Last performance with VIAGRA: post-mortem identification of sildenafil and its metabolites in biological specimens including hair sample

Association between sexual activity-related death and non-prescription use of phosphodiesterase type 5 inhibitors

In recent years, there has been an increase in the use of phosphodiesterase type 5 inhibitors (PDE5i) that are purchased from abroad without a doctor's diagnosis via the Internet or other means. We report six cases in which nonprescription use of PDE5i may have led to death. Among the four deceased individuals who were believed to have experienced sudden cardiac death, three (cases 1-3) had a history of cardiovascular disease, which is a contraindication, and the remaining case (case 4) involved combined use of multiple PDE5i. Sildenafil (0.063 µg/mL, 0.087 µg/mL) was detected in two of the four cases of sudden cardiac death. Tadalafil (0.096 µg/mL) was detected in one of the remaining two cases, and tadalafil (0.197 µg/mL) and vardenafil (0.011 µg/mL) were detected in the other case. Sildenafil (0.032 µg/mL), tadalafil (0.062 µg/mL), and ethanol were detected in a traffic accident case with a history of contraindications. In a case of asphyxiation by vomit aspiration, autopsy showed 90% stenosis in the anterior descending branch of the coronary artery, and sildenafil (0.063 µg/mL) was detected. To the best of our knowledge, this is the first report of postmortem blood levels of tadalafil and vardenafil likely contributing to the cause of death. Despite all the warnings about the dangers of using PDE5 inhibitors, cases of PDE5i contributing to death are still identified during autopsies. Therefore, raising public awareness of the risks of the risks associated with the imported drug use by individuals is necessary.

An LC-MS/MS method for the determination of five erectile dysfunction drugs and their selected metabolites in hair

The abuse of sildenafil and its analogous, accelerated by their inappropriate or illegal distribution, is a serious social issue globally. However, no studies have been conducted to monitor these drugs simultaneously in hair, which can provide valuable information on chronic drug use. In the present study, an LC-MS/MS method was developed for the simultaneous determination in hair of five erectile dysfunction drugs having a high risk for abuse (mirodenafil, sildenafil, tadalafil, udenafil and vardenafil) and their selected metabolites (SK3541, desmethylsildenafil, DA8164 and desethylvardenafil). The novel method was fully validated after optimizing matrix effects and extraction efficiency. The optimized sample preparation included acidic methanol extraction followed by solid phase extraction using C18 mixed mode strong cation exchange polymeric cartridges. The prepared samples were analyzed by LC-MS/MS with electrospray ion source in the positive ionization mode. The validation results proved the method to be selective, sensitive, accurate and precise, with acceptable linearity within calibration ranges. LODs ranged from 0.05 (DA8164) to 1 ng/10 mg hair (tadalafil). LOQs were 1 ng/10 mg hair except for DA8164 and vardenafil, of which they were 2.5 ng/10 mg hair. No significant variations were observed by different sources of matrices in both human and rat hair, except for tadalafil, for which a stable isotope-labeled internal standard was effective. The animal study suggested hair pigmentation was a major factor for the incorporation of the drugs and metabolites into hair. However, a wide variation of the sildenafil-to-desmethylsildenafil ratios was observed in human hair samples. The developed method will be very useful for monitoring the abuse of erectile dysfunction drugs for both legal and public health aspects.

Development and validation of RP-HPLC method for sildenafil citrate in rat plasma-application to pharmacokinetic studies

Sildenafil citrate (SIL) is used in the treatment of erectile dysfunction and other chronic disorders. For the pharmacokinetic investigation of SIL we developed a simple and sensitive method for the estimation of SIL in rat plasma by reverse phase high-performance liquid chromatography (RP-HPLC). The drug samples were extracted by liquid-liquid extraction with 300 μl of acetonitrile and 5 ml of diethyl ether. Chromatographic separation was achieved on C18 column using methanol:water (85:15 v/v) as mobile phase at a flow rate of 1 ml/min and UV detection at 230 nm. The retention time of SIL was found to be 4.0 min having a separation time less than 5 min. The developed method was validated for accuracy, precision, linearity and recovery. Linearity studies were found to be acceptable over the range of 0.1-6 μg/ml. The method was successfully applied for the analysis of rat plasma sample for the application in pharmacokinetic study, drug interaction, bioavailability and bioequivalence.

Subarachnoid hemorrhage during sexual activity after sildenafil intake: an accidental association?

We report and describe an autopsy case of a man dead for rupture of cerebral artery aneurysm with subsequent subarachnoid hemorrhage after sexual intercourse. Toxicologic analysis demonstrated that he had consumed sildenafil (Viagra). Although subarachnoid hemorrhage has been reported to be associated with sexual intercourse, it is not among the known adverse effects of sildenafil. However, sildenafil has been found to interact with vascular physiology via multiple mechanisms and in most of the vascular districts of the human body. This case provides an example of a very rare association between this drug and a fatal pathologic event and deserves to be added to the existing clinical knowledge about sildenafil and the pathophysiology of the events involved. This knowledge may be helpful in orienting further investigation into the mechanisms of action of sildenafil and their clinical implications.

Analytical pitfalls in hair testing

This review focuses on possible pitfalls in hair testing procedures. Knowledge of such pitfalls is useful when developing and validating methods, since it can be used to avoid wrong results as well as wrong interpretations of correct results. In recent years, remarkable advances in sensitive and specific analytical techniques have enabled the analysis of drugs in alternative biological specimens such as hair. Modern analytical procedures for the determination of drugs in hair specimens - mainly by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) - are reviewed and critically discussed. Many tables containing information related to this topic are provided.

Simultaneous determination of sildenafil and N-desmethyl sildenafil in human plasma by high-performance liquid chromatography method using electrochemical detection with application to a pharmacokinetic study

A method which employed high-performance liquid chromatography coupled with electrochemical detection was developed for the simultaneous determination of sildenafil and its metabolite, N-desmethyl sildenafil, in human plasma has. The method was developed and validated for purposes of its application to a pharmacokinetic study in healthy volunteers after an oral dose of 50mg/tablet under fasting conditions. High precision and accuracy were demonstrated. A one-step liquid-liquid extraction further provides a simple and practical way to process plasma samples containing sildenafil with good quantitative recovery. Sampling lasted for 24h after dosing; consequently a limit of quantitation (LOQ) of 7.858 ng/mL was achieved for sildenafil whereas a LOQ of 8.675 ng/mL was obtained for N-desmethyl sildenafil. The mobile phase consisted of acetonitrile, methanol and phosphate buffer (0.05 M) (18.5:34.5:47.0, v/v/v) pH 7.68. The stationary phase was a C(8) (150 mm x 4.6 mm), 5 microm particle size operated at 27 degrees C. All analytes were stable at the pH of the supernatant, and during the analytical time window. At the applied potential of +1.20 V versus Ag/AgCl, no interferences from endogenous plasma compounds were recorded at the retention times of sildenafil, N-desmethyl sildenafil. High resolution was obtained between the analytes and the employed internal standards.

State of the art in hair analysis for detection of drug and alcohol abuse

Hair differs from other materials used for toxicological analysis because of its unique ability to serve as a long-term storage of foreign substances with respect to the temporal appearance in blood. Over the last 20 years, hair testing has gained increasing attention and recognition for the retrospective investigation of chronic drug abuse as well as intentional or unintentional poisoning. In this paper, we review the physiological basics of hair growth, mechanisms of substance incorporation, analytical methods, result interpretation and practical applications of hair analysis for drugs and other organic substances. Improved chromatographic-mass spectrometric techniques with increased selectivity and sensitivity and new methods of sample preparation have improved detection limits from the ng/mg range to below pg/mg. These technical advances have substantially enhanced the ability to detect numerous drugs and other poisons in hair. For example, it was possible to detect previous administration of a single very low dose in drug-facilitated crimes. In addition to its potential application in large scale workplace drug testing and driving ability examination, hair analysis is also used for detection of gestational drug exposure, cases of criminal liability of drug addicts, diagnosis of chronic intoxication and in postmortem toxicology. Hair has only limited relevance in therapy compliance control. Fatty acid ethyl esters and ethyl glucuronide in hair have proven to be suitable markers for alcohol abuse. Hair analysis for drugs is, however, not a simple routine procedure and needs substantial guidelines throughout the testing process, i.e., from sample collection to results interpretation.

Inhibitory effects of sildenafil citrate on the tonus of isolated dog internal anal sphincter

PURPOSE

Although the exact pathogenesis of anal fissure is not known, hypertonicity of the internal anal sphincter might be involved in its pathogenesis as main event. To gain information about possible usefulness of the novel, smooth-muscle-relaxing drug, sildenafil, in chronic anal fissure, we investigated the effect of sildenafil citrate on acetylcholine-induced contractility of internal anal sphincter isolated from dogs.

METHODS

Internal anal sphincter strips were taken from German shepherd dogs and suspended in a tissue bath filled with Krebs solution at 37 degrees C (pH 7.4) continuously bubbled with 95 percent oxygen and 5 percent carbon dioxide, and isometric contractions were recorded. Contractions were evoked by 10 muM acetylcholine, and the effects of different concentrations of sildenafil citrate (0.1, 0.3, and 1 mM) on the isometric tension of each internal anal sphincter strip were examined. The statistical significance was analyzed by one-way analysis of variance.

RESULTS

Pretreatment with sildenafil citrate (0.1 mM) attenuated contractile response to acetylcholine (n = 3), which were significantly weak compared with the maximum contractile response to the acetylcholine alone (610 +/- 110 mg vs. 2,825.17 +/- 416 mg; n = 12; P < 0.05). Sildenafil citrate also significantly inhibited the acetylcholine-induced contractions in a dose-dependent manner when applied after.

CONCLUSIONS

This experimental in vitro study showed that sildenafil citrate relaxes acetylcholine stimulated contractions of isolated dog internal anal sphincter. This may be of importance for raising the possibility that sildenafil cit-rate may have future potential in the treatment of chronic anal fissure. Further studies are needed for a conclusive decision on possible usefulness of sildenafil citrate in patients with chronic anal fissure.

Acute Myocardial Infarction After Sildenafil Citrate Ingestion

OBJECTIVE

To report a case of acute myocardial infarction (MI) associated with the use of oral sildenafil in a nitrate-free patient.

CASE SUMMARY

A 45-year-old man was admitted to the hospital with acute left-sided chest pain, nausea, and vomiting that started approximately 30 minutes after taking sildenafil 100 mg before a sexual contact. The patient was diagnosed with an acute anterior MI, and therapy with aspirin, metoprolol, and unfractionated heparin was initiated. Early coronary reperfusion treatment with primary percutaneous transluminal coronary angioplasty was performed after initial evaluation. Balloon angioplasty followed by coronary stenting was performed successfully in the 80%-occluded left anterior descending artery. The patient was discharged one week after the coronary intervention without complication.

DISCUSSION

Sildenafil-associated MI is rarely seen in patients without documented coronary artery disease. By inhibiting phosphodiesterase type 5, sildenafil can cause an increase in cyclic guanosine monophosphate levels, which mediates the relaxation of vascular smooth muscle in the corpus cavernosum. Although sildenafil can cause a major decline in systemic arterial pressure in the existence of organic nitrates, physicians should be aware of its adverse cardiovascular effects even in nitrate-free patients. The Naranjo probability scale indicates that sildenafil was the possible cause of the MI.

CONCLUSIONS

Sildenafil may rarely be associated with MI in patients with no known cardiac history. Physicians should be aware of this rare and serious adverse reaction to sildenafil and counsel patients not to take sildenafil before undergoing a complete physical evaluation and further testing if warranted.

Simultaneous determination of sildenafil and its active metabolite UK-103,320 in human plasma using liquid chromatography-tandem mass spectrometry

A liquid chromatography-tandem mass spectrometric method for the simultaneous determination of sildenafil and its active N-demethylated metabolite, UK-103,320 in human plasma was developed. Sildenafil, UK-103,320 and the internal standard (DA-8159) were extracted from human plasma with dichloromethane at basic pH. A reverse-phase LC separation was performed on Luna phenylhexyl column with the mixture of acetonitrile-ammonium formate (10 mM, pH 6.0) (60:40, v/v) as mobile phase. The detection of analytes was performed using an electrospray ionization tandem mass spectrometry in the multiple reaction-monitoring mode. The lower limits of quantification for sildenafil and UK-103,320 were 2.0 ng/ml. The method showed a satisfactory sensitivity, precision, accuracy, recovery and selectivity.