea, diarrhea, vomiting, dyspepsia (indigestion), and gastroesophageal reflux (GERD).
• Anemia — Low red blood cell counts may occur during treatment.

Serious side effects to watch for include:

• Symptomatic hypotension — Dangerously low blood pressure that may require dose adjustment.
• Pulmonary hemorrhage — Serious bleeding in the lungs, particularly in patients with certain risk factors.
• Embryo-fetal toxicity (Boxed Warning) — Adempas must not be taken during pregnancy as it can cause serious harm to an unborn baby.

The gradual dose titration schedule (starting at 1 mg TID and increasing slowly) is designed to minimize blood pressure-related side effects. Report any concerning symptoms to your doctor promptly.

If you're having difficulty accessing Adempas, there are other FDA-approved medications for pulmonary arterial hypertension, though none share Adempas's unique mechanism of action and no other drug is approved for CTEPH:

• Bosentan (Tracleer) — An endothelin receptor antagonist (ERA) available in generic form.
• Ambrisentan (Letairis) — Another ERA with once-daily dosing.
• Macitentan (Opsumit) — A newer ERA with tissue-targeting properties.
• Selexipag (Uptravi) — A selective prostacyclin IP receptor agonist available as oral tablets.
• Treprostinil — A prostacyclin analog available in inhaled (Tyvaso), oral (Orenitram), subcutaneous, and IV formulations.

Important: Switching from Adempas requires careful medical supervision. Adempas is contraindicated with PDE-5 inhibitors (such as sildenafil/Revatio or tadalafil/Adcirca), so these common PAH drugs cannot be used as alternatives while on Adempas, and a washout period is needed when transitioning. Always consult your pulmonary hypertension specialist before making any medication changes.

Adempas has several important drug interactions that patients and prescribers must be aware of:

Contraindicated combinations (must NOT be used together):

• Nitrates — Including nitroglycerin, isosorbide mononitrate, isosorbide dinitrate, and recreational "poppers" (amyl nitrite). The combination can cause life-threatening drops in blood pressure.
• PDE-5 inhibitors — Including sildenafil (Viagra, Revatio), tadalafil (Cialis, Adcirca), and vardenafil (Levitra). These drugs work on the same pathway and the combination causes excessive hypotension.
• Other sGC stimulators — No other soluble guanylate cyclase stimulators should be combined with Adempas.

Other significant interactions:

• Strong CYP and P-gp/BCRP inhibitors — Drugs like ketoconazole and ritonavir can significantly increase Adempas blood levels.
• Antacids — Aluminum/magnesium hydroxide antacids can reduce Adempas absorption; take them at least one hour apart.
• Smoking — Tobacco smoking reduces Adempas blood levels; dose adjustments may be needed when starting or stopping smoking.
• Antihypertensives — Other blood pressure-lowering medications may have additive effects.

Always provide your healthcare team with a complete list of all medications, supplements, and over-the-counter products you take.

Adempas is a groundbreaking medication — particularly for CTEPH patients, where it remains the only FDA-approved pharmaceutical treatment. However, accessing it can be genuinely challenging. The combination of REMS restrictions, specialty pharmacy-only distribution, high cost, and insurance prior authorization requirements means patients often face weeks-long waits to start therapy.

Tips to improve your access:

• Work with your PH center's pharmacy coordinator — They navigate the REMS enrollment and prior authorization process daily.
• Enroll in the Bayer Adempas Support Program — Provides co-pay assistance and help with insurance appeals.
• Apply for patient assistance — The Bayer Patient Assistance Foundation, PAN Foundation, and HealthWell Foundation may help cover costs for qualifying patients.
• Start the process early — REMS enrollment and specialty pharmacy setup take time, so begin as soon as Adempas is prescribed.
• Keep communication open — Stay in regular contact with your specialty pharmacy to track your prescription status.

If you're struggling to find or afford Adempas, Medfinder can help connect you with available options. Don't give up — this is a life-changing medication for many patients, and support programs exist to help you get it.