Kamagra (Sildenafil), also referred to as Viagra Kamagra, is a generic brand of Sildenafil citrate (Viagra) used to treat male erectile dysfunction (ED). Manufactured by Ajanta Pharma (India) in a GMP certified facility, Kamagra is approved by the Indian FDA. 
This Viagra alternative acts by inhibiting cyclic GMP-specific phosphodiesterase type 5, an enzyme that is responsible for regulating the blood flow through the penis tissue by delaying the degradation of cGMP. 
Medical uses for Kamagra
Erectile dysfunction, the main condition treated with Kamagra, is defined as a persistent inability of achieving or maintaining a healthy erection for satisfactory sexual intercourse. Although not threatening, this condition influences drastically the sexual intimacy and self confidence, reducing the quality of life.
Statistics indicate up to 7% of men aged 18-29 are affected by this health problem, the prevalence of ED rising from men aged 50 to 59. 
Pulmonary arterial hypertension
According to medical research, Kamagra can be used in treating pulmonary arterial hypertension (PAH) as it normalizes the blood pressure, improving gas exchange and increasing the exercise capacity as well.
PAH, quite a rare but deadly condition, manifests through an increased blood flow, affecting around 100,000 people along the US. Among the ailments associated with PAH are cirrhosis, congenital heart diseases, thyroid diseases, portal hypertension and sickle cell disease. 
The proper dosage of Kamagra for erectile dysfunctions is 50 mg per day, taken as needed by preferably one hour prior to sexual contact. Based on personal tolerance and effectiveness, this dose may be decreased to 25 mg per day or increased to a maximum of 100 mg per day. The Kamagra pill is rapidly absorbed and its maximum effect appears 30 to 120 minutes after intake.
No more than one dosage should be used daily, preferably with a glass of water. Kamagra overdose may lead to poisoning so a control center should be contacted immediately, in case the recommended dosage is exceeded. 
The pills should be stored at room temperature, 59-86 degrees F (15-30 degrees C).
Mechanism of action
This generic brand of Sildenafil citrate is a phosphodiesterase inhibitor, which prevents cyclic GMP (guanosine monophosphate) from being degraded by the enzyme PDE5, once reaching the corpus cavernosum of the penis. This enzyme is responsible for proper erections as it triggers and restricts the contraction and relaxation of the penis muscles. Kamagra has a similar structure to that of cGMP, this being the reason it acts like a binding agent of PDE5, inhibiting it.
As a result of its action, cGMP levels increase and the muscles relax, allowing more blood flow into the penis. This leads to vasodilation of the intimal cushion of the helicine arteries, which results in better erections when a man is sexually stimulated. Without sexual stimulation cGMP is not activated so no erection appears. 
This medicine is metabolized by enzymes found inside the liver and excreted by both kidneys and liver. For maximum effects Kamagra shouldn’t be taken with high-fat meals, as fats reduce its absorption and consequently its plasma concentration. 
Detection in biological fluids
Sildenafil and its major metabolite are measured in biofluids through liquid chromatography with ultraviolet, electrochemical or mass spectrometric detection, gas chromatography-mass spectrometry .
According to scientific studies, the most common adverse reactions caused by Kamagra are allergic reactions such as swelling of the face, lips and tongue, hives, difficulties in breathing and closing of the throat. Then, chest pain and irregular heartbeats, shortness of breath, dizziness and nausea are also listed among the possible side effects of this drug.
Some Kamagra users complained of swollen legs and ankles, angina episodes as well as prolonged and painful erections, lasting longer than 4 hours (priapism) . Any of these unwanted reactions can become a serious threat for one’s health when ignored, so the intake of the pills should be stopped and emergency medical attention should be sought as soon as any of the previously mentioned effects occurs. The risks for Kamagra are very similar to those for Viagra.
Less severe adverse reactions triggered by Kamagra include flushing, nasal congestion and headaches, mild dizziness and temporary blue tint in vision. Blurred vision, increased light sensitivity, indigestion, itching and rashes as well as diarrhea  were also reported by some Kamagra users.
Certain medicines are known to increase the blood levels of this drug, thus the usage of these products should be limited: 
Alcohol can also interact with this drug, temporarily impairing the ability of getting an erection thus for getting the maximum benefit from the medication, alcoholic beverages should not be drunk before taking Kamagra.
Contraindications include: 
- Women and children
- People who have suffered myocardial infarctions or stroke within the last 6 months
- Those who experienced life-threatening arrhythmia episodes within the last months and those diagnosed with cardiac failure
- People with coronary artery disease
- Patients suffering from hypertension or resting hypotension
- Those with retinitis pigmentosa – rare inherited eye condition
Special care should also be exercised by patients with kidney or liver disease and by those allergic to sildenafil.