What is Macitentan: Uses, Dosage, Side Effects and More

Macitentan is a prescription medication that helps treat pulmonary arterial hypertension (PAH), a serious condition where blood pressure in the arteries of your lungs becomes dangerously high. This oral medication works by blocking certain receptors that cause blood vessels to narrow, helping your heart pump blood more easily through your lungs.

If you or someone you care about has been prescribed macitentan, you probably have questions about how it works and what to expect. Let's walk through everything you need to know about this medication in a way that feels manageable and clear.

What is Macitentan?

Macitentan belongs to a class of medications called endothelin receptor antagonists. Think of it as a key that blocks the locks on certain receptors in your blood vessels that would otherwise cause them to tighten up.

Your body naturally produces a substance called endothelin, which can make blood vessels narrow. In people with PAH, this narrowing happens too much in the lung arteries. Macitentan steps in to prevent this excessive narrowing, allowing blood to flow more freely through your lungs.

This medication is specifically designed for long-term use and represents an important advancement in treating PAH. It's typically prescribed when other treatments haven't provided enough relief or as part of a combination therapy plan.

What is Macitentan Used For?

Macitentan is primarily used to treat pulmonary arterial hypertension, a condition where the small arteries in your lungs become narrow, blocked, or destroyed. This makes it much harder for your heart to pump blood through your lungs.

People with PAH often experience shortness of breath, fatigue, chest pain, and dizziness because their hearts are working overtime to push blood through these narrowed lung arteries. Over time, this extra work can weaken the heart.

Your doctor may prescribe macitentan if you have PAH that's related to various underlying conditions. These can include connective tissue diseases like scleroderma, congenital heart defects, or sometimes PAH that develops without a clear cause.

The medication helps slow the progression of PAH and can improve your ability to exercise and perform daily activities. It's often used alongside other PAH treatments to give you the best possible outcomes.

How Does Macitentan Work?

Macitentan is considered a moderately strong medication that works by blocking endothelin receptors in your blood vessels. When these receptors are blocked, the blood vessels in your lungs can relax and widen, reducing the pressure your heart faces.

The medication specifically targets two types of endothelin receptors, called ETA and ETB receptors. By blocking both types, macitentan provides more comprehensive protection against blood vessel narrowing than some older medications in this class.

You'll typically start to notice improvements in your symptoms within a few weeks to months of starting treatment. However, the full benefits may take several months to become apparent as your cardiovascular system adjusts to the improved blood flow.

This medication works best as part of a long-term treatment plan. It's not a quick fix, but rather a steady support system that helps maintain better blood flow through your lungs over time.

How Should I Take Macitentan?

Take macitentan exactly as your doctor prescribes, usually once daily with or without food. The tablet can be taken with water, and you don't need to worry about timing it with meals since food doesn't significantly affect how your body absorbs the medication.

It's best to take your dose at the same time each day to help you remember and maintain steady levels of the medication in your system. Many people find it helpful to link taking their medication to a daily routine, like brushing their teeth or having breakfast.

Swallow the tablet whole with water. Don't crush, chew, or break the tablet, as this can affect how the medication is released in your body.

If you're taking other medications for PAH, your doctor will coordinate the timing to ensure they work well together. Always follow your healthcare provider's specific instructions, as they may adjust your routine based on your individual needs.

How Long Should I Take Macitentan For?

Macitentan is typically prescribed as a long-term treatment, often for years or even indefinitely. PAH is a chronic condition that requires ongoing management, and stopping the medication abruptly can cause your symptoms to return or worsen.

Your doctor will monitor your response to the medication through regular check-ups, blood tests, and heart function assessments. Based on how you're doing, they may adjust your treatment plan over time.

Some people take macitentan for many years with good results, while others may need to switch to different medications or add additional treatments. The key is working closely with your healthcare team to find what works best for your specific situation.

Never stop taking macitentan suddenly without talking to your doctor first. If you need to discontinue the medication, your doctor will create a plan to do so safely, possibly by gradually reducing your dose or switching to an alternative treatment.

What Are the Side Effects of Macitentan?

Like all medications, macitentan can cause side effects, though not everyone experiences them. Most side effects are manageable, and many people find that any initial discomfort improves as their body adjusts to the medication.

The most common side effects you might experience include headache, swelling in your legs or ankles, and upper respiratory tract infections. These occur in a significant number of people but are usually mild to moderate in severity.

Here are the more frequently reported side effects to be aware of:

• Headache (often improves after the first few weeks)
• Swelling in legs, ankles, or feet
• Upper respiratory infections like cold symptoms
• Stuffy or runny nose
• Bronchitis
• Urinary tract infections

Most of these side effects are temporary and become less bothersome as your body adapts to the medication. Your doctor can suggest ways to manage any uncomfortable symptoms you experience.

There are also some serious but less common side effects that require immediate medical attention. While these are rare, it's important to know what to watch for so you can get help quickly if needed.

Contact your doctor right away if you experience any of these more serious symptoms:

• Significant decrease in red blood cells (anemia), which might cause unusual fatigue or weakness
• Liver problems, including yellowing of skin or eyes, dark urine, or persistent nausea
• Sudden severe swelling of face, lips, tongue, or throat
• Difficulty breathing or swallowing
• Unusual bleeding or bruising

These serious side effects are uncommon, but recognizing them early can help ensure you get the care you need promptly. Your doctor will monitor you regularly to catch any potential issues before they become serious.

Who Should Not Take Macitentan?

Macitentan isn't suitable for everyone, and there are certain situations where your doctor will recommend a different treatment approach. The most important restriction is for people who are pregnant or might become pregnant.

If you're pregnant or planning to become pregnant, you should not take macitentan because it can cause serious birth defects. Women of childbearing age need to use reliable contraception while taking this medication and for at least one month after stopping it.

Your doctor will also be cautious about prescribing macitentan if you have certain medical conditions. These situations require careful consideration and close monitoring:

• Severe liver disease or liver function problems
• Severe kidney disease
• Low blood pressure that causes symptoms
• Certain types of heart problems
• Severe anemia or other blood disorders

Additionally, if you've had allergic reactions to macitentan or similar medications in the past, your doctor will likely choose a different treatment option for you.

Age can also be a factor in treatment decisions. While macitentan can be used in older adults, your doctor may start with a lower dose or monitor you more closely if you're over 65 or have multiple health conditions.

Macitentan Brand Names

Macitentan is available under the brand name Opsumit in most countries, including the United States. This is the most commonly prescribed formulation you'll encounter at pharmacies.

The medication is manufactured by Actelion Pharmaceuticals, and Opsumit is currently the primary brand name used worldwide. You might occasionally see it referred to by its generic name, macitentan, especially in medical literature or when discussing treatment options.

When you pick up your prescription, the label will likely show "Opsumit" as the brand name, with "macitentan" listed as the generic or active ingredient name. Both names refer to the same medication.

It's worth noting that generic versions of macitentan may become available in the future, but currently, Opsumit is the main option prescribed by doctors for this particular medication.

Macitentan Alternatives

If macitentan isn't the right fit for you, there are several other medications that can effectively treat PAH. Your doctor might consider these alternatives based on your specific symptoms, other health conditions, and how you respond to treatment.

Other endothelin receptor antagonists work similarly to macitentan but may have different side effect profiles. These include bosentan (Tracleer) and ambrisentan (Letairis), which have been used successfully for many years.

Beyond endothelin receptor antagonists, there are other classes of PAH medications that work through different mechanisms:

• Phosphodiesterase-5 inhibitors like sildenafil (Revatio) and tadalafil (Adcirca)
• Prostacyclin analogs such as epoprostenol (Flolan) and iloprost (Ventavis)
• Soluble guanylate cyclase stimulators like riociguat (Adempas)
• Prostacyclin receptor agonists such as selexipag (Uptravi)

Many people with PAH actually take combinations of these medications to get the best results. Your doctor might start with one medication and add others over time, or they might recommend starting with a combination right away.

The choice of alternative depends on many factors, including your overall health, other medications you're taking, and your personal preferences about things like how often you need to take medication or potential side effects.

Is Macitentan Better Than Bosentan?

Both macitentan and bosentan are endothelin receptor antagonists that treat PAH effectively, but they have some important differences that might make one more suitable for you than the other.

Macitentan is generally considered to have some advantages over bosentan. It tends to cause fewer liver problems, which means you may need less frequent blood testing to monitor your liver function. This can make treatment more convenient and less worrying.

Studies have shown that macitentan may also be more effective at preventing PAH from getting worse over time. In clinical trials, people taking macitentan had fewer hospitalizations and disease progression events compared to those taking placebo.

However, bosentan has been used for longer and has a well-established track record of safety and effectiveness. Some people do very well on bosentan and don't need to switch to newer medications.

The choice between these medications often comes down to individual factors like your liver function, other health conditions, and how you respond to treatment. Your doctor will consider your complete medical picture when recommending the best option for you.