Riociguat belongs to the class of medications called soluble guanylate cyclase stimulators. It works to reduce the blood pressure in the lungs by opening the blood vessels that connect the heart to the lungs. It is used to treat adults with Chronic Thromboembolic Pulmonary Hypertension (CTEPH) where surgery is not possible and with CTEPH that continues or has returned after surgery. It is also used to treat adults who have Pulmonary Arterial Hypertension (PAH), either alone or in combination with other medications.

CTEPH is a rare illness that is caused by blood clots in the blood vessels of the lungs. This restricts blood flow and causes increased blood pressure in the lung vessels. PAH is a disease that is caused by narrowing of the blood vessels in the lungs, causing increased blood pressure in the arteries of the lungs. In both conditions, the heart has to work harder, causing people to feel tired, dizzy, or short of breath.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended starting dose of riociguat is 1 mg taken 3 times daily for 2 weeks. It may be taken with or without food, but should be spaced approximately 6 to 8 hours apart. Your doctor will gradually increase the dose as long as your blood pressure does not become too low or other side effects are not tolerated. The total daily dose should not be more than 7.5 mg (2.5 mg taken 3 times daily).

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important that this medication be taken exactly as prescribed by your doctor. Do not stop taking this medication suddenly, unless you are experiencing serious side effects. If you feel it is necessary to stop taking riociguat, discuss this with your doctor.

If you miss a dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice. If you have missed taking the medication for three days or more, contact your doctor before restarting riociguat.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children. Do not use this medication after the expiry date stated on the label.

0.5 mg
Each film-coated, round, white tablet marked with the Bayer cross on one side and "0.5" and an "R" on the other side contains riociguat 0.5 mg. Nonmedicinal ingredients: cellulose microcrystalline, crospovidone, hydroxypropylcellulose, hypromellose 3cP, hypromellose 5cP, lactose monohydrate, magnesium stearate, propylene glycol, sodium laurilsulphate, and titanium dioxide.

1 mg
Each film-coated, round, pale yellow tablet marked with the Bayer cross on one side and "1" and an "R" on the other side contains riociguat 1 mg. Nonmedicinal ingredients: cellulose microcrystalline, crospovidone, ferric oxide yellow, hydroxypropylcellulose, hypromellose 3cP, hypromellose 5cP, lactose monohydrate, magnesium stearate, propylene glycol, sodium laurilsulphate, and titanium dioxide.

1.5 mg
Each film-coated, round, yellow-orange tablet marked with the Bayer cross on one side and "1.5" and an "R" on the other side contains riociguat 1.5 mg. Nonmedicinal ingredients: cellulose microcrystalline, crospovidone, ferric oxide yellow, hydroxypropylcellulose, hypromellose 3cP, hypromellose 5cP, lactose monohydrate, magnesium stearate, propylene glycol, sodium laurilsulphate, and titanium dioxide.

2 mg
Each film-coated, round, pale orange tablet marked with the Bayer cross on one side and "2" and an "R" on the other side contains riociguat 2 mg. Nonmedicinal ingredients: cellulose microcrystalline, crospovidone, ferric oxide red, ferric oxide yellow, hydroxypropylcellulose, hypromellose 3cP, hypromellose 5cP, lactose monohydrate, magnesium stearate, propylene glycol, sodium laurilsulphate, and titanium dioxide.

2.5 mg
Each film-coated, round, red-orange tablet marked with the Bayer cross on one side and "2.5" and an "R" on the other side contains riociguat 2.5 mg. Nonmedicinal ingredients: cellulose microcrystalline, crospovidone, ferric oxide red, ferric oxide yellow, hydroxypropylcellulose, hypromellose 3cP, hypromellose 5cP, lactose monohydrate, magnesium stearate, propylene glycol, sodium laurilsulphate, and titanium dioxide.

Do not take riociguat if you:

• are allergic to riociguat or any ingredients of the medication
• are pregnant or planning to become pregnant
• are breast-feeding or planning to breast-feed
• are taking any of the following medications:
• phosphodiesterase 5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
• nitrate medications (e.g., nitroglycerin tablet, spray, or ointment)
• nitric oxide donors (e.g., amyl nitrate)
• other soluble guanylate cyclase stimulators (e.g., vericiguat)
• have a history of increased blood pressure in the lungs, associated with scarring of the lungs, caused by non-infectious pneumonia

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• abdominal pain
• bloating
• constipation
• dizziness
• headache
• heartburn
• stomach pain
• swelling of the ankles, legs, hands

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• diarrhea
• difficulty swallowing
• fainting
• fast or irregular heartbeat
• low blood pressure (e.g., dizziness or lightheadedness)
• nasal congestion
• nausea
• nosebleeds that last longer than 5 minutes
• signs of anemia (low red blood cells; e.g., dizziness, pale skin, unusual tiredness or weakness, shortness of breath, headache, unusually fast heartbeat)
• symptoms of acid reflux (e.g., heartburn that gets worse at night, trouble swallowing, sensation of lump in the throat)
• vomiting

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of a serious allergic reaction (e.g., abdominal cramps, difficulty breathing, nausea and vomiting, or swelling of the face and throat)
• signs of bleeding in the lungs (e.g., coughing up blood)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking (including herbal treatments), whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Bleeding: High blood pressure in the lungs tends to cause increased bleeding. This medication may further increase the risk of bleeding, particularly for people with a history of bleeding in the lungs. If you experience an increase in nosebleeds or you begin to cough up blood, contact your doctor immediately as this can become a medical emergency.

Dizziness: Riociguat may cause drowsiness or dizziness, affecting your ability to drive or operate machinery. Avoid these and other hazardous tasks until you have determined how this medication affects you.

Kidney function: Kidney disease or decreased kidney function can cause this medication to build up in the body, causing increased side effects. The safety and effectiveness of using this medication have not been determined for people with severely reduced kidney function or those on dialysis. If you have kidney problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Liver function: Liver disease or decreased liver function can cause this medication to build up in the body, causing increased side effects. The safety and effectiveness of using this medication have not been determined for people with severe liver disease or reduced liver function. If you have liver problems, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Low blood pressure: Riociguat may cause a lowering of blood pressure. If you have low blood pressure (e.g., systolic blood pressure < 95 mmHg), or have existing heart disease (e.g., coronary artery disease, hypovolemia, severe left ventricular outflow obstruction, autonomic dysfunction) or are taking medications that lower blood pressure, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Smoking: Cigarette smoking dramatically reduces how much riociguat is available in your body and may result in this medication not working properly. It is advised that people taking riociguat stop smoking. Discuss this with your doctor or pharmacist.

Pregnancy: This medication should not be used during pregnancy. If you become pregnant while taking this medication, contact your doctor immediately. Anyone who could become pregnant should use effective birth control during treatment with riociguat.

Breast-feeding: It is not known if riociguat passes into breast milk. If you are breast-feeding and taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

Seniors: The effects of this medication on seniors have not been well studied. It is likely that people over the age of 65 will experience more side effects due to the increased likelihood of kidney, liver, or heart disease. Report any unusual effects to your doctor as soon as possible.

There may be an interaction between riociguat and any of the following:

• abacavir
• aldesleukin
• aliskiren
• alpha-agonists (e.g., clonidine, methyldopa)
• alpha-blockers (e.g., alfuzosin, doxazosin, tamsulosin)
• aluminum hydroxide
• amiodarone
• anagrelide
• angiotensin converting enzyme inhibitors (ACEIs; captopril, enalapril, ramipril)
• angiotensin receptor blockers (ARBs; e.g., candesartan, irbesartan, losartan)
• antacids (e.g., aluminum hydroxide, calcium carbonate, magnesium hydroxide)
• antipsychotics (e.g., cariprazine, chlorpromazine, clozapine, olanzapine, quetiapine, risperidone)
• apalutamide
• apomorphine
• apremilast
• "azole" antifungals (e.g., itraconazole, ketoconazole, voriconazole)
• beta blockers (e.g., atenolol, propranolol, sotalol)
• brimonidine
• bromocriptine
• butalbital
• calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
• carbamazepine
• cobicistat
• conivaptan
• crisaborole
• diazoxide
• dipyridamole
• diuretics (water pills; e.g., furosemide, hydrochlorothiazide, triamterene)
• dronedarone
• duloxetine
• elvitegravir
• enzalutamide
• eplerenone
• grapefruit juice
• guanfacine
• hydralazine
• HIV protease inhibitors (e.g., atazanavir, darunavir, lopinavir, ritonavir)
• inhaled anaesthetics (medications to put you to sleep for surgery; halothane, isoflurane)
• iron sucrose
• levodopa
• lumacaftor and ivacaftor
• macrolide antibiotics (clarithromycin, erythromycin)
• magnesium hydroxide
• mifepristone
• minoxidil
• morphine
• nabilone
• nirmatrelvir and ritonavir
• nitrates (e.g., isosorbide dinitrate, nitroglycerin)
• obinutuzumab
• pentoxifylline
• pergolide
• phenelzine
• phenobarbital
• phenytoin
• phosphodiesterase 5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)
• pramipexole
• primidone
• proton pump inhibitors (e.g., lansoprazole, omeprazole, pantoprazole)
• rasagiline
• rifampin
• roflumilast
• ropinirole
• rotigotine
• sacubitril
• selegiline
• sodium bicarbonate
• spironolactone
• theophyllines (e.g., aminophylline, theophylline)
• tizanidine
• tranylcypromine
• tretinoin
• tricyclic antidepressants (e.g., clomipramine, imipramine)
• tyrosine kinase inhibitors (e.g., ceritinib, idelalisib, tucatinib)

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.