Substantially increased sildenafil bioavailability after sublingual administration in children with congenital heart disease: two case reports

Feasibility and Safety of Sildenafil to Repair Brain Injury Secondary to Birth Asphyxia (SANE-01): A Randomized, Double-blind, Placebo-controlled Phase Ib Clinical Trial

OBJECTIVE

To test feasibility and safety of administering sildenafil in neonates with neonatal encephalopathy (NE), developing brain injury despite therapeutic hypothermia (TH).

STUDY DESIGN

We performed a randomized, double-blind, placebo-controlled phase Ib clinical trial between 2016 and 2019 in neonates with moderate or severe NE, displaying brain injury on day-2 magnetic resonance imaging (MRI) despite TH. Neonates were randomized (2:1) to 7-day sildenafil or placebo (2 mg/kg/dose enterally every 12 hours, 14 doses). Outcomes included feasibility and safety (primary outcomes), pharmacokinetics (secondary), and day-30 neuroimaging and 18-month neurodevelopment assessments (exploratory).

RESULTS

Of the 24 enrolled neonates, 8 were randomized to sildenafil and 3 to placebo. A mild decrease in blood pressure was reported in 2 of the 8 neonates after initial dose, but not with subsequent doses. Sildenafil plasma steady-state concentration was rapidly reached, but decreased after TH discontinuation. Twelve percent of neonates (1/8) neonates died in the sildenafil group and 0% (0/3) in the placebo group. Among surviving neonates, partial recovery of injury, fewer cystic lesions, and less brain volume loss on day-30 magnetic resonance imaging were noted in 71% (5/7) of the sildenafil group and in 0% (0/3) of the placebo group. The rate of death or survival to 18 months with severe neurodevelopmental impairment was 57% (4/7) in the sildenafil group and 100% (3/3) in the placebo group.

CONCLUSIONS

Sildenafil was safe and well-absorbed in neonates with NE treated with TH. Optimal dosing needs to be established. Evaluation of a larger number of neonates through subsequent phases II and III trials is required to establish efficacy.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.govNCT02812433.

Treatment of pulmonary arterial hypertension in children

Pulmonary arterial hypertension (PAH) is a devastating illness causing already significant morbidity in childhood. Currently approved treatment options for children comprise the endothelin receptor antagonist bosentan, as well as the phosphodiesterase-5 inhibitor sildenafil. But PAH treatment has advanced significantly over the past decade, and new classes of targeted drug therapies, such as stimulators of the soluble guanylate cyclase (riociguat) or prostacyclin receptor agonists (selexipag), are currently evaluated regarding their efficacy and safety in children, in order to limit off-label use. Due to the different etiologies in children, such as PAH-CHD, there is no evidence that initial combination therapy in children is superior to a mono-therapy with respect to survival. Special attention should also be paid to the pharmacology of PAH drugs in children, which might be impacted by ontogeny or drug-drug-interactions. Therapeutic drug monitoring may be useful in pediatric patients. There is a clear need for more controlled studies of PAH medications, alone or in combination therapy in the pediatric age group. Data from clinical trials as well as from patient registries should be pooled to optimize drug development and evaluation, trial design, and evidence-based pharmacotherapy in pediatric patients with PAH. In this review, the current treatment options of pediatric PAH are summarized, and an overview of new treatment concepts, which are already evaluated in adults, is presented.

Mucosal drug delivery and 3D printing technologies: A focus on special patient populations

In the last decade, additive manufacturing (AM) technologies have revolutionized how healthcare provision is envisioned. The rapid evolution of these technologies has already created a momentum in the effort to address unmet personalized needs in large patient groups, especially those belonging to sensitive subgroup populations (e.g., paediatric, geriatric, visually impaired). At the same time, AM technologies have become a salient ally to overcome defined health challenges in drug formulation development by addressing not only the requirement of personalized therapy, but also problems related to lowering non-specific drug distribution and the risk of adverse reactions, enhancing drug absorption and bioavailability, as well as ease of administration and patient compliance. To this end, mucoadhesive drug delivery systems fabricated with the support of AM technologies provide competitive advantages over conventional dosage forms, aiming to entice innovation in drug formulation with special focus on sensitive patient populations.

Update on the use of sildenafil in neonatal pulmonary hypertension: a narrative review of the history, current administration, and future directions

Pulmonary hypertension (PH) is a life-threatening syndrome in neonates and has multiple and varied etiologies. However, few clinical studies have systematically evaluated the treatment regimens for this population. Phosphodiesterase (PDE) inhibitors, such as milrinone, tadalafil, dipyridamole, and sildenafil, are the most important regulators of vascular relaxation in the normal pulmonary vascular transition after birth, and these agents are widely used in the treatment of PH. Sildenafil, a representative PDE-5 inhibitor, has an important role as a single mode of therapy. However, the lack of evidence from pharmacokinetic and clinical trials has limited the emergence of standardized treatment regimens for sildenafil. There are also differing opinions among researchers regarding the best route of sildenafil administration. Due to the interindividual variability in the neonatal population, it is worth selecting the most suitable route of sildenafil administration according to the specific conditions of the neonatal population. These may be evaluated using the oxygenation index (OI), pulmonary artery pressure, mean blood pressure, and the serological index. This article reviews the clinical data on the use of sildenafil, focusing on the current and promising alternative routes of administration, which may affect subsequent clinical research in term and preterm neonates.

Sildenafil in Infants and Children

Pulmonary arterial hypertension (PAH) management has been transformed in recent times with the advent of cheap and effective diagnostic tools and therapy. Sildenafil, a phosphodiesterase-V inhibitor, has been at the centre of this treatment, and its success in treating PAH has led to its widespread uptake in adult and paediatric pulmonary hypertension (PH), as a first line treatment choice. This might apply to persistent pulmonary hypertension of the newborn (PPHN) or bronchopulmonary dysplasia, as well as to more complex diseases, such as idiopathic pulmonary hypertension. Although recent data regarding long-term mortality and the repeal of Food and Drug Administration (FDA) approval has complicated the issue, Sildenafil continues to be the major treatment option for paediatric PH for patients in a variety of contexts, and this does not seem likely to change in the foreseeable future. In this review, we provide a summary of pulmonary hypertension in infants and children and the use of Sildenafil for such diseases.

Pharmacokinetics in neonatal prescribing: evidence base, paradigms and the future

Paediatric patients, particularly preterm neonates, present many pharmacological challenges. Due to the difficulty in conducting clinical trials in these populations dosing information is often extrapolated from adult populations. As the processes of absorption, distribution, metabolism and excretion of drugs change throughout growth and development extrapolation presents risk of over or underestimating the doses required. Information about the development these processes, particularly drug metabolism pathways, is still limited with weight based dose adjustment presenting the best method of estimating pharmacokinetic changes due to growth and development. New innovations in pharmacokinetic research, such as population pharmacokinetic modelling, present unique opportunities to conduct clinical trials in these populations improving the safety and effectiveness of the drugs used. More research is required into this area to ensure the best outcomes for our most vulnerable patients.