In vitro genotoxic perspective of Tamiflu

Assessment of genetic damage induced by gadolinium-based radiocontrast agents

BACKGROUND

Today, although gadolinium based contrast agents have been frequently used in the field of medicine, there is limited data available whether gadolinium based agents affect the genome.

AIM

The present study aimed to investigate the genotoxic and cytotoxic potentials of gadoteric acid and gadoversetamide used as gadolinium-based contrast agents for magnetic resonance (MR) imaging.

MATERIAL AND METHODS

The cytokinesis-block micronucleus assay was applied to human peripheral blood lymphocytes to assess the genotoxicity measured as micronucleus (MN), nucleoplasmic bridge (NPBs) and nuclear bud (NBUDs) frequencies. Furthermore, cytokinesis-block proliferation index (CBPI) was calculated to determine cytostasis. Lymphocytes were treated with gadoteric acid at concentrations of 1.0, 2.5, 5.0, and 25 mM and with gadoversetamide at concentrations of 0.25, 1.0, 2.5, and 5.0 mM for 48 h.

RESULTS

Gadoteric acid did not cause significant increase in MN, NBPs and NBUDs frequencies and CBPI values at any concentration. Gadoversetamide induced significantly increase MN formation at concentration of 2.5 mM, NBP formation at concentrations of 1.0 and 2.5 mM, and NBUD formation at concentrations of 0.25, 1.0 and 2.5 mM. Additionally, gadoversetamide exposure resulted in statistically significant decrease in CBPI values compared to the control at concentrations of 2.5 and 5.0 mM. In addition, CBPI levels in response to concentrations of gadoversetamide was negatively and significantly associated with concentration.

CONCLUSION

These findings show that gadoteric acid does not have genotoxic or cytotoxic potential, while gadoversetamide might have both genotoxic and cytotoxic potential on human peripheral blood lymphocytes. As a comparison, gadoversetamide was found more genotoxic and cytotoxic.

Assessment of the genotoxic potential of a migraine-specific drug by comet and cytokinesis-block micronucleus assays

Background: Eletriptan is a migraine-specific drug-containing the triptan group. In terms of drug safety, the present study aimed to investigate the genotoxic potential of eletriptan.Research design & methods: We conducted our study by using the cytokinesis-block micronucleus cytome (CBMN) assay, a comprehensive method for measuring micronucleus formation, and a sensitive method for detecting DNA-strand breaks. In the assay, cytokinesis-block proliferation index and the frequency of micronuclei were evaluated in lymphocytes treated with three different concentrations (1, 10 and 25 µg/ml) of eletriptan for 48 hours. In comet assays, DNA damage was evaluated in leucocytes treated with three different concentrations (1, 10 and 25 µg/ml) of eletriptan for an hour.Results: Eletriptan did not induce cytotoxicity nor any increased micronuclei frequencies. While the comet parameters % DNA in tail, tail moment, and the olive moment was found to be significantly increased at 10 and 25 µg/ml, the cytokinesis-block proliferation index values were not.Conclusion: These findings suggest that eletriptan is non-cytotoxic but potentially weakly genotoxic at higher concentrations (10 and 25 µg/ml).

Severe Pulmonary Infection in a 20-Month-Old Female

Community-Acquired Pneumonia (CAP) is a common reason for hospitalization of a pediatric patient. We report a 20-month-old female admitted for suspected CAP. History included a week-long cough, fever, dyspnea, single occurrence of seizure-like activity, and a sick contact. Initial chest X-ray (CXR) showed left lower lobe pneumonia and parapneumonic effusion with a complex left pleural effusion. Ultrasound findings prompted the need for contrast-enhanced computed tomography (CT) of the chest. Contrast-enhanced CT of the chest confirmed a large pleural effusion with major atelectasis and mediastinal shift. The patient was treated with empiric antibiotics, video-assisted thoracoscopic surgical (VATS) decortication of empyema, and chest tube placement. Due to intraoperative complications, the VATS decortication was aborted and patient was transferred to the pediatric intensive care unit (PICU). A thoracentesis with culture failed to isolate a bacterial organism. Dexamethasone was started after repeat CXR showed persistent infiltrate. Subsequent contrast-enhanced CT of the chest showed a large collection of air and persistent consolidation. The patient received repeat VATS decortication and reinsertion of a chest tube. Repeat pleural fluid cultures failed to isolate a bacterial organism. Infectious disease (ID) consult recommended linezolid 140 mg Q8H for 4 weeks. Seven days after second VATS, a respiratory pathogen panel was positive for rhinovirus/enterovirus. With resolution of leukocytosis and clinical improvement, the patient was discharged with the chest tube in place and pediatric surgery outpatient follow-up. After three months, sequalae from both the infection and interventions presented .

Utilization of human nuclear receptors as an early counter screen for off-target activity: a case study with a compendium of 615 known drugs

Off-target effects of drugs on nuclear hormone receptors (NHRs) may result in adverse effects in multiple organs/physiological processes. Reliable assessments of the NHR activities for drug candidates are therefore crucial for drug development. However, the highly permissive structures of NHRs for vastly different ligands make it challenging to predict interactions by examining the chemical structures of the ligands. Here, we report a detailed investigation on the agonistic and antagonistic activities of 615 known drugs or drug candidates against a panel of 6 NHRs: androgen, progesterone, estrogen α/β, and thyroid hormone α/β receptors. Our study revealed that 4.7 and 12.4% compounds have agonistic and antagonistic activities, respectively, against this panel of NHRs. Nonetheless, potent, unintended NHR hits are relatively rare among the known drugs, indicating that such interactions are perhaps not tolerated during drug development. However, we uncovered examples of compounds that unintentionally agonize or antagonize NHRs. In addition, a number of compounds showed multi-NHR activities, suggesting that the cross-talk between multiple NHRs co-operate to elicit in vivo effects. These data highlight the merits of counter screening drug candidate against NHRs during drug discovery/development.