Initially obscure hepatotoxicity attributed to sildenafil

Combination vardenifil and tadalifil drug induced liver injury; case report and review of the literature of liver injury associated with phosphodiesterase type 5 inhibitors

Background

Phosphodiesterase type 5 inhibitors (PDE5I) are prescribed for erectile dysfunction and pulmonary hypertension. Despite its widespread use, there are only seven cases of drug-induced liver injury (DILI) associated with PDE5I, none associated with vardenafil or avanafil. We report a patient who had taken vardenafil and tadalafil individually for several years without developing symptoms of liver injury. However, after taking vardenafil and tadalafil together on 2 consecutive days, he developed severe cholestasis.

Methods

Causality was determined using Roussel Uclaf causality assessment method (RUCAM).

Results

The patient is a 72-year-old White man in excellent health who drank 2 units of alcohol, three times/week. Previously, he had used vardenafil for more than 2 years and tadalafil for 3 months as single agent for erectile dysfunction without any complications. He took vardenafil and tadalafil for 2 consecutive days and 5 days later, he developed dyspepsia, loss of appetite, jaundice, and intense itching. Liver tests showed mixed cholestatic/hepatocellular pattern of injury. Histology showed marked cholestasis with minimal inflammation. He remained cholestatic for 5 weeks before a full recovery 2 months later. The patient then resumed vardenafil monotherapy with no recurrent liver dysfunction. RUCAM causality score 7 indicates that the combination of PDE5I is probable cause of liver injury. The similarities among the eight cases of PDE5I DILI include a relatively short latency, cholestatic histological features, and complete recovery. Biochemical pattern of liver injury is variable.

Conclusions

PDE5I DILI is a rare event that can result in severe acute liver injury.

Rare fatal effect of combined use of sildenafil and alcohol leading to Cerebrovascular Accident

Sildenafil is the first internationally approved drug for erectile dysfunction. Unsupervised and non-prescribed use of sildenafil among young Indian population has increased in last few years. Sildenafil helps in erection of penis by inhibiting the action of Phosphodiesterase-5 (PDE-5) enzyme, present in the vasculature of corpus cavernosum muscle and lengthens the duration of erection. Documented adverse effects of sildenafil are headache, flushing, nasal congestion, dyspepsia, and slight decrease in systolic and diastolic blood pressure. We present a rare case of sudden death due to cerebrovascular hemorrhage after sildenafil use and concomitant alcohol intake. The history is that a 41-year-old male with no significant past medical and surgical history was staying at a hotel room with a female friend; he had consumed 2 tablets of sildenafil (50 mg each) and alcohol at night. Next morning, he developed uneasiness following which he was taken to the Hospital where he was declared dead on arrival. The important autopsy findings include edematous brain with about 300 g of clotted blood in the right basal ganglia extending to bilateral ventricles, and in pons region. Other significant findings on microscopic examination were hypertrophic ventricular wall of heart, fatty changes in liver and acute tubular necrosis and hypertensive changes in the kidney. The findings are discussed in the light of the literature about the lethal complications of combined use of sildenafil and alcohol including cerebrovascular accidents. As a forensic pathologist it is the duty of the doctor to execute meticulous autopsy along with ancillary investigations including toxicological analysis and to correlate all these findings to determine the possible effects of drugs when present, so as to gather knowledge about potentially fatal drugs and further create public awareness regarding the same.

Sildenafil-Induced Acute Fulminant Hepatic Failure: Tragedy After Triumph

Sildenafil citrate is a specific phosphodiesterase type 5-enzyme blocker that can enhance the indirect impacts of nitric oxide on vascular smooth muscle and permeability via the guanosine monophosphate (c-GMP) route in the penis erectile tissue. Though the medication is well taken, particular side effects such as flushes, headache, indigestion, and retinal abnormalities have indeed been reported. Liver toxicity caused by sildenafil use is thought to be quite infrequent. There have been few studies that looked at a potential link between sildenafil usage and liver problems, and the underlying cause involved for liver toxicity is still unknown. We report a unique instance of acute severe hepatitis with fulminant hepatic failure in a 38-year-old male patient after taking sildenafil citrate. 

Identification of phosphodiesterase type-5 (PDE-5) inhibitors in herbal supplements using a tiered approach and associated consumer risk

The use of herbal supplements for improved sexual performance is a common practice amongst the youth and some senior citizens in Ghana. These products are considered 'natural' and greatly preferred over synthetic alternatives due to the assurance of little to no adverse effects by producers. However, the high rate of adulteration often compromises their safety. Forty herbal supplements, of which 25 were previously shown to result in medium to high intake of phosphodiesterase type-5 (PDE-5) inhibitors using a PDE-Glo bioassay, were further investigated using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis to examine the reliability of the bioassay and whether the observed higher responses could be ascribed to inherent plant constituents or adulterants. Results showed significant amounts of vardenafil, tadalafil and especially sildenafil, in 2, 1 and 10 samples, respectively, with total concentration levels resulting in estimated daily intakes (EDIs) above 25 mg sildenafil equivalents with six supplements even having EDIs above 100 mg sildenafil equivalents. Only one sample contained a natural ingredient (icariin), but its concentration (0.013 mg g^-1) was too low to explain the observed potency in the bioassay. The estimated concentrations of PDE-5 inhibitors in 35 supplements, according to the bioassay, were in line with those of the LC-MS/MS analysis. However, discrepancies were observed for five supplements. Further examination of one of the latter supplements using the PDE-Glo bioassay to select the positive fraction and further examination with LC-MS/MS and ¹H-NMR revealed the presence of hydroxythiohomosildenafil, a sildenafil analogue not yet included in the liquid chromatography-mass spectrometry reference library. This study demonstrates the significance of applying a tiered approach, where the use of a bioassay is followed by chemical analysis of bioactive samples in order to identify unknown bioactive compounds.

Effect of CFTR correctors on the traffic and the function of intracellularly retained ABCB4 variants

BACKGROUND & AIM

ABCB4 is expressed at the canalicular membrane of hepatocytes. This ATP-binding cassette (ABC) transporter is responsible for the secretion of phosphatidylcholine into bile canaliculi. Missense genetic variations of ABCB4 are correlated with several rare cholestatic liver diseases, the most severe being progressive familial intrahepatic cholestasis type 3 (PFIC3). In a repurposing strategy to correct intracellularly retained ABCB4 variants, we tested 16 compounds previously validated as cystic fibrosis transmembrane conductance regulator (CFTR) correctors.

METHODS

The maturation, intracellular localization and activity of intracellularly retained ABCB4 variants were analyzed in cell models after treatment with CFTR correctors. In addition, in silico molecular docking calculations were performed to test the potential interaction of CFTR correctors with ABCB4.

RESULTS

We observed that the correctors C10, C13, and C17, as well as the combinations of C3 + C18 and C4 + C18, allowed the rescue of maturation and canalicular localization of four distinct traffic-defective ABCB4 variants. However, such treatments did not permit a rescue of the phosphatidylcholine secretion activity of these defective variants and were also inhibitory of the activity of wild type ABCB4. In silico molecular docking analyses suggest that these CFTR correctors might directly interact with transmembrane domains and/or ATP-binding sites of the transporter.

CONCLUSION

Our results illustrate the uncoupling between the traffic and the activity of ABCB4 because the same molecules can rescue the traffic of defective variants while they inhibit the secretion activity of the transporter. We expect that this study will help to design new pharmacological tools with potential clinical interest.

Treatment Barriers in Portopulmonary Hypertension

Portopulmonary hypertension (PoPH) is a form of pulmonary arterial hypertension (PAH) that can develop as a complication of portal hypertension. Treatment of PoPH includes PAH-specific therapies, and in certain cases, such therapies are necessary to facilitate a successful liver transplantation. A significant number of barriers may limit the adequate treatment of patients with PoPH and explain the poorer survival of these patients when compared to patients with other types of PAH. Until recently, only one randomized controlled trial has included PoPH patients, and the majority of treatment data have been derived from relatively small observational studies. In the present article, we review some of the barriers in the treatment of patients with PoPH and implications for liver transplantation.

Drug-induced liver injury: what was new in 2008?

BACKGROUND

Given the number of publications appearing annually regarding drug-induced liver injury (DILI), there remains a need to concisely summarize each year's new crop of case series and reports as well as the advances in mechanisms of liver injury and in the field of pharmacogenomics relating to DILI.

OBJECTIVE

To present an up-to-date review of the past year's most important clinical studies and reports of DILI, placing them into context of previous publications.

METHODS

A Medline search was conducted of all manuscripts appearing in the fields "hepatotoxicity" and "drug-induced liver injury" during the calendar year 2008. The most clinically relevant English language case reports and studies exploring mechanisms and risk factors for DILI were then chosen for review, and supplemented with older literature where appropriate.

CONCLUSIONS

As in past years, 2008 was replete with publications dealing with virtually all facets of DILI, including updated incidence and prevalence data, as well as the latest information regarding mechanisms of liver injury. Data from the first 300 patients in the National Institute of Health-sponsored DILI Network registry of > 100 non-acetaminophen causes were presented. Antimicrobials and CNS drugs were responsible for > 60% of cases, with herbals and dietary supplements being increasingly reported. Identification of genetic predispositions to DILI is coming of age with the FDA calling for the testing of human leukocyte antigen B(*)5701 before the use of abacavir to reduce the risk of hypersensitivity reactions. Several groups emphasized the pitfalls in utilizing Roussel Uclaf Causality Assessment Method and other causality assessment methodologies, and an updated review appeared on the use of potentially hepatotoxic medications in patients with underlying liver disease.