Sildenafil overdose in a female patient

Sildenafil Citrate Overdose in a 3-Month Postterm Premature Infant With Pulmonary Artery Hypertension

OBJECTIVE

We aimed to describe a case of prematurely born infant with accidental sildenafil overdose.

METHODS

This was a retrospective case report followed with chart and literature review.

MAIN FINDINGS

A prematurely born infant with moderate bronchopulmonary dysplasia, corrected congenital heart disease, and pulmonary hypertension presented with an accidental sildenafil overdose. Despite the relatively high dose in this medically frail infant and the long elimination half-life of sildenafil in infants, the symptoms of sildenafil overdose in our patient were only mild. After a short and uneventful period of observation in the hospital, the patient was discharged home.

CONCLUSIONS

Sildenafil overdose can cause serious symptoms such as hypotension. However, in our case, the sildenafil overdose was well tolerated, even by a young patient with underlying heart and lung disease. We show that choices in the management of sildenafil intoxication can be made based on the knowledge of sildenafil pharmacokinetics in young children.

A Non-Fatal Self-Poisoning Attempt with Sildenafil

The phosphodiesterase type 5 inhibitor, sildenafil, is not generally known for its use as a self-poisoning drug. However, intoxication cases with lethal outcome have been described. The case presented here is of a 56-year-old man who claimed to have undertaken an unsuccessful suicide attempt by mono-ingestion of 65 tablets of 100 mg sildenafil. He arrived at the emergency department 24 h after intake with severe vomiting and symptoms of blurred vision. Clinical examination revealed no priapism. Of note was a sinus tachycardia of 100 bpm without signs of hypotension. To quantify the sildenafil concentration in serum, an high-performance liquid chromatography photo-diode array method was developed and validated according to European Medicines Agency guidelines. The intoxicated patient had a serum concentration of 22.2 µg/mL sildenafil, at the time of presentation, which is far above the therapeutic peak concentration. The serum concentration further declined to 9.2 and 2.3 µg/mL, respectively, 5 and 14 h later, revealing a biological half-life of 4.2 h. To the best of our knowledge, this patient took the highest sildenafil dose, which resulted in the highest serum concentration, ever reported. In this subject, sildenafil showed good tolerability because few symptoms occurred and only moderate supportive therapy was needed for full recovery without sequelae.

Quantification of active pharmaceutical ingredient and impurities in sildenafil citrate obtained from the Internet

BACKGROUND

The accessibility of prescription drugs produced outside of the United States, most notably sildenafil citrate (innovator product, Viagra®), has been made much easier by the Internet. Of greatest concern to clinicians and policymakers is product quality and patient safety. The US Food and Drug Administration (FDA) has issued warnings to potential buyers that the safety of drugs purchased from the Internet cannot be guaranteed, and may present a health risk to consumers from substandard products.

OBJECTIVE

The objective of this study was to determine whether generic sildenafil citrate tablets from international markets obtained via the Internet are equivalent to the US innovator product regarding major aspects of pharmaceutical quality: potency, accuracy of labeling, and presence and level of impurities. This will help identify aspects of drug quality that may impact public health risks.

METHODS

A total of 15 sildenafil citrate tablets were obtained for pharmaceutical analysis: 14 generic samples from international Internet pharmacy websites and the US innovator product. According to US Pharmacopeial guidelines, tablet samples were tested using high-performance liquid chromatography for potency of active pharmaceutical ingredient (API) and levels of impurities (impurities A, B, C, and D). Impurity levels were compared with International Conference on Harmonisation (ICH) limits.

RESULTS

Among the 15 samples, 4 samples possessed higher impurity B levels than the ICH qualification threshold, 8 samples possessed higher impurity C levels than the ICH qualification threshold, and 4 samples possessed more than 1% impurity quantity of maximum daily dose (MDD). For API, 6 of the samples failed to fall within the 5% assay limit.

CONCLUSIONS

Quality assurance tests are often used to detect formulation defects of drug products during the manufacturing and/or storage process. Results suggest that manufacturing standards for sildenafil citrate generic drug products compared with the US innovator product are not equivalent with regards to potency and levels of impurities. These findings have implications for safety and effectiveness that should be addressed by clinicians to safeguard consumers who choose to purchase sildenafil citrate and foreign-manufactured drugs, in general, via the Internet.