[Sildenafil in the treatment of pulmonary hypertension]

Development and stability assessment of liquid paediatric formulations containing sildenafil citrate

The purpose of this study is to develop and improve oral liquids formulations of sildenafil citrate for paediatric use. Four different formulations were developed, which are as follows: two aqueous solutions of sildenafil citrate (2.5 mg/mL), with or without preservatives, and two other solutions of sildenafil in simple syrup (1.25 mg/mL), with or without preservatives. All of the formulations were physically, chemically and microbiologically stable for three months. The results of the stability studies allowed for the optimisation of formulations without preservatives due to their simplicity and their similar stable conditions when compared to the formulations containing antimicrobials. The shelf life of both formulations was three months; however, upon opening, aqueous solutions should be used within 10 days and kept refrigerated, and syrup solutions should be used within 14 days in a hospital setting.

Oral sildenafil to control pulmonary hypertension after congenital heart surgery

This study investigates the role of oral sildenafil in decreasing pulmonary pressure after congenital heart surgery. Between September 2002 and September 2004, among a group of postoperative children with large septal defects, moderate to severe pulmonary hypertension [pulmonary artery (PA) to aortic (Ao) pressure ratio of 0.76 +/- 0.17] and systemic desaturation (Ao Sat = 0.89 +/- 0.11), oral sildenafil (0.3 mg x kg(-1), every 3 hours) was administered for a period of 24-48 hours (sildenafil group). These patients were compared to a group of 22 children with similar pathologies who did not receive sildenafil (control group). Postoperative PA pressure (28.61 +/- 7.80 vs 39.40 +/- 10.80 mm Hg) and PA/Ao pressure (0.28 +/- 0.08 vs 0.41 +/- 0.11) were significantly lower in the sildenafil group ( p = 0.001 and 0.001 respectively). Pulmonary hypertensive crisis was detected in 4 patients in the control group, but none in the sildenafil group ( p = 0.02). There was no significant rise in PA pressure following discontinuation of the drug (26.30 +/- 6.66 vs 28.49 +/- 10.93 mm Hg, p = 0.366). No significant complications were noticed regarding sildenafil use. Low doses of oral sildenafil appear to be effective and safe to control postoperative PA pressure in children. Absence of rebound pulmonary hypertension, availability, and low cost of the drug are considered as its major advantages.

Oral sildenafil in infants with persistent pulmonary hypertension of the newborn: a pilot randomized blinded study

BACKGROUND

Persistent pulmonary hypertension (PPHN) occurs in as many as 6.8 of 1000 live births. Mortality is approximately 10% to 20% with high-frequency ventilation, surfactant, inhaled nitric oxide, and extracorporeal membrane oxygenation but is much higher when these therapies are not available. Sildenafil is a phosphodiesterase inhibitor type 5 that selectively reduces pulmonary vascular resistance.

OBJECTIVE

Our goal was to evaluate the feasibility of using oral sildenafil and its effect on oxygenation in PPHN.

DESIGN

This study was a proof-of-concept, randomized, masked study in infants >35.5 weeks' gestation and <3 days old with severe PPHN and oxygenation index (OI) >25 admitted to the NICU (Hospital Niño Jesús, Barranquilla, Colombia). The sildenafil solution was prepared from a 50-mg tablet. The first dose (1 mg/kg) or placebo was given by orogastric tube <30 minutes after randomization and every 6 hours. Preductal saturation and blood pressure were monitored continuously. OI was calculated every 6 hours. The main outcome variable was the effect of oral sildenafil on oxygenation. Sildenafil or placebo was discontinued when OI was <20 or if there was no significant change in OI after 36 hours.

RESULTS

Six infants with an OI of >25 received placebo, and 7 received oral sildenafil at a median age of 25 hours. All infants were severely ill, on fraction of inspired oxygen 1.0, and with similar ventilatory parameters. Intragastric sildenafil and placebo were well tolerated. In the treatment group, OI improved in all infants within 6 to 30 hours, all showed a steady improvement in pulse oxygen saturation over time, and none had noticeable effect on blood pressure; 6 of 7 survived. In the placebo group, 1 of 6 infants survived.

CONCLUSIONS

Oral sildenafil was administered easily and tolerated as well as placebo and improved OI in infants with severe PPHN, which suggests that oral sildenafil may be effective in the treatment of PPHN and underscores the need for a large, controlled trial.