How to Administer Liquid Sildenafil Citrate
Patients on sildenafil medium and high dose groups achieved dose related improvements in pulmonary vascular resistance index
2. Sildenafil Oral Suspension Dosage and Administration
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 sildenafil citrate 120 mg 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)]. (PVRI) and mean pulmonary arterial pressure (mPAP) compared to those on placebo [see STARTS-1 in Clinical Studies (14)].
- Liquid sildenafil citrate can be prepared by licensed compounding pharmacies.
- It is preferred by some for its rapid absorption and quick results.
- The liquid form eliminates issues with swallowing pills.
- Mixing with fruit juice or water can mask the bitter taste.
- Make sure the liquid is evenly mixed before each dose.
- Available in varying concentrations depending on medical needs.
- It’s essential to discuss health conditions with a doctor before use.
- Use caution if combining with nitrate medications, which can be dangerous.
- Some users find it more convenient for on-the-go use.
- Information on dosing should always come from a healthcare professional.
- Be aware of the potential for interactions with other drugs.
Improvements were observed with cardiac index in all three sildenafil dose groups over placebo.
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Data on other hemodynamic measures for the sildenafil low, medium and high dose groups compared to placebo is displayed in Table 3.
| Side Effect | Frequency (%) | Severity | Onset Time | Reversibility | Recommendations |
|---|---|---|---|---|---|
| Headache | 15-20 | Mild | Within 1 hour | Reversible | Hydration, pain relievers |
| Flushing | 10-15 | Mild | Within 30 mins | Reversible | Reduce dose or skip dose |
| Nasal Congestion | 8-12 | Mild | 30-60 mins | Reversible | Nasal sprays may help |
| Dyspepsia | 5-10 | Mild | 1-2 hours | Reversible | Avoid spicy food, take after meals |
| Visual Disturbances | 2-4 | Mild | Variable | Usually reversible | Consult doctor if persistent |
Placebo Corrected Changes in Hemodynamic Parameters by Dose Group Abbreviations: CI = cardiac index; HR = heart rate; mPAP =
- Liquid sildenafil citrate is often compounded by pharmacies for personalized doses.
- It is popular among men seeking discreet or fast-acting options.
- The liquid formulation can be used in combination with other therapies.
- Some users report that it provides a more natural sexual experience.
- It may be administered directly into the mouth or mixed with fluids.
- Pricing varies depending on the source and brand of liquid sildenafil.
- Always check the expiration date before using any liquid medication.
- Avoid using expired liquid sildenafil to prevent adverse effects.
- Proper storage extends the medication’s effectiveness.
- Never ingest more than the prescribed dose to prevent toxicity.
- Monitoring for side effects is critical during treatment.
mean pulmonary arterial pressure; PVRI = pulmonary vascular resistance index; RAP = right atrial pressure; SVRI = systemic vascular resistance index.
| Condition | Risk Factors | Advice | Alternative Treatment |
|---|---|---|---|
| Use with Nitrates | Severe hypotension risk | Avoid combination | Psychotherapy, Other ED meds |
| Cardiovascular Disease | Increased cardiac stress | Consult cardiologist | Lifestyle modifications |
| Retinal Disorders | Worsening of existing visual issues | Medical evaluation needed | Other PDE5 inhibitors |
| Liver or Kidney Impairment | Altered drug metabolism | Dose adjustment or avoidance | Non-pharmacological options |
Note: n = 52, 56, 55, 54, 56, and 56 placebo patients for PVRI, mPAP, CI, SVRI, RAP and HR, respectively. 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).
| Form | Typical Dosage Range | Concentration (mg/30ml) | Suitable Patients | Precautions |
|---|---|---|---|---|
| Liquid Sildenafil Citrate | 20-50 mg | 20 mg/30ml | Adults with ED | Not for children or pregnant women |
| Oral Solution | 20 mg/30ml | 20 mg/30ml | Males 18-65 | Adjust dose for liver impairment |
| Quick-dissolving Liquid | 25 mg | 25 mg/30ml | Prescribed for quick action | Avoid mixing with alcohol |
The decrease in blood pressure was most notable approximately 1 to 2 hours after dosing and was not different from placebo at 8 hours.
More about sildenafil
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)].
12.3 Pharmacokinetics
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 sildenafil softgel capsule 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.
Mechanism of Action
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. 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.
Section snippets
general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. Disease-Associated Maternal and/or Embryo/Fetal Risk Pregnant women with untreated pulmonary arterial hypertension are at risk for heart failure, stroke, preterm delivery, and maternal and fetal death. No evidence of teratogenicity, embryotoxicity, or fetotoxicity was observed in pregnant rats or rabbits dosed with sildenafil 200 mg/kg/day during organogenesis, a level that is, on a mg/m2 basis, 32- and 65-times, respectively, the recommended human dose (RHD) of 20 mg three times a day. In a rat pre- and postnatal development study, the no-observed-adverse-effect dose was 30 mg/kg/day (equivalent to 5-times the RHD on a mg/m2 basis). Limited published data from sildenafil 100 mg cost a case report describe the presence of sildenafil and its active metabolite in human milk.
CRediT authorship contribution statement
There is insufficient information about the effects of sildenafil on the breastfed infant and no information on the effects of sildenafil on milk production. Limited clinical data during lactation preclude a clear determination of the risk of sildenafil to an infant during lactation. The safety and efficacy of sildenafil have been established in pediatric patients 1 to 17 years old, for the treatment of PAH (WHO Group I) to improve exercise ability and, in patients too young to perform standard exercising testing, pulmonary hemodynamics thought to underlie improvements in exercise. Use of sildenafil for this indication is supported by evidence from adequate and well-controlled studies in adults with additional PK and safety data in pediatric patients aged 1 year and older [see Adverse Reactions (6.1), Clinical Studies (14)]. The safety and effectiveness of sildenafil have not been established in pediatric patients younger than 1 year of age.
Patient resources
During the conduct of the pediatric studies (STARTS-1 and STARTS-2) [see Clinical Studies (14)], an imbalance in the number of deaths was noted: 5/55 (9.1%), 10/74 (13.5%), and 22/100 (22%) in the sildenafil low, medium, and high dose groups, respectively. The causes of death were related to the progression of PAH. This safety observation in pediatrics was not confirmed in a study conducted in adults designed to evaluate this risk (Study A1481324). Given the beneficial effects on clinical worsening and death observed in adults with increasing doses (Study A1481324) and the expected similarity of disease in pediatrics and adults, a causal association for the observed dose-related effect on mortality in pediatric patients is unlikely, and therefore, the available data support dosing in pediatric patients > 45 kg up to a maximum of 40 mg three times a day. Clinical studies of sildenafil did not include sufficient numbers of patients aged 65 and over to determine whether they respond differently from younger patients. Larger effects were recorded among patients receiving concomitant nitrates [see Contraindications (4)].
Chemical synthesis
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. Single oral doses of sildenafil up to 100 mg in healthy volunteers produced no clinically relevant effects on electrocardiogram (ECG).
Overdose/Missed Dose
Many of these events were reported to occur during or shortly after sexual activity, and a few were reported to occur shortly after the use of sildenafil without sexual activity. Others were reported to have occurred hours to days after use concurrent with sexual activity. It is not possible to determine whether these events are related directly to sildenafil, to sexual activity, to the patient’s underlying cardiovascular disease, or to a combination of these or other factors. NAION [see Warnings and Precautions (5.4), Patient Counseling Information (17)]. Concomitant use of sildenafil with nitrates in any form is contraindicated [see Contraindications (4)].
Ann. Intern. Med.
Concomitant use of sildenafil with strong CYP3A inhibitors is not recommended [see Clinical Pharmacology (12.3)]. Concomitant use of sildenafil with moderate-to-strong CYP3A inducers (such as bosentan) decreases the sildenafil exposure. Dose up-titration of sildenafil may be needed when initiating treatment with moderate-to-strong CYP3A inducers. Reduce the dose of sildenafil to 20 mg three times a day when discontinuing treatment with moderate-to-strong CYP3A inducers [see Clinical Pharmacology (12.3) and Clinical Studies (14)]. Limited published data from randomized controlled trials, case-controlled trials, and case series do not report a clear association with sildenafil and major birth defects, miscarriage, or adverse maternal or fetal outcomes when sildenafil is used during pregnancy.
Incidence not known
There are risks to the mother and fetus from untreated pulmonary arterial hypertension (see Clinical Considerations). Animal reproduction studies conducted with sildenafil showed no evidence of embryo-fetal toxicity or teratogenicity at doses up to 32- and 65-times the recommended human dose (RHD) of 20 mg three times a day in rats and rabbits, respectively (see Data). The estimated background risk of major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S.
