- What is tadalafil, and how does it work (mechanism of action)?
- What are the uses for tadalafil?
- What are the side effects of tadalafil?
- What is the dosage for tadalafil?
- Which drugs or supplements interact with tadalafil?
- Is tadalafil safe to take if I'm pregnant or breastfeeding?
- What else should I know about tadalafil?
What is tadalafil, and how does it work (mechanism of action)?
Tadalafil is an oral drug that is used for treating impotence (the inability to attain or maintain a penile erection) and benign prostatic hyperplasia (BPH). It is in a class of drugs called phosphodiesterase-5 (PDE5) inhibitors that also includes sildenafil (Viagra) and vardenafil (Levitra). Erection of the penis is caused by the filling of the penis with blood. Filling occurs because the blood vessels that bring blood to the penis increase in size and deliver more blood to the penis, and, at the same time, the blood vessels that take blood away from the penis decrease in size and remove less blood from the penis. Sexual stimulation that leads to an erection causes the production and release of nitric oxide in the penis. The nitric oxide causes an enzyme, guanylate cyclase, to produce cyclic guanosine monophosphate (cGMP). It is cGMP that is primarily responsible for increasing and decreasing the size of blood vessels carrying blood to and from the penis, respectively, and causing an erection. When the cGMP is destroyed by another enzyme, phosphodiesterase-5, the blood vessels return to their normal size, blood leaves the penis, and the erection ends. Tadalafil prevents phosphodiesterase-5 from destroying cGMP so that cGMP stays around longer. The persistence of cGMP leads to a more prolonged engorgement of the penis with blood.
The mechanism whereby tadalafil improves the symptoms of BPH is not clear, but phosphodiesterase-5 also is present in the muscles of the bladder and the prostate, and it has been suggested that the relaxation of these muscles may make the passage of urine less difficult, for example, by reducing the pressure in the muscle surrounding the opening to the urethra that controls the flow of urine from the bladder. Tadalafil was approved by the FDA in November 2003.
What brand names are available for tadalafil?
Is tadalafil available as a generic drug?
GENERIC AVAILABLE: No
Do I need a prescription for tadalafil?
What are the uses for tadalafil?
What is the dosage for tadalafil?
For most individuals, the recommended starting dose of tadalafil is 10 mg per day taken before sexual activity (tadalafil for use as needed). Depending on the adequacy of the response or side effects, the dose may be increased to 20 mg or decreased to 5 mg a day. The effect of tadalafil may last up to 36 hours. Individuals who are taking medications that increase the blood levels of tadalafil should not exceed a total dose of 10 mg in 72 hours (See drug interactions). For once daily use without regard to sexual activity the recommended dose is 2.5 to 5 mg daily. Tadalafil should not be taken more than once daily.
The recommended dose for BPH, or BPH and ED is 5 mg daily taken about the same time each day. Tadalafil may be taken with or without food since food does not affect its absorption from the intestine.
The dose of tadalafil may require adjustment for patients with reduced kidney or liver function.
Which drugs or supplements interact with tadalafil?
The breakdown and elimination of tadalafil from the body may be decreased by erythromycin, ketoconazole (Nizoral), itraconazole (Sporanox), indinavir (Crixivan) and ritonavir (Norvir). Therefore, these drugs may increase the levels of tadalafil in the blood. If these drugs are being used at the same time as tadalafil, the dose of tadalafil should be reduced to 10 mg every 72 hours when used as needed or 2.5 mg when used daily in order to avoid side effects from high levels of tadalafil.
Rifampin, carbamazepine (Tegretol, Tegretol XR, Equerto, Carbatrol), phenytoin (Dilantin, Dilantin-125), and phenobarbital may decrease blood levels of tadalafil, possibly reducing the effect of tadalafil.
Tadalafil exaggerates the increases in heart rate and lowering of blood pressure caused by nitrates, for example, nitroglycerin, isosorbide dinitrate (Isordil), isosorbide mononitrate (Imdur, Ismo, Monoket), nitroglycerin (Nitro-Dur, Transderm-Nitro) that are used primarily for treating heart pain (angina). In patients who take nitrates for angina, tadalafil could cause heart pain or possibly even a heart attack by exaggerating the increase in heart rate and the lowering of blood pressure. Therefore, tadalafil should not be used with nitrates.
Tadalafil also exaggerates the blood pressure lowering effects of some alpha-blocking drugs for example, terazosin (Hytrin) that primarily are used for treating high blood pressure or enlargement of the prostate (BPH). Individuals who take these alpha-blockers should be on a stable dose of the alpha-blocker before tadalafil is started. In such situations, tadalafil should be started at the lowest dose. If the patient is already taking tadalafil, the alpha-blocker should be started at the lowest dose. Combining tadalafil with alpha-blockers for treatment of BPH is not recommended.
PDE5 inhibitors may affect platelet function and therefore prolong bleeding. Tadalafil should be used cautiously in patients with bleeding disorders or active ulcers. Tadalafil should not be combined with Adcirca (another form of tadalafil) or other PDE5 inhibitors, for example, vardenafil (Levitra) or sildenafil (Viagra, Revatio).
Is tadalafil safe to take if I'm pregnant or breastfeeding?
Tadalafil is not approved for use in women.
Tadalafil is not approved for women and has not been evaluated in women who are breastfeeding.
Tadalafil (Cialis, Adcirca) is a medication prescribed for the treatment of impotence (erectile dysfunction, ED) in men. Review side effects, drug interactions, warnings and precautions, and patient safety information prior to taking any medication.
Multimedia: Slideshows, Images & Quizzes
Erectile Dysfunction (ED) Causes and Treatment
Having erection problems? What is erectile dysfunction (ED)? Learn about erectile dysfunction causes and treatments such as drugs...
Healthy Aging: Better Sex After 50
It's never too late to improve your sex life. Learn how older adults can overcome common health conditions affecting seniors over...
Sex Quiz: Love & Relationships Facts
Relationships, sex, and love! Could it be that what motivates physical attraction in us may be all in our minds? Take the Sex &...
Erectile Dysfunction (Impotence) Quiz: Causes & Treatment
Did you know that certain medical condition may be responsible for ED? Some causes of impotence are medically treatable and...
Picture of Penis
The penis is the male sex organ, reaching its full size during puberty. See a picture of the Penis and learn more about the...
Related Disease Conditions
Sexual Problems in Men
Male sexual dysfunction can be caused by physical or psychological problems. Common sexual problems in men include erectile dysfunction (impotence or ED), premature ejaculation, and loss of libido. Treatment for sexual dysfunction in men may involve medication, hormone therapy, psychological therapy, and the use of mechanical aids.
Erectile Dysfunction (ED, Impotence)
Erectile dysfunction (ED, impotence) is the failure to achieve or maintain an erection. There are many potential underlying causes of erectile dysfunction, including stress and emotional problems, brain dysfunction, problems with blood supply to the penis, and structural problems with the penis.
Scleroderma is an autoimmune disease of the connective tissue. It is characterized by the formation of scar tissue (fibrosis) in the skin and organs of the body, leading to thickness and firmness of involved areas. Scleroderma is also referred to as systemic sclerosis, and the cause is unknown. Treatment of scleroderma is directed toward the individual features that are most troubling to the patient.
Peyronie's Disease (Curvature of the Penis)
Peyronie's disease or curvature of the penis (Peyronie disease) is a condition in which scar tissue develops inside the penis. This scar tissue causes the penis to develop an abnormal curvature in the scarred area. At this time, there is no known cause of Peyronie's disease. Symptoms of Peyronie's disease include pain during intercourse or ejaculation, erectile dysfunction (ED, impotence), the inability to have sexual intercourse, anxiety, stress, an indentation of the shaft at the site where there is plaque or scarring, and an angulation of the penis when erect or flaccid. There is no cure for Peyronie's disease, however, there are medications that can reduce symptoms of the disease. Surgery or penile implants may be an option for severe cases.
Multiple Sclerosis (MS) Symptoms and Treatments
Multiple sclerosis (MS) symptoms vary from person to person and can last for days to months without periods of remission. Symptoms of MS include sexual problems and problems with the bowel, bladder, eyes, muscles, speech, swallowing, brain, and nervous system. The early symptoms and signs of multiple sclerosis usually start between ages 20-40. MS in children, teens, and those over age 40 is rare. Treatment options for multiple sclerosis vary depending on the type and severity of symptoms. Medications may be prescribed to manage MS symptoms.
What Is Diabetic Neuropathy?
Diabetic neuropathy a condition in which nerve damage has occurred as a complication of diabetes. The pain from the nerve damage can be severe with tingling or numbness in the part of the body affected. Diabetic neuropathy can occur anywhere in the body. Diabetic neuropathy can cause symptoms like intense pain, numbness, burning, or tingling in the part of the body affected by the condition. There are four types of neuropathy include peripheral, autonomic, proximal and focal. Natural therapies and medications may help relieve the pain and other symptoms of diabetic neuropathy.
Pulmonary hypertension is elevated pressure in the pulmonary arteries that carry blood from the lungs to the heart. The most common symptoms are fatigue and difficulty breathing. If the condition goes undiagnosed, more severe symptoms may occur. As pulmonary hypertension worsens, some people with the condition have difficulty performing any activities that require physical exertion. While there is no cure for pulmonary hypertension, it can be managed and treated with medications and supplemental oxygen to increase blood oxygen levels.
Heart Attack Treatment
A heart attack involves damage or death of part of the heart muscle due to a blood clot. The aim of heart attack treatment is to prevent or stop this damage to the heart muscle. Heart attack treatments included medications, procedures, and surgeries to protect the heart muscle against injury.
Men's health is an important component to a happy lifestyle and healthy relationships. Eating healthy, exercise, managing stress, and knowing when to have medical tests for a particular age is key to disease prevention in men.
Sexual health information including birth control, impotence, herpes, sexually transmitted diseases, staying healthy, women's sexual health concerns, and men's sexual health concerns. Learn about the most common sexual conditions affecting men and women.
Treatment & Diagnosis
- Sex & Love FAQs
- Impotence Erectile Dysfunction FAQs
- 8 Natural Remedies for Erectile Dysfunction (ED)
- Drugs: The Most Common Medication Errors
- Medication Disposal
- Dangers of Mixing Medications
- Erectile Dysfunction Drugs: Drug Interactions
- Drugs: Buying Prescription Drugs Online Safely
- Things You Should Know About the Penis
- Generic Drugs, Are They as Good as Brand-Names?
Medications & Supplements
Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.