SILDENAFIL CITRATE

Sildenafil for oral suspension, phosphodiesterase-5 (PDE-5) inhibitor, is the citrate salt of sildenafil, a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type-5 (PDE-5). Sildenafil is also marketed as VIAGRA ® for erectile dysfunction. Sildenafil citrate, USP is designated chemically as 1-[[3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo [4,3-d] pyrimidin-5-yl)-4-ethoxyphenyl]sulfonyl]-4-methylpiperazine citrate and has the following structural formula: Sildenafil citrate, USP is a white or almost white crystalline powder with a solubility of 10mg/100ml in water and a molecular weight of 666.7. Sildenafil for oral suspension is supplied as white to off-white granular powders containing 1.57 g of sildenafil citrate (equivalent to 1.12 g sildenafil) in an amber glass bottle and in HDPE 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. The inactive ingredients include sorbitol, citric acid anhydrous, sucralose, tri-sodium citrate dihydrate, xanthan gum, titanium dioxide, sodium benzoate, colloidal silicon dioxide, carbomer homopolymer and grape flavor. In addition to the bottle, a press-in bottle adapter and an oral dosing syringe (with 0.5 mL and 2 mL dose markings) are provided. Image

Adults Sildenafil for oral suspension is indicated for the treatment of pulmonary arterial hypertension (PAH) (World Health Organization [WHO] Group I) in adults to improve exercise ability and delay clinical worsening [see Clinical Studies (14) ] . Pediatric Patients (1 to 17 Years Old) Sildenafil for oral suspension is indicated in pediatric patients 1 to 17 years old for the treatment of pulmonary arterial hypertension (PAH) (WHO Group I) to improve exercise ability and, in pediatric patients too young to perform standardized exercise testing, pulmonary hemodynamics thought to underlie improvements in exercise [see Clinical Studies (14) ] . Adults Sildenafil for oral suspension is a phosphodiesterase-5 (PDE-5) inhibitor indicated for the treatment of pulmonary arterial hypertension (PAH) (World Health Organization [WHO] Group I) in adults to improve exercise ability and delay clinical worsening. ( 1 ) Pediatric Patients (1 to 17 years old) Sildenafil for oral suspension is indicated in pediatric patients 1 to 17 years old for the treatment of pulmonary arterial hypertension (PAH) (WHO Group I) to improve exercise ability and, in pediatric patients too young to perform standard exercise testing, pulmonary hemodynamics thought to underlie improvements in exercise ( 1 , 14 )

Adults: 20 mg orally three times a day. Dose may be increased based on symptoms and tolerability. ( 2.1 ) Pediatric patients ( 2.2 ) ≤ 20 kg: 10 mg three times a day 20 kg to 45 kg: 20 mg three times a day 45 kg: 20 mg three times a day. Dose may be increased based on symptoms and tolerability. 2.1 Recommended Dosage in Adults Oral Dosage The recommended dosage of sildenafil for oral suspension is 20 mg three times a day. Dose may be titrated to a maximum of 80 mg three times a day, if required, based on symptoms and tolerability [see Clinical Studies (14) ] . Although dose-response improvement in exercise ability was not observed in short-term studies in adults with PAH, the delay in clinical worsening with long-term use of sildenafil in Study A1481324 supports dosing up to a maximum of 80 mg three times a day [see Clinical Studies (14) ] . 2.2 Recommended Dosage in Pediatric Patients Oral Dosage The recommended dosage in patients ≤ 20 kg is 10 mg three times a day. For pediatric patients 20 kg to 45 kg, the recommended dosage is 20 mg three times a day. For pediatric patients 45 kg and greater, the recommended dosage is 20 mg three times a day. A maximum dose in pediatric patients has not been identified. Based on the experience in adults, dose may be titrated to a maximum of 40 mg three times a day for pediatric patients > 45 kg, if required, based on symptoms and tolerability [see Clinical Studies (14) ] . 2.3 Reconstitution of the Powder for Oral Suspension Note: Reconstitute the contents of the bottle with a total volume of 90 mL (60 mL followed by 30 mL). Refer to the detailed instructions below. 1. Tap the bottle to loosen the powder. 2. Add 60 mL of water to the bottle. 3. Replace the cap and shake the bottle vigorously for a minimum of 30 seconds. 4. Add another 30 mL of water to the bottle. 5. Replace the cap and shake the bottle vigorously for a minimum of 30 seconds. 6. Remove cap and press the bottle adaptor into the neck of the bottle. Replace the cap on the bottle. 7. Write the expiration date of the reconstituted oral suspension on the bottle label (the expiration date of the reconstituted oral suspension is 60 days from the date of reconstitution). Incompatibilities Do not mix with any other medication or additional flavoring agent.

Sildenafil for oral suspension is contraindicated in patients with: Concomitant use of organic nitrates in any form, either regularly or intermittently, because of the greater risk of hypotension [see Warnings and Precautions (5.1) ]. Concomitant use of riociguat, a guanylate cyclase stimulator. Phosphodiesterase-5 (PDE-5) inhibitors, including sildenafil, may potentiate the hypotensive effects of riociguat. Known hypersensitivity to sildenafil or any component of the tablet, injection, or oral suspension. Hypersensitivity, including anaphylactic reaction, anaphylactic shock and anaphylactoid reaction, has been reported in association with the use of sildenafil. Use with organic nitrates or riociguat. ( 4 ) History of hypersensitivity reaction to sildenafil or any component of the tablet, injection, or oral suspension. ( 4 )

The following serious adverse events are discussed elsewhere in the labeling: Hypotension [see Warnings and Precautions (5.1) ] Vision Loss [see Warnings and Precautions (5.4) ] Hearing Loss [see Warnings and Precautions (5.5) ] Priapism [see Warnings and Precautions (5.7) ] Vaso-occlusive Crisis in Patients with Pulmonary Hypertension Secondary to Sickle Cell Disease [see Warnings and Precautions (5.8) ] Adults: Headache, dyspepsia, flushing, pain in limb, myalgia, back pain and diarrhea. ( 6.1 , 6.2 ) Children: Priapism. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Zydus Pharmaceuticals (USA) Inc. at 1-877-993-8779 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In a 12-week, placebo-controlled clinical study and an open-label extension study (SUPER-1) in 277 sildenafil-treated adults with PAH (WHO Group I) [see Clinical Studies (14) ] the adverse reactions that were reported by at least 10% of sildenafil-treated patients in any dosing group, and were more frequent in sildenafil-treated patients than in placebo-treated patients are shown in Table 1. Adverse reactions were generally transient and mild to moderate in nature. The overall frequency of discontinuation in sildenafil-treated patients was 3% (20 mg and 40 mg three times a day) and 8% (80 mg three times a day). The overall frequency of discontinuation for placebo was 3%. Table 1. Most Common Adverse Reactions in Patients Treated with Sildenafil 20 mg, 40 mg, 80 mg and Placebo Three Times Per Day in SUPER-1 (More Frequent in Sildenafil -Treated Patients than Placebo-Treated Patients) Sildenafil 20 mg (n = 69) Sildenafil 40 mg (n = 67) Sildenafil 80 mg (n = 71) Placebo (n = 70) Headache 46% 42% 49% 39% Flushing 10% 9% 16% 4% Pain in Limb 7% 15% 9% 6% Myalgia 7% 6% 14% 4% Back Pain 13% 13% 9% 11% Dyspepsia 13% 8% 13% 7% Diarrhea 9% 12% 10% 6% In a placebo-controlled fixed dose titration study (PACES-1) of sildenafil (starting with recommended dose of 20 mg and increased to 40 mg and then 80 mg all three times a day) as an adjunct to intravenous epoprostenol in patients with PAH, no new safety issues were identified except for edema, which occurred in 25% of subjects in the combined sildenafil + epoprostenol group compared with 13% of subjects in the epoprostenol group [see Clinical Studies (14) ]. In a study to assess the effects of multiple doses of sildenafil on mortality in adults with PAH (StudyA1481324), the lower dose 5 mg TID group showed a higher observed number of deaths (all related to underlying disease/disease under study), serious adverse events, and severe adverse events than the 20 mg and 80 mg TID groups [see Clinical Studies (14) ] . 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. Pediatric Patients 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) ]. 6.2 Postmarketing Experience 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. Cardiovascular Events 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. 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. Nervous System Seizure, seizure recurrence Ophthalmologic NAION [see Warnings and Precautions (5.4) and Patient Counseling Information (17) ] .

Nitrates Concomitant use of sildenafil with nitrates in any form is contraindicated [see Contraindications (4) ]. Strong CYP3A Inhibitors Concomitant use of sildenafil with strong CYP3A inhibitors is not recommended [see Clinical Pharmacology (12.3) ]. Moderate-to-Strong CYP3A Inducers 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) ]. Use with strong CYP3A inhibitors: Not recommended. ( 7 , 12.3 ) Concomitant PDE-5 inhibitors: Avoid use with Viagra ® or other PDE-5 inhibitors. ( 5.6 )