Dual antiplatelet therapy with acetylsalicylic acid and a thienopyridine, such as clopidogrel, is effective for the secondary prevention of cardiovascular events in patients with acute coronary syndrome, but there is still a substantial residual risk of recurrence. Although anticoagulant therapy with a vitamin K antagonist (e.g. warfarin) in conjunction with antiplatelet therapy has been shown to reduce the risk of cardiovascular events, the rates of bleeding were increased with these combination therapies; hence, triple therapy with warfarin is currently only recommended in patients at low risk of bleeding. In addition, there are other limitations associated with vitamin K antagonist therapy, including the need for routine coagulation monitoring and dose adjustment to maintain the treatment within the therapeutic range. Rivaroxaban is an oral, direct Factor Xa inhibitor; in clinical practice, it is likely that rivaroxaban will be given to patients who also receive antiplatelet therapy, such as clopidogrel. This randomized, non-blinded, three-way crossover study investigated the effect of rivaroxaban on bleeding time when co­administered with clopidogrel. In addition, the influence of clopidogrel on the safety, tolerability, pharmacodynamics and pharmacokinetics of rivaroxaban was investigated. Of 27 healthy male subjects who received a single 300 mg dose of clopidogrel, 14 were identified as clopidogrel responders and were then randomized to the following three treatments: (A) two doses of clopidogrel on two consecutive days (300 mg on day 1; 75 mg on day 2); (B) one dose of rivaroxaban (15 mg); or (C) a combination of treatments A and B (rivaroxaban given on day 2). All treatments were well tolerated. Bleeding time with co­administration of rivaroxaban and clopidogrel was significantly prolonged in four subjects, compared with either drug alone: combination treatment increased the overall least squares-means to 3.77 times baseline (90% confidence interval [CI] 2.82–4.73), compared with 1.13 times baseline (90% CI 0.17–2.09) with rivaroxaban and 1.96 times baseline (90% CI 0.10–2.91) with clopidogrel. Co-administration of clopidogrel had no significant effect on the pharmacokinetics of rivaroxaban and, when compared with rivaroxaban alone, had no further effects on Factor Xa activity or prothrombin time. Inhibition of ADP-stimulated platelet aggregation by clopidogrel was not affected by rivaroxaban. As expected, owing to the mode of action of each study drug, the results of this study demonstrated that co­administration of the Factor Xa inhibitor rivaroxaban and the antiplatelet clopidogrel increased the bleeding time in healthy subjects without affecting other pharmacokinetic or pharmacodynamic parameters of each drug. Full article

Objective: To compare the effects of dorzolamide and timolol add-on therapy in open-angle glaucoma (OAG) patients previously treated with prostaglandin analogue (Pg), by evaluating fluctuations in the intraocular (IOP), blood (BP), ocular perfusion pressures (OPP) and retrobulbar blood flow (RBF) parameters. Methods: 35 OAG patients (35 eyes), 31 women (88.6%) age 63.3 (8.9) years were evaluated in a 3 month randomized, cross-over, single-masked study. During the experiments BP, heart rate, IOP and OPP were assessed 4 times per day (8–12–16–20 h). RBF was measured twice per day (8–20 h) using Color Doppler imaging in the ophthalmic (OA), central retinal (CRA), nasal (nSPCA) and temporal (tSPCA) posterior ciliary arteries. In each vessel, peak systolic velocity (PSV) and end-diastolic velocity (EDV) were assessed and vascular resistance (RI) calculated. Results: Both add-on therapies lowered IOP in a statistically significant manner from 15.7 ± 2.4 mmHg at latanoprost baseline to 14.9 ± 2.2 mmHg using dorzolamide (p < 0.001) and 14.2 ± 1.9 mmHg using timolol (p < 0.001). The IOP lowering effect was statistically significant at 20 h, favoring timolol as compared to dorzolamide (1.4 ± 2.4 vs. 0.2 ± 2.1 mmHg), (p < 0.05). Dorzolamide add-on therapy showed smaller IOP (2.0 ± 1.4), SPP (13.3 ± 7.9), systolic BP (13.5 ± 8.7) and diastolic BP (8.4 ± 5.4) fluctuations as compared to both latanoprost baseline or timolol add-on therapies. Higher difference between morning and evening BP was correlated to decreased evening CRA EDV in the timolol group (c = −0.41; p = 0.01). With increased MAP in the morning or evening hours, we found increased evening OA RI in timolol add-on group (c = 0.400, p = 0.02; c = 0.513, p = 0.002 accordingly). Higher MAP fluctuations were related to impaired RBF parameters during evening hours-decreased CRA EDV (c = −0.408; p = 0.01), increased CRA RI (c = 0.576; p < 0.001) and tSPCA RI (c = 0.356; p = 0.04) in the dorzolamide group and increased nSPCA RI (c = 0.351; p = 0.04) in the timolol add-on group. OPP fluctuations correlated with increased nSPCA RI (c = 0.453; p = 0.006) in the timolol group. OPP fluctuations were not related to IOP fluctuations in both add-on therapies (p < 0.05). Conclusions: Both dorzolamide and timolol add-on therapies lowered IOP in a statistically significant fashion dorzolamide add-on therapy showed lower fluctuations in IOP, SPP and BP. Higher variability of daytime OPP led to impaired RBF parameters in the evening. Full article

Recent discoveries indicate that many G-protein coupled receptors (GPCRs) and channels involved in pain modulation are able to form receptor heteromers. Receptor and channel heteromers often display distinct signaling characteristics, pharmacological properties and physiological function in comparison to monomer/homomer receptor or ion channel counterparts. It may be possible to capitalize on such unique properties to augment therapeutic efficacy while minimizing side effects. For example, drugs specifically targeting heteromers may have greater tissue specificity and analgesic efficacy. This review will focus on current progress in our understanding of roles of heteromeric GPCRs and channels in pain pathways as well as strategies for controlling pain pathways via targeting heteromeric receptors and channels. This approach may be instrumental in the discovery of novel classes of drugs and expand our repertoire of targets for pain pharmacotherapy. Full article