INTRODUCTIONNovel oral anticoagulants (NOACs) have at least equivalent efficacy compared to standard anticoagulants with similar bleeding risk. Optimal management strategies for bleeding complications associated with NOACs are currently unestablished.

MATERIALS AND METHODSA working group comprising haematologists and vascular medicine specialists representing the major institutions in Singapore was convened to produce this consensus recommendation. A Medline and EMBASE search was conducted for articles related to the 3 available NOACs (dabigatran, rivaroxaban, apixaban), bleeding and its management. Additional information was obtained from the product monographs and bibliographic search of articles identified.

RESULTSThe NOACs still has substantial interactions with a number of drugs for which concomitant administration should best be avoided. As they are renally excreted, albeit to different degrees, NOACs should not be prescribed to patients with creatinine clearance of <30 mLs/min. Meticulous consideration of risk versus benefits should be exercised before starting a patient on a NOAC. In patients presenting with bleeding, risk stratification of the severity of bleeding as well as identification of the source of bleeding should be performed. In life-threatening bleeds, recombinant activated factor VIIa and prothrombin complex may be considered although their effectiveness is currently unsupported by firm clinical evidence. The NOACs have varying effect on the prothrombin time and activated partial thromboplastin time which has to be interpreted with caution. Routine monitoring of drug level is not usually required.

CONCLUSIONNOACs are an important advancement in antithrombotic management and careful patient selection and monitoring will permit optimisation of their potential and limit bleeding events.

Administration, Oral ; Anticoagulants ; therapeutic use ; Benzimidazoles ; Consensus ; Dabigatran ; Hemorrhage ; prevention & control ; Humans ; Singapore ; Thiophenes

In this study, the variation of pharmacokinetics behavior of raltitrexed (RTX) in rats after repeatedly injected with Huangqi injection was investigated. Twelve SD rats were divided into two groups: the multidose group and the RTX group. Rats in multidose group were iv. injected with Huangqi injection (dose of 1.575 mL x kg(-1)) everyday at 8 am for a week, and had free accesses for food and water. The rats were fasted for food but not water since 8 h before the eighth day. At the eighth morning, firstly, rats were injected with Huangqi injection (dose of 1.575 mL x kg(-1)), and 5 min later, were injected with RTX (dose of 0.467 mg x kg(-1)); rats in RTX group were not disposed in the previous seven days, also had free accesses for food and water, and were iv. injected with raltitrexed at the same time as Multidose group at the eighth day morning. Rat plasma was collected at different time and processed with methanol to precipitate the protein before HPLC assays. The pharmacokinetics parameters for two groups were calculated by software 3P97. Through the observation of drug concentration in plasma and time curve, we found that at almost every time point the concentration of RTX in plasma in multidose group was lower than the RTX group. When comparing the pharmacokinetics parameters between the multidose group and the RTX group, the average of AUC(0-t) and half-life(t1/2) of multidose group were decreased from 56 080 microg x min x L(-1) and 15.07 min to 35 834 microg x min x L(-1) and 8.95 min, respectively, while the clearance (CL) was increased from 0.51 to 0.83 mL x h(-1). Therefore, it could be deduced that repeatedly injected with AR injection may influence the renal excretion and glycometabolism of RTX, thus change pharmacokinetics behavior of raltitrexed in rats plasma. This result may give us a hint to prudantly manage the drug combination of RTX and Huangqi injection.
Animals ; Drugs, Chinese Herbal ; administration & dosage ; pharmacokinetics ; Female ; Injections ; Male ; Quinazolines ; administration & dosage ; blood ; pharmacokinetics ; Rats ; Rats, Sprague-Dawley ; Thiophenes ; administration & dosage ; blood ; pharmacokinetics

Aggressive intravenous and oral dual antiplatelet therapy has established primary percutaneous coronary intervention (PCI) as the standard of care for acute myocardial infarction. Clopidogrel is currently the thienopyridine of choice for dual antiplatelet therapy in patients treated with PCI. The dose regime and duration of therapy of clopidogrel has undergone multiple refinements. Recently, 2 novel third generation oral inhibitors of P2Y12 receptors, prasugrel and ticagrelor, have undergone clinical evaluation with promising results. This article is a non-exhaustive review of the literature, concentrating on the role of current and novel oral antiplatelet agents for acute myocardial infarction particularly highlighting the limitations and issues associated with clopidogrel use.
Adenosine ; administration & dosage ; analogs & derivatives ; Angioplasty, Balloon, Coronary ; Drug Therapy, Combination ; Electrocardiography ; Humans ; Myocardial Infarction ; drug therapy ; surgery ; Piperazines ; administration & dosage ; Platelet Aggregation Inhibitors ; administration & dosage ; Prasugrel Hydrochloride ; Thiophenes ; administration & dosage ; Ticlopidine ; administration & dosage ; analogs & derivatives

To study pharmacokinetics behavior of Raltitrexed (RTX) after single injected with Radix Astragali (RA); twelve rats were divided into two groups: RTX (administrated iv. of raltitrexed); RTX with RA (administrated iv. of raltitrexed after single iv. dose of 3. 15 g x kg(-1)), rat plasma was collected and processed before HPLC assays; The established HPLC method was rapid, specific and precise. Between RTX and RTX with RA groups, half-life (t1/2), AUC(0-t) and CL showed no statistically significant differences; RA co-administration did not affect the pharmacokinetics of raltitrexed.
Animals ; Antineoplastic Agents ; administration & dosage ; pharmacokinetics ; Astragalus Plant ; chemistry ; Chromatography, High Pressure Liquid ; Drug Interactions ; Drugs, Chinese Herbal ; administration & dosage ; Female ; Humans ; Male ; Quinazolines ; administration & dosage ; pharmacokinetics ; Rats ; Rats, Sprague-Dawley ; Thiophenes ; administration & dosage ; pharmacokinetics

OBJECTIVE: Duloxetine hydrochloride is a selective serotonin (5-hydroxytryptamine) and norepinephrine reuptake inhibitor. It is approved for effective treatment for major depressive disorder. The pharmacokinetics (PK) of duloxetine has been studied, but few pharmacokinetics properties in Chinese subjects are available. This study explored the dose proportionality and determined duloxetine levels in human plasma by comparing the PK properties after administration of single or multiple doses in healthy volunteers. METHODS: Thirty-six subjects were divided randomly into three groups and received a single dose of 15, 30, or 60 mg duloxetine. Those who received 30 mg continued on to the multiple-dose phase and received 30 mg daily for 7 days. Liquid chromatography/mass spectroscopy was applied to determine concentrations. The PK properties were calculated and included maximum plasma concentration (Cmax), time when maximum plasma concentration was reached (Tmax), time when half-maximum plasma concentration was reached (t1/2), area under the plasma concentration-time curve from time zero to the last measurable concentration (AUC0-t), mean concentration levels (AUC0-infinity), and apparent total clearance of the drug from plasma after oral administration (CL/F). RESULTS: The standard calibration curve was linear in the concentration range 0.11-112 ng/ml (r>0.992). Linear PK properties were found at doses of 15-60 mg. The Cmax and AUC were proportional to dose, but the Tmax and t1/2 did not increase with increasing dose. CONCLUSION: No significant differences in the PK parameters were found among the three groups during the single-dose phase. The AUC and Cmax were greater in the multiple-dose phase, indicating duloxetine accumulation following multiple-dose administration.
Administration, Oral ; Area Under Curve ; Asian Continental Ancestry Group ; Calibration ; Depressive Disorder, Major ; Humans ; Norepinephrine ; Plasma ; Serotonin ; Spectrum Analysis ; Tablets, Enteric-Coated ; Thiophenes ; Duloxetine Hydrochloride

PURPOSE: To evaluate and compare the toxic effects of eyedrops containing a fixed combination of 2.0% dorzolamide and 0.5% maleate timolol with or without preservatives on rabbit corneal endothelium. METHODS: This study was performed with 22 eyes of New Zealand white rabbits. Dorzolamide/timolol eyedrops with preservative (Cosopt group) or without preservative (Cosopt-S group) were diluted with a balanced salt solution at a 1 : 1 ratio. We injected 0.1 mL of diluted Cosopt into the anterior chamber of left eyes and an equal volume of diluted Cosopt-S into the anterior chamber of right eyes. Corneal thickness, corneal haze, and conjunctival injection were measured before and 24 hours after treatment. Endothelial damage was compared between both eyes by vital staining (alizarin red/trypan blue staining), live/dead cell assay, TUNEL assay, and scanning electron microscopy. RESULTS: Corneal endothelial damage was severe in the Cosopt group. Cosopt-treated eyes exhibited remarkable corneal edema and prominent apoptosis of endothelial cells. In addition, the live/dead cell assay revealed many dead cells in the endothelium, and scanning electron microscopy analysis showed that corneal endothelial cells exhibited a partial loss of microvilli on the surface as well as extensive destruction of intercellular junctions. However, in the Cosopt-S group, corneal edema was mild and the damage to the corneal endothelium was minimal. CONCLUSIONS: The main cause of corneal endothelial toxicity was due to the preservative in the dorzolamide/timolol fixed combination eyedrops, and not the active ingredient. Thus, it appears to be safer to use preservative-free eyedrops during the early postoperative period.
Animals ; Anterior Chamber/drug effects ; Apoptosis ; Corneal Edema/chemically induced/*pathology ; Disease Models, Animal ; Drug Combinations ; Endothelium, Corneal/drug effects/*pathology ; In Situ Nick-End Labeling ; Ophthalmic Solutions ; Rabbits ; Sulfonamides/administration & dosage/*toxicity ; Thiophenes/administration & dosage/*toxicity ; Timolol/administration & dosage/*toxicity

A sensitive, rapid and accurate liquid chromatography-tandem mass spectrometric (LC-MS/MS) method with pre-column derivatization was developed for the simultaneous determination of erdosteine and its thiol-containing active metabolite in human plasma. Paracetamol and captopril were chosen as the internal standard of erdosteine and its active metabolite, respectively. Aliquots of 100 microL plasma sample were derivatized by 2-bromine-3'-methoxy acetophenone, then separated on an Agilent XDB-C18 (50 mm x 4.6 mm ID, 1.8 microm) column using 0.1% formic acid methanol--0.1% formic acid 5 mmol x L(-1) ammonium acetate as mobile phase, in a gradient mode. Detection of erdosteine and its active metabolite were achieved by ESI MS/MS in the positive ion mode. The linear calibration curves for erdosteine and its active metabolite were obtained in the concentration ranges of 5-3 000 ng x mL(-1) and 5-10 000 ng x mL(-1), respectively. The lower limit of quantification of erdosteine and its active metabolite were both 5.00 ng x mL(-1). The pharmacokinetic results of erdosteine and its thiol-containing active metabolite showed that the area under curve (AUC) of the thiol-containing active metabolite was 6.2 times of that of erdosteine after a single oral dose of 600 mg erdosteine tables in 32 healthy volunteers, The mean residence time (MRT) of the thiol-containing active metabolite was (7.51 +/- 0.788) h, which provided a pharmacokinetic basis for the rational dosage regimen.
Administration, Oral ; Area Under Curve ; Chromatography, Liquid ; Female ; Humans ; Male ; Spectrometry, Mass, Electrospray Ionization ; Tandem Mass Spectrometry ; Thioglycolates ; administration & dosage ; blood ; metabolism ; pharmacokinetics ; Thiophenes ; administration & dosage ; blood ; metabolism ; pharmacokinetics

This case report describes recurrent drug-eluting stent thrombosis with documented laboratory hyporesponsiveness to clopidogrel. The use of escalating doses of clopidogrel prevented subsequent episodes, but the patient developed gastrointestinal intolerance and diffuse cutaneous reaction, which resolved completely with prasugrel. Impressively, prasugrel 10 mg daily achieved an even lower vasodilator-stimulated phosphoprotein platelet reactivity index compared to clopidogrel 300 mg daily. Our case highlights the importance of alternative P2Y12 receptor antagonists for patients receiving drug-eluting stents.
Angioplasty, Balloon, Coronary ; Drug-Eluting Stents ; adverse effects ; Humans ; Male ; Middle Aged ; Myocardial Infarction ; therapy ; Piperazines ; therapeutic use ; Platelet Aggregation Inhibitors ; administration & dosage ; Prasugrel Hydrochloride ; Thiophenes ; therapeutic use ; Thrombosis ; drug therapy ; Ticlopidine ; administration & dosage ; analogs & derivatives ; Treatment Failure