Pulmonary hypertension is a form of high blood pressure affecting the arteries in the lungs and the right side of the heart. In this condition, the blood vessels in the lungs narrow, making it difficult for the heart to pump blood through them. This increased pressure reduces the amount of oxygen in the blood, makes physical activity challenging, and can weaken the heart muscle over time.
One of the primary medications used to manage this condition is tadalafil. While many recognize tadalafil for treating erectile dysfunction as Cialis, its role in pulmonary hypertension is distinct. For this purpose, it is prescribed under the brand name Adcirca to improve symptoms and patient quality of life.
How Tadalafil Treats Pulmonary Hypertension
Tadalafil is part of a class of medications known as phosphodiesterase type 5 (PDE5) inhibitors. These inhibitors work by blocking the action of the PDE5 enzyme, which is found in the smooth muscle cells of blood vessels, including those within the lungs. By inhibiting this enzyme, tadalafil allows for the accumulation of a substance called cyclic guanosine monophosphate (cGMP).
Increased levels of cGMP act as a signaling molecule that causes the smooth muscles in the artery walls to relax and widen, a process called vasodilation. This widening of the vessels lowers the resistance to blood flow. Consequently, the blood pressure within the lungs decreases, which alleviates the workload on the right side of the heart.
This mechanism leads to tangible improvements for the patient. Clinical trials have shown that patients taking tadalafil for pulmonary hypertension experience enhanced exercise capacity. By reducing the strain on the heart and improving blood flow, individuals can be more active with less breathlessness, leading to a better quality of life.
The medication is approved to treat World Health Organization (WHO) functional class II and III pulmonary arterial hypertension (PAH). This indicates its use for patients who have slight to marked limitations in physical activity due to their condition.
Dosage and Administration
The standard dosage of tadalafil for pulmonary hypertension in adults is 40 mg, administered as two 20 mg tablets taken together once a day. It is important for patients to take both tablets at the same time to provide a consistent level of the medication in the body.
Patients can take tadalafil with or without food. A healthcare provider may prescribe a lower starting dose to allow the body to adjust before increasing to the full 40 mg dose. Individuals should follow the specific directions provided by their healthcare provider.
If a dose is missed, it should be taken as soon as it is remembered. However, if it is almost time for the next scheduled dose, the missed dose should be skipped. Do not take a double dose to make up for a missed one, as this can increase the risk of side effects.
Patients should not stop taking tadalafil without first consulting their healthcare professional, as abruptly discontinuing the medication could cause their condition to worsen. The dosage may be adjusted by a doctor based on the patient’s response and tolerance. Regular follow-ups are a standard part of the treatment plan.
Potential Side Effects
When taking tadalafil for pulmonary hypertension, patients may experience side effects, most of which are mild to moderate and often occur as the body adjusts to the drug. The most commonly reported side effects include:
- Headaches
- Muscle aches (myalgia)
- Flushing of the face
- Indigestion
- A stuffy or runny nose
- Pain in the arms, legs, and back
While many side effects are not severe, several serious adverse effects require immediate medical attention. One is a sudden loss of vision in one or both eyes, which can be a sign of a serious eye problem known as non-arteritic anterior ischemic optic neuropathy (NAION). Another is sudden hearing loss, which may be accompanied by dizziness or ringing in the ears (tinnitus).
Chest pain, particularly if it occurs after starting the medication, should be reported to a doctor right away. For male patients, an erection that is painful or lasts for more than four hours, a condition called priapism, is a rare but serious side effect. If not treated promptly, priapism can cause permanent damage.
Symptoms of a severe allergic reaction are also a cause for immediate medical help, including swelling of the face, lips, or tongue, difficulty breathing, or an itchy rash. Any of these more severe reactions warrant stopping the medication and seeking emergency medical care.
Important Safety Considerations
A primary safety warning for tadalafil involves its interaction with nitrate medications. Tadalafil must not be taken with any form of nitrate, which is often prescribed for chest pain (angina), such as nitroglycerin. The combination can cause a sudden and severe drop in systemic blood pressure, potentially leading to fainting or loss of consciousness. Nitrates should be avoided for at least 48 hours after the last dose.
Caution is also advised when tadalafil is used with other blood pressure-lowering medications, including alpha-blockers. While tadalafil primarily targets the lung’s arteries, it has a mild effect on overall body blood pressure. Combining it with other antihypertensive drugs can amplify this effect, so careful monitoring by a healthcare provider is needed to prevent hypotension.
Certain pre-existing medical conditions may increase the risks associated with tadalafil use. Individuals with a history of heart attack or stroke, severe liver or kidney disease, or certain degenerative eye conditions should use this medication with caution. Patients with low systemic blood pressure (hypotension) or dehydration should also be carefully evaluated before starting treatment.
Before beginning treatment, it is important that patients provide their doctor with a complete medical history and a full list of all medications they are taking, including over-the-counter drugs and supplements. This allows the healthcare provider to assess potential drug interactions and contraindications, ensuring the safe use of tadalafil.