一、請參照下列美國 FDA 於 2012/8/30 發布的警訊，回答下列問題：Revatio (sildenafil): Drug Safety Communication - Recommendation Against Use in Children[Posted 08/30/2012]AUDIENCE: Pediatrics, Cardiology, PulmonologyISSUE: FDA notified healthcare professionals and their medical care organizations that Revatio (sildenafil)should not be prescribed to children (ages 1 through 17) for pulmonary arterial hypertension (PAH).Thisrecommendation against use is based on a recent long-term clinical pediatric trial showing that: (1) childrentaking a high dose of Revatio had a higher risk of death than children taking a low dose and (2) the low dosesof Revatio are not effective in improving exercise ability. Treatment of PAH in children with this drug is anoff-label use (not approved by FDA) and a new warning, stating the use of Revatio is not recommended inpediatric patients has been added to the Revatio labeling.BACKGROUND: Revatio is a phosphodiesterase-5 inhibitor used to treat pulmonary arterial hypertensionby relaxing the blood vessels in the lungs to reduce blood pressure and is approved to improve exerciseability and delay clinical worsening of PAH in adult patients (WHO Group I).RECOMMENDATION: Patients and caregivers are advised to not change the Revatio dose or stop takingRevatio without talking to a health care professional. Healthcare professionals were reminded that use of thisproduct, particularly chronic use, in children is an off-label indication, not approved by FDA, and is notrecommended.
⑴請說明這則警訊的內容。（15 分）