Cialis interactions and side effects

Tadalafil is metabolised by cytochrome CYP3A4 and its toxicity may be increased in patients undergoing therapy with other substrates or inhibitors of this enzyme, such as macrolide and imidazole antibiotics, statins, antiretroviral drugs.Caution  is

advised when prescribing 시알리스 구매 to patients who are using potent CYP3A4 inhibitors (ritonavir, saquinavir, ketoconazole, itraconazole, grapefruit juice, clarithromycin and erythromycin) as increased exposure to tadalafil has been observed when the medicines are given in combination.

A CYP3A4 inducer, such as rifampicin, reduced the distribution of tadalafil by 90%, possibly reducing its efficacy. Other CYP3A4 inducers, such as phenobarbital, phenytoin and carbamazepine, may decrease the plasma concentrations of tadalafil. 

Tadalafil does not inhibit or induce CYP450 isoenzymes, including CYP3A4, CYP1A2, CYP2D6, CYP2E1, CYP2C9 and CYP2C19.

The role of protein carriers (such as, for example, p-glycoprotein) in the distribution of tadalafil has not been fully investigated. Therefore, the possibility exists of a drug interaction mediated by the inhibition of transporters.

The safety and efficacy of combining tadalafil with other PDE5 inhibitors or other treatments for erectile dysfunction have not been studied. Patients should be advised not to take 시알리스 구매 in combination with such medicines.

Type 5 phosphodiesterase inhibitors can also prolong cardiac repolarization.

Interactions with other hypotensive drugs

The possible interactions between tadalafil and major classes of antihypertensive medicinal products , including calcium channel blockers (amlodipine), angiotensin converting enzyme (ACE) inhibitors (enalapril), beta-adrenergic receptor blockers (metoprolol) were investigated. , thiazide diuretics (bendrofluazide) and angiotensin II antagonists (various types and at various dosages, alone or in combination with thiazides, calcium channel blockers, beta-blockers and / or alpha-blockers). Tadalafil (10 mg, except for studies with angiotensin II antagonists and amlodipine where a dose of 20 mg was used) had no clinically significant interaction with any of these classes. 

Tadalafil (20 mg) has been studied in combination with 4 classes of antihypertensives . In subjects taking multiple antihypertensives, changes in outpatient controlled blood pressure appeared to be related to the degree of blood pressure control. In people with well- controlled blood pressure , the reduction in blood pressure was minimal and similar to that seen in healthy subjects. In study subjects with uncontrolled blood pressure, the reduction was greater without hypotensive symptoms. Thus, in patients receiving concomitant antihypertensive medicinal products, 20 mg of tadalafil may induce a reduction in blood pressure, which (with the exception of alpha blockers - see doxazosin above) is generally minor and probably not clinically relevant. 

Other possible interactions

In a clinical study comparing tadalafil 5 mg co-administered with finasteride 5 mg in the treatment of symptoms of benign prostatic hyperplasia , no new adverse reactions were identified. However, as a formal drug interaction study evaluating the effects of tadalafil and 5-alpha reductase inhibitors (5-ARIs) has not been performed , tadalafil should be used with caution when co-administered with 5-alpha reductase inhibitors. .

After co-administration of 10 mg of 시알리스 구매 tadalafil together with theophylline (a substrate of CYP1A2 and a non-selective phosphodiesterase inhibitor), no pharmacokinetic interactions occurred apart from a small increase (3.5 bpm) in heart rate . Although this effect is minor, and has not been of any clinical relevance, it should be considered when these medicinal products are administered concurrently.

Tadalafil increases the oral bioavailability of ethinylestradiol, although the clinical consequence is still uncertain.

An increaseAUC and Cmax similar to that observed with ethinylestradiol can be expected with oral administration of terbutaline, possibly due to inhibition of intestinal sulfation by tadalafil . The clinical relevance of this finding is uncertain. Tadalafil (20 mg) did not increase the mean alcohol-induced decrease in blood pressure (0.7 g / kg or approximately 180 ml of 40% alcohol [vodka] in an 80 kg man), but in some subjects postural dizziness and orthostatic hypotension were observed.

Side effects

Side effects of type 5 phosphodiesterase inhibitors include: headache, flushing of the face, rhinitis, dyspepsia due to relaxation of the esophageal sphincter, back pain, nasal congestion, myalgia, pain in the extremities, with an incidence that is dose-dependent (increases with increasing dosage). Episodes of chest pain, peripheral edema, fatigue, haematuria (blood in the urine), abdominal pain, vomiting, nausea, gastroesophageal reflux, hypotension, hypertension, tachycardia, palpitations, tinnitus (the perception of a constant noise in the ear in the absence of an external sound source), blurred vision, dizziness , hypersensitivity reactions. 

The reactions adverse events are generally transient , and generally mild or moderate . The largest number of headache cases reported with tadalafil administered once daily occurred within the first 10-30 days of starting treatment.

Tadalafil can also weakly inhibit phosphodiesterase type 6 (PDE6; 700 times less potent on PDE6 than PDE5) which is an enzyme involved in photoreceptor signal translation and thus visual disturbances such as changing color perception can be observed. Unilateral hearing loss is also possible.

In some studies, ECG alteration, particularly sinus bradycardia, not associated with adverse reactions , was reported .