Tadalafil (Cialis): leaflet, how to take, contraindications and side effects.

What is tadalafil?

Tadalafil is an active ingredient belonging to the class of phosphodiesterase type 5 (PDE-5) inhibitors. It is a synthetic substance used in the treatment of erectile dysfunction, also known as male sexual impotence, and in the treatment of signs and symptoms of benign prostatic hyperplasia (BPH).

What is it for?

Erection at dosages of 10mg and 20mg: Tadalafil is prescribed to help men who have difficulty getting or maintaining an erection sufficient for sexual activity. It is used to treat erectile dysfunction by improving the penis's responsiveness to sexual stimuli.

Prostate and erection at a dosage of 5mg: It helps to relieve urinary symptoms related to this condition, such as difficulty and frequent urge to urinate and post-micturition dribbling. It also improves sexual performance. 

How does tadalafil work (pharmacodynamics and pharmacokinetics)?

For tadalafil to produce effective results, sexual stimulation is essential. Simply taking a tadalafil tablet will not result in an automatic erection.

Tadalafil acts selectively by inhibiting the enzyme phosphodiesterase type 5 (PDE-5), present in the smooth muscle tissue of the penis. By blocking this enzyme, tadalafil allows nitric oxide (NO) released during sexual stimulation to remain in the penis for longer. Nitric oxide is responsible for activating an enzyme called guanylate cyclase, which increases levels of cyclic guanosine monophosphate (cGMP). This substance promotes the relaxation of smooth muscles and vasodilation of blood vessels in the penis, facilitating blood flow and promoting erection.

Tadalafil also works in the treatment of Benign Prostatic Hyperplasia (BPH) by relaxing the muscles of the prostate, bladder and blood vessels, increasing blood flow to the prostate and bladder, reducing the symptoms of BPH. In addition, relaxing the muscles of the prostate and bladder complements these vascular effects, leading to normalization of the urethra and improved urination.

It is rapidly absorbed by the body. It begins to take effect about 30 minutes after taking it, its maximum plasma concentration is reached in about 2 hours, and it has a long elimination half-life of approximately 17.5 hours, which means that its effect can last up to 36 hours. 

1. Tadalafil 5 mg: It is a lower dose option and is often recommended for daily use, regardless of sexual activity. This dose is appropriate for both ongoing treatment of erectile dysfunction and is best suited for treating benign prostatic hyperplasia (BPH). Although its effect is milder, it is still effective in achieving and maintaining erections.

2. Tadalafil 10 mg: It is an intermediate dosage. It is generally recommended for use before sexual activity and is suitable for people who do not need the medication daily but want a quick response before occasional sexual intercourse. It provides fewer side effects compared to 20 mg and a more intense effect compared to 5 mg, helping to obtain stronger and longer-lasting erections.

3. Tadalafil 20 mg: is the maximum recommended dosage and may be more potent in terms of results, but may have more side effects. It may be more effective for people with more severe erectile dysfunction, providing firm and sustained erections for a longer period.

How to take?

To use tadalafil correctly, simply take it at least 30 minutes before sexual intercourse, take it orally with water and swallow it whole, without worrying about whether it is before or after meals.

This medicine should not be broken, opened or chewed and the maximum recommended daily dose of tadalafil is 20 mg and the effects last for an average of 36 hours.

Contraindications and warnings

• It should not be used by men without erectile dysfunction.
• It should not be consumed by those allergic to tadalafil or any component of the composition.
• It is not recommended for use in people who are taking medications containing nitrates, such as propatilnitrate, isosorbide, nitroglycerin and isosorbitol dinitrate.
• Not suitable for women.

• It should be used with caution in patients with heart problems, uncontrolled high or low blood pressure, history of stroke, liver problems, kidney problems, stomach ulcers, bleeding problems, deformity of the penis, or Peyronie's disease.
• Patients with conditions that may predispose to priapism (painful erection lasting more than four hours), such as sickle cell anemia, multiple myeloma, or leukemia, should take the drug with caution.
• It is recommended to avoid consumption in conjunction with sexual activity in patients with serious heart disease.
• It is not advisable to use tadalafil simultaneously with other phosphodiesterase 5 (PDE5) inhibitors or treatments for erectile dysfunction.
• The combination of tadalafil with drugs that stimulate the enzyme guanylate cyclase, such as Riociguat, is not recommended due to the risk of symptomatic hypotension (decrease in blood pressure).
• There have been a few rare cases of vision loss associated with the use of erectile dysfunction medications, including tadalafil. People with diabetes, high blood pressure, high cholesterol, heart disease, and smokers are at higher risk of developing this condition. If you experience a change in vision during treatment, it is important to stop taking the medication and seek medical attention.
• In case of sudden decrease or loss of hearing, discontinue use and seek medical advice. These events have been reported in temporal association with the use of PDE5 inhibitors, but it is not known whether they are directly related to the drug.
• You should tell your doctor about all medications you are taking, including non-prescription medications, especially those used for heart problems, high blood pressure, prostate problems, antibiotics, medications for treating HIV/AIDS, antifungal medications, and medications for stomach diseases such as gastritis and ulcers.

Side effects

Tadalafil can cause some side effects. Here are the main ones:

Very common effects (in more than 10% of patients):

• Headache (cephalalgia).

Common effects (between 1% and 10% patients):

• Facial redness (facial flushing)
• Back pain
• Dizziness
• Stomach upset (dyspepsia)
• Muscle pain (myalgia)
• Nasal congestion
• Diarrhea in elderly patients over 65 years of age
• Nausea
• Tiredness

Uncommon effects (between 0.1% and 1% of patients):

• Redness in the eyes (conjunctival hyperemia)
• Feeling of pain in the eyes
• Swelling of the eyelids
• Shortness of breath (dyspnea)
• Vomiting
• Swelling in the legs, feet and hands (peripheral edema).

Very rare adverse events (occur in less than 0.01% of patients):

• Hypersensitivity reactions such as skin rash, itching (hives), facial swelling
• Stevens-Johnson syndrome (severe skin inflammation with blistering)
• Exfoliative dermatitis (inflammation of the skin with widespread scaling)

Other very rare reported adverse events:

• Serious cardiovascular events such as myocardial infarction, sudden cardiac death, stroke, chest pain, palpitations and tachycardia (fast heartbeat)
• Hypotension (decreased blood pressure)
• Hypertension (increased blood pressure)
• Fainting (syncope)
• Abdominal pain
• Gastroesophageal reflux
• Profuse sweating (hyperhidrosis)
• Blurred vision
• Nonarteritic anterior ischemic optic neuropathy (interruption of blood flow to the optic nerve) with possible decreased vision
• Retinal vein occlusion (obstruction)
• Change in visual field
• Priapism (painful erection lasting more than 4 hours)
• Migraine
• Nosebleed (epistaxis)
• Sudden decrease or loss of hearing

In case of unusual side effects, it is important to notify the drug manufacturer and also register the incident in the Adverse Drug Event Reporting System – Vigimed. You can access it through the website: http://portal.anvisa.gov.br/vigimed.

Composition: 

The composition of tadalafil varies depending on the manufacturer, but generally includes:

• Concentrations of 5 mg, 10 mg or 20 mg;
• Main active substance is tadalafil;
• Secondary substances: purified water, hyprolose, lactose monohydrate, croscarmellose sodium, sodium lauryl sulfate, povidone, methylene chloride, methyl alcohol, silicon dioxide, magnesium stearate, hypromellose/titanium dioxide/macrogol/talc/yellow iron oxide.

It is important to carefully read the leaflet of the specific medicine you are using to check the composition and excipients present, as there may be variations.

Technical information:

• Molecular formula: C₂₂H₁₉N₃O₄
• Half-life: 17.5 hours
• Administration: Oral
• CAS: 171596-29-5
• Metabolism: P450 (CYP) isoform 3A4
• Law: Generic Drug Law No. 9,787, of 1999

Trade names for Tadalafil

Some of the commercial names for this medicine generally sold in Brazil are:

• Cialis;
• Generic Tadalafil;
• Adcirca;
• Bontalis;
• Cyanide;
• Ciavor;
• From there;
• H-For;
• Hislafi;
• Tada;
• Tadifil;
• Talix;
• Tonifille;
• Vorallis;
• Zyad;

Interactions with other medications

• Tadalafil does not significantly affect the metabolism of other drugs in the body.
• Use of ketoconazole may increase exposure to Tadalafil.
• Ritonavir may also increase exposure to Tadalafil.
• Use of rifampin may reduce exposure to Tadalafil.
• Tadalafil may potentiate the hypotensive effects of antihypertensive agents.
• When combined with alpha-adrenergic blockers, Tadalafil may cause a drop in blood pressure and symptoms such as syncope.
• Alcohol consumption in low doses does not affect Tadalafil, but in high doses it can cause dizziness and hypotension.
• Antacids and H2 antagonists have no significant effect on the absorption of Tadalafil.
• Tadalafil does not interfere with the action of Aspirin® on bleeding time.
• Tadalafil does not affect the effectiveness of warfarin on prothrombin time.
• Tadalafil does not interfere with the pharmacokinetics or pharmacodynamics of theophylline.
• There are no studies on interactions with medicinal plants, nicotine and laboratory tests.

It is important to inform your doctor of all medications you are taking, as some may interact with Tadalafil, affecting its effectiveness or causing unwanted side effects.

Overdose: what happens if you take more than recommended?

Side effects caused by excessive doses were similar to those seen with lower doses.

If you take too much medication, seek medical help quickly and take the medicine packaging or leaflet with you, if possible. For further guidance, you can also call 0800 722 6001.

Download the original leaflet

Click the button below and download the complete 5mg or 20mg package insert from the Manufacturers:

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Sources and bibliography:

This article was manually extracted from the original package insert of the medicines produced by Teuto® 20mg and Aché® 5mg in June 2022, under technical supervision of the responsible pharmacist.

To access the tadalafil leaflet, you can visit the ANVISA electronic leaflet and search for the manufacturer of your choice.

– European Medicines Agency. Features of the drug Cialis.
– ICAQF. Evaluation of the efficacy of tadalafil.
– Sildenafil: Pharmaco-Cinétique. BIAM.
– Cialis: Dangers, Precautions, Pregnancy, Nursing, Abuse. RxList.