Plant-Derived Compounds as a Tool for the Control of Gastrointestinal Nematodes: Modulation of Abamectin Pharmacological Action by Carvone

The combination of synthetic anthelmintics and bioactive phytochemicals may be a pharmacological tool for improving nematode control in livestock. Carvone (R-CNE) has shown in vitro activity against gastrointestinal nematodes; however, the anthelmintic effect of bioactive phytochemicals either alone or combined with synthetic drugs has been little explored in vivo. Here, the pharmacological interaction of abamectin (ABM) and R-CNE was assessed in vitro and in vivo. The efficacy of this combination was evaluated in lambs naturally infected with resistant gastrointestinal nematodes. Additionally, the ligand and molecular docking of both molecules to P-glycoprotein (P-gp) was studied in silico. The presence of R-CNE produced a significant (p < 0.05) increase of Rho123 and ABM accumulation in the intestinal explants. After 60 min of incubation, Rho123 incubated with R-CNE had a 67 ± 21% higher concentration (p < 0.01) than when it was incubated alone. In the case of ABM, a significant increase in the intestinal concentrations was observed at 15 and 30 min after incubation with R-CNE. In the in vivo assay, no undesirable effects were observed after the oral administration of R-CNE. The coadministration of the natural compound prolonged ABM absorption in lambs. ABM T_½ absorption was 1.57-fold longer (p < 0.05) in the coadministered group. Concentrations of R-CNE between 420 and 2,593 ng/mL were detected in the bloodstream between 1 and 48 h posttreatment. The in vivo efficacy of ABM against gastrointestinal nematodes increased from 94.9 to 99.8% in the presence of R-CNE, with the lower confidence interval limit being >90%. In vitro/in vivo pharmacoparasitological studies are relevant for the knowledge of the interactions and the efficacy of bioactive natural products combined with synthetic anthelmintics. While ADMET (absorption, distribution, metabolism, excretion, and toxicity) predictions and the molecular docking study showed a good interaction between ABM and P-gp, R-CNE does not appear to modulate this efflux protein. Therefore, the pharmacokinetic–pharmacodynamic effect of R-CNE on ABM should be attributed to its effect on membrane permeability. The development of pharmacology-based information is critical for the design of successful strategies for the parasite control.

Flucloxacillin-warfarin interaction: an under-appreciated phenomenon

Current drug databases do not acknowledge an interaction between warfarin and flucloxacillin although case reports have indicated that flucloxacillin may increase warfarin requirement to maintain therapeutic international normalised ratio (INR). To assess whether flucloxacillin therapy leads to a significant increase in warfarin dose, we conducted a retrospective, observational, cohort study of hospital-in-the-home patients previously stable on warfarin; who were treated with flucloxacillin or other antibiotics for at least 2 weeks between June 2015 and December 2016. The outcome measured was change in average warfarin dose at two time periods: 1 week prior to antibiotic treatment and the final week of antibiotic treatment. Four cases with flucloxacillin and four comparators treated with other antibiotics met inclusion criteria. All cases treated with flucloxacillin had a clinically and statistically significant increase in warfarin dose in the final week of antibiotic treatment compared with pre-antibiotics. The warfarin dose increased by a range of 57-130% (P < 0.05). There was no significant change in warfarin dose for patients on vancomycin, benzylpenicillin or piperacillin-tazobactam. One comparator on cephazolin had a statistically significant change in warfarin dose; however, they had a sub-therapeutic INR on admission which warranted a dose increase. Due to the high risk of sequelae with sub-therapeutic anticoagulation, close INR monitoring is essential for patients on a prolonged course of flucloxacillin.

Acute memory and psychotomimetic effects of cannabis and tobacco both 'joint' and individually: a placebo-controlled trial

BACKGROUND

Cannabis and tobacco have contrasting cognitive effects. Smoking cannabis with tobacco is prevalent in many countries and although this may well influence cognitive and mental health outcomes, the possibility has rarely been investigated in human experimental psychopharmacological research.

METHOD

The individual and interactive effects of cannabis and tobacco were evaluated in 24 non-dependent cannabis and tobacco smokers in a randomized, placebo-controlled, double-blind, 2 (cannabis, placebo) × 2 (tobacco, placebo) crossover design. Verbal memory (prose recall), working memory (WM) performance including maintenance, manipulation and attention (N-back), psychotomimetic, subjective and cardiovascular measures were recorded on each of four sessions.

RESULTS

Cannabis alone impaired verbal memory. A priori contrasts indicated that tobacco offset the effects of cannabis on delayed recall. However, this was not supported by linear mixed model analysis. Cannabis load-dependently impaired WM. By contrast, tobacco improved WM across all load levels. The acute psychotomimetic effects and ratings of 'stoned' and 'dizzy' induced by cannabis were not altered by tobacco. Cannabis and tobacco had independent effects on increasing heart rate and interacting effects on increasing diastolic blood pressure.

CONCLUSIONS

Relative to placebo, acute cannabis impaired verbal memory and WM. Tobacco enhanced performance on WM, independently of cannabis. Moreover, we found some preliminary evidence that tobacco may offset the effects of cannabis on delayed, but not immediate, verbal recall. In contrast, the psychotomimetic and subjective effects of cannabis were unaffected by tobacco co-administration. By reducing the cognitive impairment from cannabis, tobacco co-administration may perpetuate use despite adverse health consequences.

Assessment of Prescribing and Monitoring Habits for Patients Taking an Antiarrhythmic and Concomitant QTc-Prolonging Antibiotic

Patients may intermittently require antimicrobial therapy with a QTc-prolonging antibiotic, which presents a challenge for prescribers of patients already taking a QTc-prolonging antiarrhythmic. Manufacturers recommend close monitoring for evidence of QTc-prolongation with the concomitant use of QTc-prolonging medications, but the monitoring parameters are not well-defined. Previous studies recommend a surveillance electrocardiogram (EKG) be completed both before and after the initiation of QTc-prolonging medications, but it is unknown to what degree EKGs displaying the QTc-interval are used to alter physician order entry and pharmacist order verification during concomitant therapy. A retrospective chart review was conducted between October 2015–September 2016 to assess prescribing and monitoring habits for patients taking an antiarrhythmic and a concomitant QTc-prolonging antibiotic. Of the 42 patients who received at least one dose of two QTc-prolonging agents, 36 (85.7%) received a baseline EKG, and 23 (63.8%) received a follow-up EKG. Pharmacists intervened on this drug–drug interaction and recommended follow-up EKGs only three times (8.3%) and offered alternative therapy recommendations once (2.8%). The QTc-interval was not optimally monitored in some instances for patients concomitantly receiving two QTc-prolonging agents. These results stress the importance of inter-professional communication to place an emphasis on follow-up monitoring or use of alternative therapy agents to avoid the drug–drug interaction altogether.

Current treatment options for hepatitis C patients co-infected with HIV

With the availability of all-oral, direct acting antivirals (DAAs), hepatitis C virus (HCV) therapy has been revolutionized for HIV/HCV co-infected patients. Indeed HCV cure rates are now no longer different between HCV mono and HIV/HCV co-infected persons and are both greater than 95%. Therefore, current treatment guidelines no longer separate these two groups. Indications for HCV treatment and choice of DAA combination are now the same for all HCV patients. In HIV/HCV co-infection however, drug interactions between HIV and HCV agents need be checked prior to starting HCV therapy. Finally, the higher risk of hepatic decompensation in HIV/HCV co-infected patients, including those receiving successful antiretroviral therapy, continues to make these patients a high priority group for receiving access to modern DAA combination therapy.

Decreased exposure to sunitinib due to concomitant administration of ifosfamide: results of a phase I and pharmacokinetic study on the combination of sunitinib and ifosfamide in patients with advanced solid malignancies

BACKGROUND

This study aimed to define the maximally tolerated dose (MTD) of sunitinib combined with two different infusion schedules of ifosfamide.

METHODS

Patients with advanced solid tumours, good performance score, good organ function, and no standard therapy available were eligible. Continuous once daily sunitinib, in escalating doses per cohort, was combined with ifosfamide, 9 g m(-2) for 3 days or 6 g m(-2) for 5 days, administered every 3 weeks. Pharmacokinetic (PK) and pharmacodynamic (PD) assessments were performed.

RESULTS

With growth-factor support, the MTD of sunitinib combined with either ifosfamide schedule was 12.5 mg in 32 patients enrolled. Neutropenia-related adverse events were dose-limiting toxicities. Sunitinib did not affect ifosfamide PK. Ifosfamide significantly decreased exposure to sunitinib and increased exposure to its metabolite, SU12662. No consistent changes in PD parameters were observed.

CONCLUSION

With growth-factor support, the MTD of sunitinib with both ifosfamide schedules was 12.5 mg. Ifosfamide produced decreased sunitinib blood levels because of CYP3A induction. As PK interactions cannot explain the relatively low sunitinib doses that can be combined with ifosfamide, synergy in toxicity is likely. Whether this also holds true for anti-tumour activity needs to be further explored.

Lack of effect of eprosartan on the single dose pharmacokinetics of orally administered digoxin in healthy male volunteers

AIMS

To study the effect of eprosartan, a nonbiphenyl tetrazole angiotensin II receptor antagonist, on digoxin pharmacokinetics in a randomized, open-label, two period, period balanced crossover study in 12 healthy men.

METHODS

Each subject received a single 0.6 mg oral dose of digoxin (Lanoxicaps 0.2 mg/capsule, Glaxo Wellcome) alone or following 4 days of dosing with eprosartan 200 mg orally every 12 h. Each study period was separated by a 14 day washout interval. Serial blood samples were obtained for up to 96 h after each digoxin dose for determination of digoxin pharmacokinetics. The effect of eprosartan on digoxin pharmacokinetics was assessed through an equivalence-type approach using AUC(0, t') as the primary endpoint.

RESULTS

For AUC(0, t'), the ratio of digoxin+eprosartan: digoxin alone was 0.99 with a 90% confidence interval (CI) of [0.90, 1.09]. For Cmax, the ratio was 1.00 with a 90% CI of [0.86, 1.17]. tmax was similar for both regimens. Both regimens were safe and well tolerated.

CONCLUSIONS

Based on AUC and Cmax data, it can be concluded that eprosartan has no effect on the pharmacokinetics of a single oral dose of digoxin.