Sildenafil Oral Liquid compounded for dogs and cats.

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.

1. Indications and Usage for Sildenafil Oral Suspension

Overall, the safety data for sildenafil 80 mg TID dose in Study A1481324 was consistent with the established safety profile of sildenafil in previous adult PAH studies. Sildenafil was studied in a total of 234 PAH pediatric patients 1 to 17 years of age in a 16-week, double-blind placebo-controlled study (STARTS-1); 220 patients continued in a long-term extension study (STARTS-2). Erection increased was observed in 9% of patients treated with sildenafil in STARTS-1. No other new adverse reactions were identified in pediatric patients [see Use in Specific Populations (8.4)]. Adverse events with sildenafil injection were similar to those seen with oral tablets.

Sildenafil vs. tadalafil

The following adverse reactions have been identified during post approval use of sildenafil (marketed for both PAH and erectile dysfunction). Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. In postmarketing experience with sildenafil at doses indicated for erectile dysfunction, serious cardiovascular, cerebrovascular, and vascular events, including myocardial infarction, sudden cardiac death, ventricular arrhythmia, cerebrovascular hemorrhage, transient ischemic attack, hypertension, pulmonary hemorrhage, and subarachnoid and intracerebral hemorrhages have been reported in temporal association with the use of the drug. Most, but not all, of these patients had preexisting cardiovascular risk factors. 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. 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.

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

Sildenafil, therefore, increases cGMP within pulmonary vascular smooth muscle cells resulting in relaxation.

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In patients sildenafil 100g with PAH, this can lead to vasodilation of the pulmonary vascular bed and, to a lesser degree, vasodilatation in the systemic circulation. Studies in vitro have shown that sildenafil is selective for PDE5.

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

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 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 approximately 4,000-fold selectivity for PDE-5 versus PDE3 is important because PDE3 is involved in control of cardiac contractility.

Brand Name	Manufacturer	Concentration	Packaging	Price Range (USD)	Availability	Notes
SildeVape Liquid	PharmaTech Ltd.	20 mg/30 ml	30 ml bottle	$15-$25	Global	Approved for oral use
VidiVigo Liquid	MedicaPharma	25 mg/30 ml	30 ml bottle	$18-$28	Europe, Asia	Flavored options available
LiquidSild	BioMed Inc.	20 mg/30 ml	30 ml bottle	$20-$30	North America	Prescription only
SildenafilSolution	HealthMed Co.	20 mg/30 ml	30 ml bottle	$10-$20	Various markets	Generic versions available

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.

What side effects can this medication cause?

Others were reported to have occurred hours to sildenafil generic 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)]. Concomitant use of sildenafil with strong CYP3A inhibitors is not recommended [see Clinical Pharmacology (12.3)].

CRediT authorship contribution statement

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. There are risks to the mother and fetus from untreated pulmonary arterial hypertension (see Clinical Considerations). 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)].

• 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.

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.

6. Adverse Reactions/Side Effects

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. 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.

How should I store sildenafil?

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, sildenafil oral jelly 100 mg 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 a case report describe the presence of sildenafil and its active metabolite in human milk. There is insufficient information about the effects of sildenafil on the breastfed infant and no information on the effects of sildenafil on milk production. 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.

Mechanism of action

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)]. 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. 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)].

References (33)

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. Following reconstitution with 90 mL water, the volume of the oral suspension is 112 mL and the oral suspension contains 10 mg/mL sildenafil. Data on other hemodynamic measures for the sildenafil 20 mg three times a day and placebo dosing regimens is displayed in Table 2.

Why is this medication prescribed?

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. 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.

Experimental models of inflammatory bowel disease

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. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. The relationship between these effects and improvements in 6-minute walk distance is unknown.