Commonly Identified Brand -
Cialis
MOA
This
Prescription (Rx) drug is a phosphodiesterase enzyme (PDE5) inhibitor.
This enzyme is
responsible for the degradation cyclic guanosine monophosphate (cGMP) produced in
reaction to sexual stimulation. The more cGMP is available, the more durable the
erection. It inhibits the PDE5 enzyme, preserving cGMP levels, therefore
aiding erection viability and durability 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 the cGMP that is primarily
responsible for increasing and decreasing the size of the blood vessels carrying
blood to and from the penis, respectively, and causing the 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. It 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. It relaxes
muscles and increases blood flow to particular areas of the body.
PHARMACOKINETICS
Absorption : It is readily absorbed from the bloodstream and the bioavailability
is only 16%.
Distribution : It is distributed in protein bound form (94% bound to plasma protein).
Metabolism : It is metabolized in the liver by an enzyme known as CYP3A4.
Excretion : It is excreted in the feces (61%) and in the urine (36%).
ADVERSE EFFECTS
1.Facial flushing
2. Headaches
3. Stomach upset
4. Diarrhea
5. Flu-like symptoms
6. Nausea
7. Back pain
8. Muscle aches
9. Low blood pressure
10. Blurred vision
11. Abnormal ejaculation
12. Prolonged erections
13. Sweating
14. General ill feeling
15. Irregular heartbeat
16. Swelling in hands, ankles, or feet
17. Shortness of breath
18. Lightheadedness
19. Fainting
In pre-existing heart disease:
1. Chest pain
2. Heart attacks
3. Death
4. Strokes
5. Palpitations and increased heart rate
6. Vision changes
CONTRAINDICATIONS
Patients on nitrate therapy
SPECIAL PRECAUTION
1. Do not take this drug more than once a day
2. Contact doctor if erection is painful or lasts longer than 4 hours
3. Heart disease
4. Recent history a heart attack (within the past 90 days)
5. Recent history of stroke or congestive heart failure (within the past 6 months)
6. Angina
7. Hypotension
8. Hypertension
9. Liver disease
10. Kidney disease
11. Sickle cell anemia
12. Multiple myeloma
13. Leukemia
14. Haemophilia
15. Stomach ulcer
16. Retinitis pigmentosa
17. Peyronie`s disease (physical deformity of the penis)
18. Diabetes
19. High cholesterol
20. Pre-existing eye problems
21. One who smoke or are over 50 years ol
d
PREGNENCY
Contraindicated
BREAST FEEDING
Contraindicated
ELDERLY
Use with caution
CHILDREN
Contraindicated
NEONATES: Contraindicated
INTERACTIONS
Nitrates: this drug increases the effect of these drugs.
INDICATIONS
Treatment of impotence.
DOSAGES
Initial dose: 10 mg / day taken 30minutes - 12 hours before sexual activity. 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.