Overview

Mechanism of Action:
Sildenafil enhances the effects of nitric oxide (NO) by inhibiting phosphodiesterase type 5 (PDE5), which is responsible for breaking down cyclic guanosine monophosphate (cGMP) in the corpus cavernosum. It does not directly affect the isolated human corpus cavernosum but works in the presence of sexual stimulation by increasing cGMP levels, which causes smooth muscle relaxation and increased blood flow to the corpus cavernosum. Sildenafil has no effect without sexual stimulation.

Dapoxetine Mechanism:
Dapoxetine is a selective serotonin reuptake inhibitor (SSRI) that helps manage premature ejaculation by inhibiting neuronal bursts of serotonin, thereby enhancing neurotransmitter action at both pre- and postsynaptic receptors.

Pharmacokinetics:

• Sildenafil Concentrations: Plasma concentrations are measured using high-performance liquid chromatography (HPLC) and mass spectroscopy. Calibration ranges are 0.1–2.0 ng/ml, with quantification thresholds of 0.3 ng/ml and 1 ng/ml for sildenafil and its active metabolite UK-103,320, respectively. Interassay variance ranges from 3.0% to 8.6%.
• Metabolism: Total plasma concentrations of sildenafil and UK-103,320 are assessed through automated enrichment and HPLC. The assay’s accuracy and bias for sildenafil and UK-103,320 are within 2.3% to 4.8%.

Pharmacodynamics:

• Selectivity: Sildenafil is highly selective for PDE5 compared to other phosphodiesterases. It is over 4,000-fold more selective for PDE5 than PDE3, which controls cardiac contractility.
• Systemic Effects: Sildenafil causes a mild and transient decrease in systemic blood pressure. At chronic doses, significant decreases in blood pressure are noted in patients with hypertension or pulmonary arterial hypertension, but at the recommended dose, no significant changes are observed.

Precautions:

• Allergies: Inform your doctor if you have allergies or if this medication contains inactive ingredients that may cause reactions.
• Medical History: Disclose any history of heart problems, stroke, kidney or liver disease, high/low blood pressure, dehydration, penile conditions, or eye problems.

Side Effects:

• Common Effects: Dizziness, headache, flushing, stomach upset, changes in vision, including increased sensitivity to light and difficulty distinguishing colors.
• Serious Effects: Seek medical help for severe dizziness, fainting, chest pain, or other significant symptoms.

Dosage:

• Administration: Typically taken 30 minutes to 1 hour before sexual activity. It can be taken up to 4 hours before sex but should not be taken more than once daily.
• Oral Suspension: Shake before measuring. Use the provided dosage syringe or a pharmaceutical dose-measuring device.

Overdose:

• Symptoms: May include low blood pressure and fainting. Seek immediate medical attention if an overdose is suspected.

Warnings:

• Nitrate Interaction: Do not use with nitrate medications or recreational drugs containing nitrates due to the risk of severe blood pressure drop.
• Alpha Blockers: Caution with alpha blockers for enlarged prostate or high blood pressure, as this may lead to a significant drop in blood pressure.

Duration of Action:

• Onset: Typically takes 30 to 60 minutes to work, with effects lasting up to 4 hours.

Drug-Drug Interactions:

• Nitrates: Can cause severe drops in blood pressure when used with nitrates.
• Alpha Blockers: May cause low blood pressure; starting with low doses of sildenafil can mitigate risks.

Adverse Effects:

• Common Issues: Diarrhea, nausea, dizziness, headache, color perception changes, temporary color blindness, indigestion.

Pregnancy:

• Erectile Dysfunction Treatment: Does not cure erectile dysfunction or increase sexual desire. Does not prevent pregnancy or sexually transmitted diseases.

Fertility:

• Effects on Sperm: No significant effect on sperm motility, count, density, or other fertility measures.

Contraindications:

• Avoid If: High blood pressure, hypotension, leukemia, ischemic heart disease, heart failure, cardiovascular diseases, or choroid retinitis.

Storage:

• Conditions: Store at room temperature, away from light and moisture. Do not store in the bathroom.

Breastfeeding:

• Safety: Limited data suggest that sildenafil and its metabolites are poorly excreted in breast milk and are unlikely to cause adverse effects in breastfed infants.

Note: 

The brand name displayed above is specific to this product. Brand names can vary depending on the manufacturer.