Tadalafil: Uses, Dosage, and Side Effects You Should Know

By selectively inhibiting PDE-5, tadalafil causes nitric oxide–mediated vasodilation in the pulmonary vasculature.

• Do not take Tadalafil 40mg if you are on medications containing nitrates.
• Follow the prescribed dosing schedule strictly for safety and effectiveness.
• The medication may cause a sudden drop in blood pressure in some users.
• Inform your doctor about all health conditions before starting Tadalafil.
• Do not take more than one dose per day to avoid overdose risks.
• Use this medication responsibly to manage ED effectively and safely.

Tadalafil has a greater affinity (10,000-fold) for PDE-5 compared with the other PDE inhibitors and has a t½ of 17.5 hours. In a controlled clinical study in patients with PAH, patients receiving tadalafil in a total daily dose of 40 mg had significant improvements in their 6-minute walk distance (33 m from baseline) and time to clinical worsening compared with those receiving placebo (both, P < 0.05). Tadalafil had adverse effects similar to placebo, with headache being the most commonly reported (42%). In the small number of studies available, tadalafil was effective and well tolerated when used to treat patients with PAH. Compared with placebo, tadalafil was associated with significant improvements in exercise capacity and reduced time to clinical worsening (68% relative risk reduction; P = 0.038).

• Tadalafil 40mg is available in some countries only as a prescription medication.
• Use with caution in patients with retinal disorders or retinitis pigmentosa.
• Be aware of possible side effects like dizziness, visual disturbances, or flushing.
• Do not use this medication if you have recently had a stroke or heart attack.
• Tadalafil 40mg can help improve quality of life for men with ED.
• Always discuss your full medical history with your healthcare provider beforehand.

There is limited evidence comparing tadalafil with sildenafil and vardenafil, and the studies are limited by short treatment durations.

1.1 Pulmonary Arterial Hypertension

The side effect profile was similar to that of sildenafil. Tadalafil is an oral PDE-5 inhibitor with longer half-life than sildenafil so that it requires once daily administration. To date, only one case describing treatment of PoPH has been reported that showed a small improvement in portal venous and pulmonary artery pressures [67]. We believe that the role for tadalafil in the treatment of tadalafil over the counter uk PoPH is similar to that of sildenafil. In a single randomized placebo-controlled study 10 HAPE-susceptible subjects received tadalafil 10 mg twice daily during a rapid ascent to 4559 m [86].

3. Do you take other medications?

Two of the subjects receiving tadalafil withdrew from the study due to severe AMS on arrival at 4559 m, although they did not have HAPE prior to descent. Only 1 of the remaining 8 subjects who received tadalafil developed HAPE. In the placebo group, 7 of 9 subjects developed HAPE. The occurrence of AMS with tadalifil may have discouraged further trials as well as the accumulation of any clinical experience using tadalafil in the prevention of HAPE. Tadalafil cannot be recommended to prevent HAPE in the absence of further study.

Tadalafil strengths

Tadalafil is a selective PDE5-inhibitor that can be administered once daily. Its beneficial effects in adults with PAH, consisting of improved exercise capacity, haemodynamics and time to clinical worsening, have been demonstrated in a recent pivotal RCT (PHIRST-1). Patients were at least 12 years old, however the median age was 54 ± 15 years. Tadalafil was well tolerated, side-effects reported were headache, myalgia and flushing.53 No specific data concerning tadalafil in children with PAH are available. Tadalafil, a carboline derivative with vasodilatory activity, selectively inhibits cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). Tadalafil is a beta-carboline–based PDE5 inhibitor that was designed to inhibit PDE activity and to have high specificity for PDE5.

The selectivity of tadalafil for PDE5 is reported to be 9000-fold to 10,000-fold greater than for PDE1 to PDE4 and PDE7 to PDE1069and package insert and to be nearly 800-fold greater for PDE5 than for PDE6.69 The clinical efficacy of tadalafil as a PDE5 inhibitor has been well shown in studies of ED and seems to be at least as effective as other PDE5 inhibitors.70 Following successful reports of sildenafil for the treatment of PAH, several preliminary studies reported similar efficacy for this indication with tadalafil.

7.3 Antihypertensives

During sexual stimulation, nitric oxide (NO) produced and released from nerves and endothelial cells, stimulates soluble guanylate cyclase and initiates the production of the messenger cGMP in the corpus cavernosum smooth muscles. PDE5 is important in regulating intracellular concentrations of cGMP by catalyzing its hydrolysis and inactivating cGMP. The inhibition of PDE5 by tadalafil increases the cGMP level in the corpus cavernosum. As a result, prolonged smooth muscle relaxation occurs together with vasodilation of the corpus cavernosum, leading to penile erection (Carrier, 2003). Tadalafil has no effect in the absence of sexual stimulation.

Tadalafil for Raynaud’s Phenomenon

In addition, tadalafil is also used to treat benign prostatic hyperplasia (BPH) and pulmonary arterial hypertension (Croxtall and Lyseng-Williamson, 2010). Tadalafil preserves the concentration of cGMP, thus promoting vasodilation in corpus cavernosum and pulmonary vasculature. Tadalafil is rapidly absorbed after oral administration. Compared with other PDE5 inhibitors used in treating erectile dysfunction, tadalafil has the longest duration of action, making it the only once-daily agent of all PDE5 inhibitors. Tadalafil is a phosphodiesterase-5 (PDE-5) inhibitor that was approved by the US Food and Drug Administration (FDA) in 2009 for the treatment of pulmonary arterial hypertension (PAH). The longer half-life of tadalafil, which allowed once-daily dosing, also made it an attractive alternative to sildenafil for the long-term treatment of PAH. In 2004, Ghofrani and colleagues71 compared the acute vasodilator effects of 3 PDE5 inhibitors in 60 consecutive patients as part of their initial evaluation of pulmonary hypertension. Compared with sildenafil and vardenafil, tadalafil produced similar decreases in mPAP and PVR and increases in CI.

The peak vasodilator effect occurred after approximately 45 minutes for vardenafil (10 or 20 mg), 60 minutes for sildenafil (50 mg), and 75 to 90 minutes for tadalafil (20–60 mg).

• Tadalafil 40mg is sometimes used off-label for other medical conditions.
• Keep a record of your medication intake and any side effects.
• Do not share Tadalafil 40mg with others, even if they have similar symptoms.
• Tadalafil 40mg can be part of a comprehensive ED treatment plan.
• Follow prescribed dosing strictly to avoid adverse effects.
• Avoid driving or operating machinery if feeling dizzy after taking Tadalafil 40mg.

In the same year, the first of a few small open-label trials and case reports described the clinical benefits of extended treatment with tadalafil in PAH.72,73 In 2007, 2 small open-label trials in India reported improvement in symptoms and pulmonary hemodynamics in patients with PAH treated with tadalafil.74,75 A large, multicenter, randomized controlled trial of tadalafil called the PHIRST (Pulmonary Arterial Hypertension and Response to Tadalafil) study began to enrolled patients with idiopathic or associated PAH in 2005.76 This pivotal trial randomized 405 patients to placebo, 2.5, 10, 20, or 40 mg of tadalafil once daily.

Estimated Cost of Tadalafil

Combination drug therapy tends to be more expensive than standard generic tablets. Most patients will be better suited to try one drug for a couple of weeks and then switch to the other for another couple of weeks to see which has a better function and side effect profile. From then on, patients can enjoy the low cost of generic tablets while still getting the same benefit. Marketing ED medications and various formulations and options is a billion-dollar business with plenty of misunderstandings that must be corrected. Ultimately, patients should speak to a qualified men’s health urologist to understand more about the cause of their ED and their best treatment options.

The Bottom Line

Newfangled ED medication options like combination therapy may be marketed as effective, but ultimately, they may be a waste of money. We encourage you to contact our office to learn more. Tadalafil is defined as an oral PDE-5 inhibitor that has a longer half-life than sildenafil, allowing for once daily administration. It is used in the treatment of conditions such as pulmonary arterial hypertension, showing small improvements in portal venous and pulmonary artery pressures. Tadalafil is a newer, longer-acting PDE5 inhibitor.

Tadalafil for Pulmonary Arterial Hypertension (PAH)

A recent 16-week RCT included patients with IPAH and PAH associated with connective tissue disease, congenital heart disease, and HIV who were randomized to placebo or tadalafil 2.5 mg, 10 mg, 20 mg, or 40 mg orally once daily.46 Treatment was given as monotherapy, or, in 53% of patients, as add-on therapy to bosentan. Tadalafil 40 mg increased 6-minute walk distance and quality of life, delayed the time to clinical worsening, and improved hemodynamics. The most common treatment-related adverse event reported with tadalafil was headache. Tadalafil is a once daily dispensed, selective PDE-5i. An RCT (PHIRST [Pulmonary arterial Hypertension and ReSponse to Tadalafil] trial) in 406 PAH patients (53% on background bosentan therapy) treated with tadalafil 2.5, 10, 20, or 40 mg once daily has shown favorable results on exercise capacity, symptoms, hemodynamics, and time to clinical worsening at the highest dose (44). Most patients had idiopathic or heritable PAH.

Recent Updates on Tadalafil Research

The purpose of this review is to evaluate the pharmacology, pharmacokinetic properties, clinical efficacy, adverse effects, drug interactions, and dosage and administration of tadalafil in patients with PAH. A literature search tadalafil 10mg daily of MEDLINE and International Pharmaceutical Abstracts (1960 through September 5, 2010) was conducted with the search terms tadalafil, pulmonary arterial hypertension, and phosphodiesterase-5 inhibitor. Data found from orignial research and case series published in English were screened for relevancy to pharmacology, pharmacokinetics, clinical efficacy and safety, and tolerability. Relevant articles from the bibliographies of the identified published articles were also obtained. Unpublished data and posters were obtained from the manufacturer of tadalafil and the FDA Web site. Approximately one-quarter had PAH associated with connective tissue disease, and slightly more than half the patients were taking bosentan at the time of enrollment. Randomization was stratified for baseline 6MWD, type of PAH, and background treatment with bosentan. The primary end point was change from baseline to 16 weeks in 6MWD and was significantly greater for the 10-mg, 20-mg, and 40-mg tadalafil groups than for placebo (P = .047, P = .028, and P<.001), but the prespecified significance level of P<.01 was reached only in the group that received 40 mg of tadalafil (Fig. Time to clinical worsening defined as death, heart or lung transplantation, atrial septostomy, hospitalization for worsening PAH, initiation of a new therapy for PAH, or increase in WHO functional class was longer and the incidence of clinical worsening was less in patient who received 40 mg of tadalafil versus placebo.