Oral sildenafil citrate lacks genotoxicity and cytotoxicity in a primate model: Callithrix jacchus

Effect of early adjunctive use of oral sildenafil and inhaled nitric oxide on the outcome of pulmonary hypertension in newborn infants. A feasibility study

INTRODUCTION

Inhaled nitric oxide (iNO) is the standard therapy for infants with persistent pulmonary hypertension of the newborn (PPHN). Recently, sildenafil has been evaluated as an alternative or adjunctive pulmonary vasodilator.

OBJECTIVE

To assess the effectiveness of adding sildenafil as an early adjunctive therapy together with iNO when treating newborns with PPHN and/or hypoxemic respiratory failure.

METHODS

This is a randomized placebo trial on newborns with gestational age > 34 weeks, postnatal age < 48 hours, and diagnosed with PPHN (oxygen index (OI) ≥ 20). Newborns were randomized to two groups: Group A- received oral sildenafil and iNO, and group B- received placebo and iNO. Initial and follow up echocardiography were performed over 14 days period.

RESULTS

A total of 24 newborns were recruited; 13 of them received sildenafil in addition to iNO and 11 received iNO and placebo. The most common causes of PPHN were meconium aspiration syndrome, pneumonia, and RDS. At the starting point, OI was marginally higher in the intervention group without statistical significance (29 vs 28). There were no differences between the two groups regarding surfactant administration, incidence of pneumothoraces, and the underlying causes of PPHN. Sildenafil or placebo treatment started within 12 hours after starting iNO (8 vs 6 hours).

CONCLUSION

Early use of oral sildenafil next to iNO in cases of PPHN was tolerated well by newborns and it did not show significant adverse effects. Further studies with a larger sample size is needed to assess its effecacy.

Sildenafil and tadalafil in simulated chlorination conditions: ecotoxicity of drugs and their derivatives

Chlorination experiments on two drugs (sildenafil and tadalafil) were performed mimicking the conditions of a typical wastewater treatment process. The main transformation products were isolated by chromatographic techniques (Thin Layer Chromatography (TLC), Column Chromatography (CC), High Performance Liquid Chromatography (HPLC)) and fully characterized employing Nuclear Magnetic Resonance (NMR) and Mass Spectrometry (MS) analyses. The environmental effects of the parent compounds and transformation products were evaluated using an overall toxicity approach that considered aquatic acute and chronic toxicity on Brachionus calyciflorus and Ceriodaphnia dubia as well as mutagenesis and genotoxicity on bacterial strains. The results revealed that both parent drugs did not show high acute and chronic toxicity for the organisms utilized in the bioassays while, chronic exposure to chlorine derivatives caused inhibition of growth population on rotifers and crustaceans. A mutagenic potential was found for all the compounds investigated.

Genotoxic effects in fish induced by pharmacological agents present in the sewage of some Italian water-treatment plants

The presence of pharmaceutical substances in the municipal effluents is currently considered the principal source of bio-active molecule emissions into aquatic environments. This study analyzes the genotoxic damage caused by gemfibrozil and atorvastatin, two regulators of the hematic level of lipids, and sildenafil citrate, a vasodilator, on the teleost Danio rerio. The genotoxicity of these three compounds was evaluated using the comet assay, diffusion assay, and RAPD-PCR. The alkaline version (pH 12.1) of the comet assay was used for the erythrocytes of the zebrafish to evaluate the presence of single strand DNA breaks. Furthermore, the diffusion assay was used to estimate the number of apoptotic cells. The fish were treated with the three pharmacological agents at the average concentrations previously found at some Italian treatment plants and were then sacrificed from 5 to 35 days after exposure. The data of the comet assay showed a statistically significant loss of DNA integrity after 5 days of exposure to atorvastatin and after one week of exposure to gemfibrozil. This damage was, however, repaired after 14 days. Sildenafil citrate produced, instead, a statistically significant loss of DNA integrity at the concentrations found only after 35 days of exposure. The genotoxicity at the molecular level was tested by RAPD-PCR. The results from this investigation are in agreement with those from two other tests, confirming the efficacy of the use of the three experimental approaches for the complete evaluation of genotoxic damage.

Cytogenetic effects of sildenafil citrate (Viagra) on SWR/J mouse bone marrow cells

The present study was conducted to investigate the cytogenetic effects of sildenafil citrate in SWR/J mouse bone marrow cells. Thirty-six males and 36 females were used and divided into four groups. Each group contained 18 animals (9 males and 9 females), weighing 30–35 g. These animals were orally administered with a single dose of 13, 26 or 40 mg/kg sildenafil citrate solution. A control group received normal saline in an identical condition. The animals were sacrificed at 12, 24 or 48 h, after the treatment. Chromosome aberrations were investigated in 50 metaphases per animal.

No significant differences in the percentages of mitotic indices or in the frequencies of chromosome aberrations were observed between treated male and female mice at any doses or at any time intervals used, therefore, data from the two sexes were pooled when analyzed statistically.

No significant (p < 0.05) differences in the percentages of mitotic indices or in the frequencies of chromosome aberrations were observed between sildenafil citrate-treated groups and the control group at any doses or at any time intervals used. However, the percentages of centromeric adhesions increased significantly (p < 0.01) in treated groups as compared with the control group at all doses and at all time intervals used.

In conclusion, the results of the present study suggest that sildenafil citrate does not have cytogenetic effects on mouse bone marrow cells, but the centromeric adhesions induced by this drug need further studies to confirm them and to investigate the possible mechanism(s) responsible for such effect.