Sildenafil

SILDENAFIL- sildenafil citrate tablet
AvPAK

1 INDICATIONS AND USAGE

Sildenafil tablets are indicated for the treatment of pulmonary arterial hypertension (WHO Group I) in adults to improve exercise ability and delay clinical worsening. The delay in clinical worsening was demonstrated when sildenafil tablets were added to background epoprostenol therapy [see Clinical Studies (14)].

Studies establishing effectiveness were short-term (12 to 16 weeks), and included predominately patients with New York Heart Association (NYHA) Functional Class II-III symptoms and idiopathic etiology (71%) or associated with connective tissue disease (CTD) (25%).

2 DOSAGE AND ADMINISTRATION

2.1 Sildenafil Tablets

The recommended dose of sildenafil tablets is 20 mg three times a day. Administer sildenafil tablet doses 4 to 6 hours apart.

In the clinical trial no greater efficacy was achieved with the use of higher doses. Treatment with doses higher than 20 mg three times a day is not recommended.

3 DOSAGE FORMS AND STRENGTHS

Sildenafil Tablets, USP

Sildenafil Tablets USP, 20 mg are supplied as white to off-white, round shaped, film-coated tablets with debossing ‘AN 351’ on one side and plain on the other side, containing sildenafil citrate, USP equivalent to 20 mg of sildenafil.

4 CONTRAINDICATIONS

Sildenafil tablets are 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 (5.2)] .
  • Concomitant use of riociguat, a guanylate cyclase stimulator. PDE-5 inhibitors, including sildenafil, may potentiate the hypotensive effects of riociguat.
  • Known hypersensitivity to sildenafil or any component of the tablet. Hypersensitivity, including anaphylactic reaction, anaphylactic shock and anaphylactoid reaction, has been reported in association with the use of sildenafil.

5 WARNINGS AND PRECAUTIONS

5.1 Mortality with Pediatric Use

In a long-term trial in pediatric patients with PAH, an increase in mortality with increasing sildenafil citrate dose was observed. Deaths were first observed after about 1 year and causes of death were typical of patients with PAH. Use of sildenafil citrate, particularly chronic use, is not recommended in children [see Use in Specific Populations (8.4)].

5.2 Hypotension

Sildenafil citrate has vasodilatory properties, resulting in mild and transient decreases in blood pressure. Before prescribing sildenafil citrate, carefully consider whether patients with certain underlying conditions could be adversely affected by such vasodilatory effects (e.g., patients on antihypertensive therapy or with resting hypotension [BP less than 90/50], fluid depletion, severe left ventricular outflow obstruction, or autonomic dysfunction). Monitor blood pressure when co-administering blood pressure lowering drugs with sildenafil citrate.

5.3 Worsening Pulmonary Vascular Occlusive Disease

Pulmonary vasodilators may significantly worsen the cardiovascular status of patients with pulmonary veno-occlusive disease (PVOD). Since there are no clinical data on administration of sildenafil citrate to patients with veno-occlusive disease, administration of sildenafil citrate to such patients is not recommended. Should signs of pulmonary edema occur when sildenafil citrate is administered, consider the possibility of associated PVOD.

5.4 Epistaxis

The incidence of epistaxis was 13% in patients taking sildenafil citrate with PAH secondary to CTD. This effect was not seen in idiopathic PAH (sildenafil citrate 3%, placebo 2%) patients. The incidence of epistaxis was also higher in sildenafil citrate-treated patients with a concomitant oral vitamin K antagonist (9% versus 2% in those not treated with concomitant vitamin K antagonist).

The safety of sildenafil citrate is unknown in patients with bleeding disorders or active peptic ulceration.

5.5 Visual Loss

When used to treat erectile dysfunction, non-arteritic anterior ischemic optic neuropathy (NAION), a cause of decreased vision including permanent loss of vision, has been reported postmarketing in temporal association with the use of phosphodiesterase type 5 (PDE-5) inhibitors, including sildenafil. Most, but not all, of these patients had underlying anatomic or vascular risk factors for developing NAION, including but not necessarily limited to: low cup to disc ratio (“crowded disc”), age over 50, diabetes, hypertension, coronary artery disease, hyperlipidemia and smoking. Based on published literature, the annual incidence of NAION is 2.5 to 11.8 cases per 100,000 males aged ≥ 50 per year in the general population.

An observational case-crossover study evaluated the risk of NAION when PDE-5 inhibitor use, as a class, occurred immediately before NAION onset (within 5 half-lives), compared to PDE-5 inhibitor use in a prior time period. The results suggest an approximate 2-fold increase in the risk of NAION, with a risk estimate of 2.15 (95% CI 1.06, 4.34). A similar study reported a consistent result, with a risk estimate of 2.27 (95% CI 0.99, 5.20). Other risk factors for NAION, such as the presence of “crowded” optic disc, may have contributed to the occurrence of NAION in these studies.

Neither the rare postmarketing reports, nor the association of PDE-5 inhibitor use and NAION in the observational studies, substantiate a causal relationship between PDE-5 inhibitor use and NAION [see Adverse Reactions (6.2)] .

Advise patients to seek immediate medical attention in the event of a sudden loss of vision in one or both eyes while taking PDE-5 inhibitors, including sildenafil citrate. Physicians should also discuss the increased risk of NAION with patients who have already experienced NAION in one eye, including whether such individuals could be adversely affected by use of vasodilators, such as PDE-5 inhibitors.

There are no controlled clinical data on the safety or efficacy of sildenafil citrate in patients with retinitis pigmentosa, a minority whom have genetic disorders of retinal phosphodiesterases. Prescribe sildenafil citrate with caution in these patients.

5.6 Hearing Loss

Cases of sudden decrease or loss of hearing, which may be accompanied by tinnitus and dizziness, have been reported in temporal association with the use of PDE-5 inhibitors, including sildenafil citrate. In some of the cases, medical conditions and other factors were reported that may have played a role. In many cases, medical follow-up information was limited. It is not possible to determine whether these reported events are related directly to the use of sildenafil citrate, to the patient’s underlying risk factors for hearing loss, a combination of these factors, or to other factors.

Advise patients to seek prompt medical attention in the event of sudden decrease or loss of hearing while taking PDE-5 inhibitors, including sildenafil citrate.

5.7 Combination with other PDE-5 Inhibitors

Sildenafil is also marketed as VIAGRA ®. The safety and efficacy of combinations of sildenafil citrate with VIAGRA or other PDE-5 inhibitors have not been studied. Inform patients taking sildenafil citrate not to take VIAGRA or other PDE-5 inhibitors.

5.8 Priapism

Use sildenafil citrate with caution in patients with anatomical deformation of the penis (e.g., angulation, cavernosal fibrosis, or Peyronie’s disease) or in patients who have conditions, which may predispose them to priapism (e.g., sickle cell anemia, multiple myeloma, or leukemia). In the event of an erection that persists longer than 4 hours, the patient should seek immediate medical assistance. If priapism (painful erection greater than 6 hours in duration) is not treated immediately, penile tissue damage and permanent loss of potency could result.

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