Liquid Sildenafil Citrate: Uses and Indications

The mean steady state volume of distribution (Vss) for sildenafil is 105 L, indicating distribution into the tissues.

• When purchasing liquid sildenafil citrate, confirm the authenticity of the source.
• It is not recommended to buy unregulated or counterfeit versions.
• Homemade or unverified formulations can be unsafe and ineffective.
• Always follow prescribed instructions to ensure safety.
• Regular blood pressure monitoring is advised while using sildenafil.
• Beware of potential allergic reactions, such as rash or swelling.
• Using alcohol with liquid sildenafil can increase side effects.
• Keep track of dosage history for medical reviews.
• Report any adverse effects to a healthcare provider immediately.
• Use of sildenafil citrate does not guarantee sexual performance.
• Consider lifestyle factors like diet and exercise for best results.

Sildenafil and its major circulating N-desmethyl metabolite are both approximately 96% bound to plasma proteins.

Other uses for this medicine

Studies in vitro have shown that sildenafil is selective for PDE5. Its effect is more potent on PDE5 than on other known phosphodiesterases (10-fold for PDE6, greater than 80-fold for PDE1, greater than 700-fold for PDE2, PDE3, PDE4, PDE7, PDE8, PDE9, PDE10, and PDE11). The approximately 4,000-fold selectivity for PDE-5 versus PDE3 is important because PDE3 is involved in control of cardiac contractility. Sildenafil is only about 10 times as potent for PDE5 compared to PDE6, an enzyme found in the retina and involved in the phototransduction pathway of the retina. This lower selectivity is thought to be the basis for abnormalities related to color vision observed with higher doses or plasma levels [see Clinical Pharmacology (12.2)].

What should I know about sildenafil before taking it?

In addition to pulmonary vascular smooth muscle and the corpus cavernosum, PDE5 is also found in other tissues including vascular and visceral smooth muscle and in platelets. The inhibition of PDE5 in these tissues by sildenafil may be the basis for the enhanced platelet anti-aggregatory activity of nitric oxide observed in vitro, and the mild peripheral arterial-venous dilatation in vivo. Patients on all sildenafil doses achieved a statistically significant reduction in mean pulmonary arterial pressure (mPAP) compared to those on placebo in a study with no background vasodilators [see SUPER-1 in Clinical Studies (14)]. Data on other hemodynamic measures for the sildenafil 20 mg three times a day and placebo dosing regimens is displayed in Table 2. The relationship between these effects and improvements in 6-minute walk distance is unknown.

Drugs you should not use with sildenafil

Patients on sildenafil medium and high dose groups achieved dose related improvements in pulmonary vascular resistance index (PVRI) and mean pulmonary arterial pressure (mPAP) compared to those on placebo [see STARTS-1 in Clinical Studies (14)]. Improvements were observed with cardiac index in all three sildenafil dose groups over placebo. Data on other hemodynamic measures for the sildenafil low, medium and high dose groups compared to placebo is displayed in Table 3. Placebo Corrected Changes in Hemodynamic Parameters by Dose Group Abbreviations: CI = cardiac index; HR = heart rate; mPAP = mean pulmonary arterial pressure; PVRI = pulmonary vascular resistance index; RAP = right atrial pressure; SVRI = systemic vascular resistance index. Note: n = 52, 56, 55, 54, 56, and 56 placebo patients for PVRI, mPAP, CI, SVRI, RAP and sildenafil premature ejaculation HR, respectively. Protein binding is independent of total drug concentrations.

• Liquid sildenafil citrate may be part of a treatment plan for erectile dysfunction.
• It may also help men with pulmonary hypertension at different doses.
• Proper disposal of unused liquid medication is important.
• Do not share your medication with others; it is prescribed for individual use.
• Always check with your doctor before stopping or changing doses.
• Be aware of the legal regulations regarding access to sildenafil in your country.
• Responsible use helps prevent dependency or misuse.
• The liquid form allows for rapid titration of dose adjustments.
• Some formulations are specially designed for topical or sublingual use.
• Remember that sexual health involves multiple factors beyond medication.
• Consult your doctor regularly to evaluate treatment effectiveness.

Bioequivalence was established between the 20 mg tablet and the 10 mg/mL oral suspension when administered as a 20 mg single oral dose of sildenafil (as citrate). Sildenafil is cleared predominantly by the CYP3A (major route) and cytochrome P450 2C9 (CYP2C9, minor route) hepatic microsomal isoenzymes.

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The major circulating metabolite results from N-desmethylation of sildenafil, and is, itself, further metabolized.

Ingredient	Quantity per 30ml	Purity (%)	Source Organism	Additives	pH Level
Sildenafil Citrate	20 mg	99.9	Chemical Synthesis	Limonene, Glycerin	4.5
Glycerin	5 ml	—	Synthetic	Preservatives (None)
Deionized Water	24 ml	—	Purified Water	Buffering Agents
Flavoring Agents	0.5 ml	—	Plant Extracts	Artificial Flavors

This metabolite has a phosphodiesterase selectivity profile similar to sildenafil and an in vitro potency for PDE-5 approximately 50% of the parent drug. In healthy volunteers, plasma concentrations of this metabolite are approximately 40% of those seen for sildenafil, so that the metabolite accounts for about 20% of sildenafil’s pharmacologic effects. In patients with PAH, however, the ratio of the metabolite to sildenafil is higher.

• The liquid form of sildenafil citrate is often prescribed for patients with swallowing difficulties.
• It provides quicker onset of action compared to traditional tablets.
• Some formulations are designed for sublingual or buccal absorption.
• This form allows for flexible dosing, especially in clinical settings.
• It should be kept out of reach of children and pets.
• Do not mix liquid sildenafil with other medications unless advised.
• Usage instructions often recommend shaking the bottle before use.
• This medication works by relaxing blood vessels in the penis.
• It should only be used under medical supervision to avoid interactions.
• Overdose can lead to severe side effects like vision changes.
• Consult a doctor for proper dosage and whether this form is suitable.

Both sildenafil and the active metabolite have terminal half-lives of about 4 hours.

Section snippets

This finding is consistent with the inhibition of PDE6, which is involved in phototransduction in the retina. An evaluation of visual function at doses up to 200 mg revealed no effects of sildenafil on visual acuity, intraocular pressure, or pupillometry. Sildenafil is rapidly absorbed after oral administration, with a mean absolute bioavailability of 41% (25 to 63%). Maximum observed plasma concentrations are reached within 30 to 120 minutes (median 60 minutes) of oral dosing in the fasted state. When sildenafil is taken with a high-fat meal, the rate of absorption is reduced, with a mean delay in Tmax of 60 minutes and a mean reduction in Cmax of 29%. After either oral or intravenous administration, sildenafil is excreted as metabolites predominantly in the feces (approximately 80% of the administered oral dose) and to a lesser extent in the urine (approximately 13% of the administered oral dose). Sildenafil Injection: The pharmacokinetic profile of sildenafil has been characterized following intravenous administration. A 10 mg dose of sildenafil injection is predicted to provide a pharmacological effect of sildenafil and its N-desmethyl metabolite equivalent to that of a 20 mg oral dose.

What other information should I know?

Single oral doses of sildenafil 100 mg administered to healthy volunteers produced decreases in supine blood pressure (mean maximum decrease in systolic/diastolic blood pressure of 8/5 mmHg). The decrease in blood pressure was most notable approximately 1 to 2 hours after dosing and was not different from placebo at 8 hours. Similar effects on blood pressure were noted with 25 mg, 50 mg, and 100 mg doses of sildenafil, therefore the effects are not related to dose or plasma levels within this dosage range. Larger effects were recorded among patients receiving concomitant nitrates [see Contraindications (4)]. Single oral doses of sildenafil up to 100 mg in healthy volunteers produced no clinically relevant effects on electrocardiogram (ECG).

6.1 Clinical Trials Experience

After chronic dosing of 80 mg three times a day to patients with PAH, no clinically relevant effects on ECG were reported. After chronic dosing of 80 mg three times a day sildenafil to healthy volunteers, the largest mean change from baseline in supine systolic and supine diastolic blood pressures was a decrease of 9 mmHg and 8.4 mmHg, respectively. After chronic dosing of 80 mg three times a day sildenafil to patients with systemic hypertension, the mean change from baseline in systolic and diastolic blood pressures was a decrease of 9.4 and 9.1 mmHg, respectively. After chronic dosing of 80 mg three times a day sildenafil to patients with PAH, lesser reductions than above in systolic and diastolic blood pressures were observed (a decrease in both of 2 mmHg). At single oral doses of 100 mg and 200 mg, transient dose-related impairment of color discrimination (blue/green) was detected using the Farnsworth-Munsell 100-hue test, with peak effects near the time of peak plasma levels. Population Pharmacokinetics Age, gender, race, and renal and hepatic function were included as factors assessed in the population pharmacokinetic model to evaluate sildenafil pharmacokinetics in patients with PAH.

• The taste of liquid sildenafil citrate can vary based on manufacturer.
• Some formulations include sweeteners to improve palatability.
• It is important to avoid contamination by using clean measuring tools.
• Never double-dose in an attempt to enhance effects.
• The liquid form may be prescribed when pills are not tolerated.
• Be attentive to any visual or hearing changes during treatment.
• It might interact with other medications, like blood thinners.
• Patients should report persistent side effects or lack of improvement.
• Follow safety labeling instructions carefully for optimal results.
• Be aware that generic versions are available in some regions.
• Knowledge of proper storage ensures medication integrity over time.

The dataset available for the population pharmacokinetic evaluation contained a wide range of demographic data and laboratory parameters associated with hepatic and renal function. None of these factors had a significant impact on sildenafil pharmacokinetics in patients with PAH.

10. Overdosage

Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy [see Clinical Pharmacology (12.3)]. No dose adjustment for mild to moderate impairment is required. Severe impairment has not been studied [see Clinical Pharmacology (12.3)]. No dose adjustment is required (including severe impairment CLcr < 30 mL/min) [see Clinical Pharmacology (12.3)].

Some side effects can be serious. If you experience any of the following symptoms, call your doctor immediately:

In studies with healthy volunteers of single doses up to 800 mg, adverse events were similar to those seen at lower doses but rates and severities were increased. In cases of overdose, standard supportive measures should be adopted as required. Renal dialysis is not expected to accelerate clearance as sildenafil is highly bound to plasma proteins and it is not eliminated in the urine. Sildenafil is also marketed as VIAGRA® for erectile dysfunction. Sildenafil for oral suspension is supplied as white to off-white granular powder containing 1.57 g of sildenafil citrate USP (equivalent to 1.12 g sildenafil) in an amber PET bottle intended for reconstitution.

Sildenafil side effects

Following reconstitution with 90 mL water, the volume of the oral suspension is 112 mL and the oral suspension contains 10 mg/mL sildenafil. In addition to the bottle, a press-in bottle adapter and an oral dosing syringe (with 1 mL and 2 mL dose markings) are provided. Sildenafil is an inhibitor of cGMP specific PDE-5 in the smooth muscle of the pulmonary vasculature, where PDE-5 is responsible for degradation of cGMP. Sildenafil, therefore, increases cGMP within pulmonary vascular smooth muscle cells resulting in relaxation. In patients with PAH, this can lead to vasodilation of the pulmonary vascular bed and, to a lesser degree, vasodilatation in the systemic circulation. In patients with PAH, the average steady-state concentrations were 20 to 50% higher when compared to those of healthy volunteers. There was also a doubling of Cmin levels compared to healthy volunteers. Both findings suggest a lower clearance and/or a higher oral bioavailability of sildenafil in patients with PAH compared to healthy volunteers. Pediatric Patients Body weight was shown to be a good predictor of drug exposure in children. Sildenafil plasma concentration half-life values were estimated to range from 2.9 to 4.4 hours for a range of 10 to 70 kg of body weight. Tmax was estimated at approximately 1 hour. Healthy elderly volunteers (65 years or over) had a reduced clearance of sildenafil, resulting in approximately 84% and 107% higher plasma concentrations of sildenafil and its active N-desmethyl metabolite, respectively, compared to those seen in healthy younger volunteers (18 to 45 years).