The effect of sildenafil on segmental oesophageal motility and gastro-oesophageal reflux

Oral Bioavailability and Pharmacokinetics of Sildenafil Orally Disintegrating Tablets under Various Gastric pH Levels Following Administration of Omeprazole in Rats

Sildenafil citrate, an oral drug used to treat erectile dysfunction, has low water solubility and oral bioavailability. The solubility is greatly influenced by the pH, changing from 37.25 mg/mL to 0.22 mg/mL with a change in pH from 1.2 to 8.0. This indicates that the absorption may decrease in patients who use drugs, such as proton pump inhibitors (PPIs), for gastroesophageal reflux disease. To improve the absorption of sildenafil citrate at various gastric pH levels, a sildenafil citrate orally disintegrating tablet (ODT), which has a rapid disintegration feature, was produced by a 3D printing technique. Our study investigated the pharmacokinetic parameters of the sildenafil citrate ODT in rats after oral administration and compared the absorption of the sildenafil citrate ODT and sildenafil citrate commercial tablet (RLD), with and without PPI treatment. The LC/MS/MS analysis of the plasma sildenafil concentration revealed that the area under curve from time 0 to infinity (AUC0-∞) of sildenafil in the sildenafil citrate ODT group was significantly higher than in the sildenafil citrate RLD group whether it was in combination with the PPI or not (274.8% and 144%, respectively; p < 0.05). The relative systemic bioavailability of sildenafil citrate RLD significantly decreased with the PPI, but that of sildenafil citrate ODT was not affected by the PPI. These results indicate that the relative systemic bioavailability of sildenafil citrate ODT was increased when it was prepared using the 3D printing technique and the absorption of this formulation was not affected by the PPI.

Phosphodiesterase 5 (PDE-5) inhibitors (sildenafil, tadalafil, and vardenafil) effects on esophageal motility: a systematic review

BACKGROUND

Esophageal motility disorders are a group of disorders associated with dysfunctional swallowing resulting from impaired neuromuscular coordination. Phosphodiesterase 5 (PDE-5) inhibitors induce smooth relaxation and are proposed as a treatment option for esophageal motility disorders such as achalasia.

METHODS

This study is conducted based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). We systematically searched MEDLINE/ PubMed, Scopus, EMBASE, and Web of Science databases for esophageal outcomes of individuals treated with PDE5 inhibitors. A random effect meta-analysis was conducted.

RESULTS

A total of 14 studies were included. They were conducted in different countries, with Korea and Italy having the highest number of articles. The main drug assessed was sildenafil. PDE-5 inhibitors resulted in a significant reduction in lower esophageal sphincter pressure (SMD - 1.69, 95% CI: -2.39 to -0.99) and the amplitude of contractions (SMD - 2.04, 95% CI: -2.97 to -1.11). Residual pressure was not significantly different between the placebo and sildenafil groups (SMD - 0.24, 95% CI: -1.20 to 0.72). Furthermore, a recent study reported contractile integral, stating that ingestion of sildenafil leads to a significant reduction in distal contractile integral and a significant increase in proximal contractile integral.

CONCLUSION

PDE-5 inhibitors significantly reduce LES resting pressure and esophageal peristaltic vigor, decreasing esophageal body contractility and contraction reserve. Therefore, using these drugs in patients affected by esophageal motility disorders may potentially improve their condition regarding symptom relief and prevention of further associated complications. Future reports investigating larger sample size is necessary in order to establish definite evidence regarding the efficacy of these drugs.

Effects of phosphodiesterase-5 inhibitor sildenafil on esophageal secondary peristalsis: Studies with high-resolution manometry

BACKGROUND AND AIM

Secondary peristalsis contributes to the clearance of retained refluxate from the esophagus. Sildenafil, a phosphodiesterase-5 inhibitor, inhibits primary esophageal peristalsis, but its effects on secondary peristalsis remain unknown. This study sought to investigate whether sildenafil could influence physiological characteristics of secondary peristalsis by applying high-resolution manometry (HRM).

METHODS

Seventeen healthy volunteers (15 men and 2 women, aged 30.2 ± 6.4 years) underwent two HRM studies on separate days following the administration of either a placebo or 50 mg of sildenafil in a random order. Both studies were performed using a water-perfused HRM catheter containing one air injection channel positioned in the mid-esophagus. Secondary peristalsis was stimulated by a rapid mid-esophageal injection of 10 or 20 mL of air 1 h after the administration of either the placebo or sildenafil. The frequency and distal contractile integral of secondary peristalsis were then compared.

RESULTS

Complete secondary peristalsis triggered by the 20-mL air injection was more frequent than observed with the 10-mL air injection (P < 0.001). The vigor of secondary peristalsis triggered by the injection of either volume of air was lower than that of primary peristalsis (P < 0.001). Sildenafil significantly reduced the success rate (P ≤ 0.001) and vigor (P < 0.001) of secondary peristalsis relative to the effects of the placebo at both distension volumes.

CONCLUSIONS

Secondary peristalsis can be successfully triggered by rapid air injection during HRM. Sildenafil reduces both the success rate and the vigor of secondary peristalsis, similar to that seen with primary peristalsis.

Sildenafil improves clinical signs and radiographic features in dogs with congenital idiopathic megaoesophagus: a randomised controlled trial

We evaluated the efficacy of oral sildenafil citrate in dogs with congenital idiopathic megaoesophagus (CIM). Twenty-one puppies were randomly assigned to two groups (treatment and control). The dogs were given sildenafil oral suspension 1 mg/kg every 12 hours for 14 days or placebo in a masked fashion. Clinical signs (frequency of regurgitation and weight gain) and oesophagrams (relative oesophageal diameter, ROD) were evaluated in order to assess the efficacy of drug treatment, by examiners who were unaware of the study protocol. In addition, a set of in vitro experiments on isolated samples of canine lower oesophageal sphincter (LOS) was performed, and the effects of increasing concentrations of sildenafil on basal tone and electrically-stimulated motility were assessed. Sildenafil administration significantly reduced the number of regurgitation episodes (0.88±1.40 v 2.65±1.56, P<0.0001) and significantly increased weight gain in the treated dogs compared to controls (79.76±28.30 per cent v 53.40±19.30 per cent, P=0.034). ROD values, at the end of the treatment period, were significantly decreased in the sildenafil group, compared to pre-treatment values (0.97±0.19 v 0.24±0.14, P<0.0001), in contrast to control subjects (0.98±0.17 v 1.10±0.25, P=0.480). In accordance with the in vivo findings, sildenafil dose-dependently reduced basal tone and increased electrically-induced relaxation of dog LOS samples. These results suggest that sildenafil citrate helps ameliorate clinical and radiographic signs in dogs with CIM by reducing LOS tone, and could represent a novel therapeutic tool for the treatment of this disease.

Impedance as an adjunct to manometric testing to investigate symptoms of dysphagia: What it has failed to do and what it may tell us in the future

Dysphagia is a common reason for referral for investigations of oesophageal motility. Impedance measurement has now been incorporated into commercially available diagnostic manometry systems for more than a decade. This innovation, which offered the ability to record patterns of bolus transport without the need for simultaneous radiology, has for the most part failed to live up to expectations, offering few additional diagnostic insights. This review examines the potential pitfalls related to how impedance patterns are currently analysed and introduces and discusses the new concept of pressure-flow analysis integrating pressure and impedance measurements to derive new metrics linked to the pressures occurring within and around the bolus as it is being transported.

Safety and tolerability of targeted therapies for pulmonary hypertension in children

The objective of this study is to evaluate the safety and tolerability of the pharmacological treatment of pulmonary hypertension in pediatric patients. It is a retrospective, longitudinal, observational study on pediatric patients undergoing treatment with pulmonary targeted therapies. 63 patients were included (51% male), with a median age of 3.4 years (IQR, 3.6 months-10 years) and a median weight 13 kg (IQR, 6-30 kg). Congenital heart disease was the etiology of pulmonary hypertension in the majority of cases (n = 33) and 28 patients were in NYHA functional class III-IV. The most commonly used drug was sildenafil (n = 79, 56%), followed by bosentan (n = 27, 23%), and a combination of both (n = 14, 41%). 34 patients had adverse reactions (54%) with an incidence rate of 1.02 per patient per year. The most commonly reported reactions were gastrointestinal symptoms (22%) and spontaneous erections (22%) in males. Nine severe adverse reactions (10%) occurred, requiring eight treatment withdrawal and one hospital admission. Treatment with targeted therapies for pulmonary hypertension is safe in the pediatric population. Severe ADRs were uncommon both in monotherapy and in combination therapy. Combination therapy was associated with a higher rate of ADRs. We observed similar survival rates in children receiving sildenafil doses according to the European Medicines Agency (EMA) recommendations or higher.

Examination of the effects of vardenafil on esophageal function using multichannel intraluminal impedance and manometry

Background/Aims

To evaluate the effects of the phosphodiesterase type 5 (PDE5) inhibitor vardenafil on esophageal function, including bolus transit, using multichannel intraluminal impedance and esophageal manometry (MII-EM).

Methods

Sixteen healthy volunteers (15 men) underwent an MII-EM study including 10 liquid swallows and 10 viscous swallows in a seated position after fasting. Then, each subject was asked to ingest 50 mL distilled water or 10 mg vardenafil dissolved in 50 mL water, in a double-blind manner. After 25 minutes, the MII-EM study was repeated.

Results

Eight men received vardenafil and eight subjects received water. Resting and residual lower esophageal sphincter pressures differed significantly only in the vardenafil group (from 18 ± 6.7 to 6.6 ± 5.3 mmHg, P < 0.001 and from 4.9 ± 2.6 to 2.1 ± 3.6 mmHg, P = 0.006, respectively). Mean distal esophageal amplitude decreased significantly only in the vardenafil group (from 86.7 ± 41.6 to 34.0 ± 38.0 mmHg, P < 0.05). Complete bolus transits of liquid and viscous meals decreased significantly only after vardenafil ingestion (from 80.2% ± 13.8% to 49.4% ± 27.9%, P < 0.05 and from 72.8% ± 33.6% to 21.5% ± 29.0%, P = 0.01, respectively).

Conclusions

Vardenafil decreased esophageal bolus transit in the seated position, despite decreased lower esophageal sphincter pressure.

Management of noncardiac chest pain in women

Noncardiac chest pain (NCCP) is very prevalent in the community. Although mortality remains low, morbidity and the financial implications are high. Women, especially those of middle age, should be thoroughly investigated as per current guidelines for coronary artery disease before labeling their chest pain as NCCP. Gastroesophageal reflux disease is the most common cause of NCCP; however other esophageal pathology including esophageal hypersensitivity, neuromuscular disease and eosinophilic esophagitis may also cause NCCP. Proton pump inhibitors are commonly used initially to manage NCCP, although patients who do not respond to this therapy require further investigation and differing treatment regimes. This article will focus on current knowledge regarding GI tract-related NCCP management strategies.

Lower esophageal sphincter relaxation reflex kinetics: effects of peristaltic reflexes and maturation in human premature neonates

We defined the sensory-motor characteristics of the lower esophageal sphincter relaxation (LESR) (stimulus threshold volume, response onset, and relaxation period, relaxation magnitude, nadir) during maturation in human neonates. We hypothesized that LESR kinetics differs during maturation and with peristaltic reflex type. Basal and adaptive esophageal motility testing was performed (N = 20 premature neonates) at 34.7 and 39.1 wk (time 1 and time 2). Effects of midesophageal provocation with graded stimuli (N = 1,267 stimuli, air and liquids) on LESR kinetics during esophagodeglutition response (EDR) and secondary peristalsis (SP) were analyzed by mixed models. Frequency of LESR with basal primary peristalsis were different during maturation (P = 0.03). During adaptive responses with maturation, 1) the frequencies of peristaltic reflexes and LESR were similar; 2) liquid stimuli resulted in a shorter LESR response latency and LESR nadir and greater LESR magnitude (all P < 0.05); 3) media differences were noted with LESR response latency (air vs. liquids, P < 0.02); and 4) infusion flow rate-LESR were different (P < 0.01 for air and liquids). Mechanistically, 1) frequency of LESR was greater during peristaltic reflexes at both times (vs. none, P < 0.0001); 2) LESR response latency, duration, and time to complete LESR were longer with EDR (all P < 0.05, vs. SP at time 2); and 3) graded stimulus volume LESR were different for air and liquids (P < 0.01). In conclusion, sensory-motor characteristics of LESR depend on the mechanosensitive properties of the stimulus (media, volume, flow), type of peristaltic reflex, and postnatal maturation. Maturation modulates an increased recruitment of inhibitory pathways that favor LESR.

Adverse effects of drugs on the esophagus

Given the function of the esophagus to transport orally ingested solids and liquids into the stomach there are several medications with adverse effect on esophageal structures and function. Various pharmacologic agents can induce esophageal injury, promote gastroesophageal reflux by decreasing lower esophageal sphincter tone or affect esophageal perception and motility. The risks of bisphosphonates, doxycycline, ferrous sulfate, ascorbic acid, aspirin/NSAIDs and chemotherapeutic agents to induce esophageal lesions have been documented in case reports and short series. In addition to direct mucosal injury, many commonly used medications including nitroglycerins, anticholinergics, beta-adrenergic agonists, aminophyllines, and benzodiazepines promote/facilitate gastroesophageal reflux by reducing lower esophageal sphincter pressure. Additional evidence accumulates on the adverse effects of various medications on esophageal motility and perception. The treatment of medication-induced esophageal lesions includes (1) identifying and discontinuing the causative medication, (2) promoting healing of esophageal injury by decreasing esophageal acid exposure or coating already existing esophageal lesions, (3) eventual use of protective compounds.

Reflux profile of Chinese gastroesophageal reflux disease patients with combined multichannel intraluminal impedance-pH monitoring

BACKGROUND AND AIMS

To investigate the reflux profile of Chinese gastroesophageal reflux disease (GERD) patients with the aid of combined multichannel intraluminal impedance-pH (MII-pH) monitoring technique.

METHODS

Consecutive patients presented with GERD symptoms were enrolled to erosive esophagitis (EE) group, non-erosive reflux disease (NERD) group and functional heartburn (FH) group after upper endoscopy, combined MII-pH monitoring and rabeprazole test. Another 20 healthy controls (HC) were recruited.

RESULTS

Sixty-four GERD patients (EE:20, NERD:22, FH:22, HC:20) were enrolled. There were more episodes of liquid reflux and proximal reflux in EE and NERD groups than that in FH and HC groups (P < 0.05). Patients in FH and HC groups had higher proportion of mixed reflux (P = 0.000). The percentage of acid reflux in EE and NERD was much higher, while there was a higher percentage of weakly acidic reflux in FH and HC (P = 0.000). No significant difference was found in MII-pH parameters between groups with and without response to rabeprazole test except recumbent percentage time of esophageal pH value below 4 and episodes of proximal reflux.

CONCLUSION

Erosive esophagitis and NERD patients had more liquid and proximal reflux episodes than FH patients and healthy controls. Acid and liquid reflux was predominant in the former two groups, while weakly acidic and mixed reflux was predominant in the latter two groups.

Noncardiac chest pain-treatment approaches

Treatment of noncardiac chest pain is often difficult because of the heterogeneous nature of the disorder. This condition can stem from gastroesophageal reflux, visceral hyperalgesia, esophageal motility disorders, psychiatric dysfunction, abnormal biomechanical properties of the esophageal wall, sustained esophageal contractions, abnormal cerebral processing of visceral stimulation, or disrupted autonomic activity. For a treatment to be successful, diagnosis of the underlying cause is essential. This article examines three decades of studies from around the world. It concludes that new research into additional mechanisms involved in visceral pain appears promising; but that future studies using improved selective adenosine receptor antagonists and other therapeutic interventions are needed.

Oral phosphodiesterase type 5 inhibitors: nonerectogenic beneficial uses

INTRODUCTION

Phosphodiesterase type 5 (PDE5) hydrolyses cyclic guanylate monophosphate (cGMP) specifically to 5' GMP. PDE5 inhibitors were a breakthrough medication that addressed a previously unfulfilled medical need. They promoted vascular relaxation in the corpora cavernosa and penile erection during sexual stimulation. Sildenafil, vardenafil, and tadalafil were approved then introduced as effective treatments for male erectile dysfunction. This impact has stimulated academic, clinical, and industrial research.

AIM

To highlight the nonerectogenic beneficial uses of oral PDE5 inhibitors.

METHOD

A systematic review of published studies in this affair based on a Pubmed and medical subject heading databases search of all concerned articles.

MAIN OUTCOME MEASURES

Demonstrated beneficial as well as applicable uses of oral PDE5 inhibitors.

RESULTS

As chemical molecules, these drugs were shown to exert potential nonerectogenic beneficial effects. They showed efficacy as a useful adjunct in the management of pulmonary hypertension. Additional uses were extended to different utilities: essential hypertension, benign prostatic hyperplasia, gastrointestinal disorders, endothelial dysfunction, female sexual dysfunction, genital blood flow, exercise capacity, Raynaud's phenomenon, sperm motility, etc.

CONCLUSION

Exploring PDE5 inhibitors for their possible medical applications in diverse specialties seems to be beneficial in making use of these molecules for the welfare of humanity.

Sildenafil inhibits duodenal contractility via activation of the NO-K+ channel pathway

Phosphodiesterase type-5 (PDE5) specifically cleaves cyclic guanosine monophosphate (cGMP), a key intracellular secondary messenger. The PDE5 inhibitor sildenafil is a well-known vasodilator that also has gastrointestinal myorelaxant properties. In the present study, we further investigated sildenafil-induced myorelaxation in rat isolated duodenum, assessing its interaction with nitric oxide (NO) synthase and K(+) channel opening. The spontaneous contractions of duodenal strips were reversibly inhibited by sildenafil (0.1-300 microM) in a concentration-dependent manner [mean (95% confidence interval); EC(50) = 6.8 (2.7-17.3) microM]. The sildenafil-induced myorelaxation was significantly decreased by the NO synthase inhibitor N-nitro-L-arginine methyl ester [increasing the EC(50) value to 41.9 (26.1-67.3) microM]. Sodium nitroprusside or forskolin pretreatments enhanced the sildenafil-induced myorelaxation. In isolated strips pretreated with BaCl(2) (0.2 mM), 4-aminopyridine (4-AP, 3 mM), or glybenclamide (1 microM), the sildenafil-induced EC(50) value was significantly increased to 32.8 (19.1-56.4), 27.1 (15.2-48.3) and 20.1 (16.4-24.7) microM, respectively. Minoxidil (50 microM) or diazoxide (100 microM) also significantly attenuated the sildenafil-induced potency. In conclusion, the NO synthase/cyclic nucleotide pathway activation is involved in sildenafil-induced inhibition of spontaneous duodenal contractions. Its pharmacological action seems to be influenced by K(+) channel opening, especially the voltage-sensitive ones, being inhibited by 4-AP and K(ATP) channels, sensitive to glybenclamide.