PubMed · 7697484
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B A Feigenbaum, R A Simon, D D Stevenson. 1995. Aspirin intolerance.. https://pubmed.ncbi.nlm.nih.gov/7697484/
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The aim of this study was to describe a competition between cytarabine (araC) and aspirin (ASA) in binding with bovine serum albumin (BSA). High-affinity binding sites for both drugs were determined using a spectrofluorimetric method. Cytarabine as well as aspirin binds in the IIA hydrophobic subdomain of the transporting protein. Binding constants for araC-BSA and ASA-BSA were calculated by the Scatchard method. Analysis of ultraviolet (UV) difference spectra showed that araC, which has a higher affinity to BSA in comparison to ASA [Ka(araC) > Ka(ASA)] displaces ASA in high-affinity binding sites. The competition between drugs in low-affinity binding sites was investigated using (1)H nuclear magnetic resonance (NMR) and 13C-NMR spectra. We concluded that in the low-affinity binding sites cytarabine decreases the affinity of albumin toward aspirin. However, the interaction between araC and BSA becomes more difficult in the presence of aspirin.
Thienopyridines and aspirin are beneficial in patients undergoing bare-metal stent implantation, and aspirin and clopidogrel treatment have also been proved effective after drug-eluting stent (DES) implantation. However, despite the common substitution of clopidogrel with ticlopidine because of cost or patient intolerance, there are no data on the comparison of ticlopidine vs. clopidogrel after DES implantation. We hereby compare ticlopidine vs. clopidogrel after paclitaxel-eluting stent implantation in subjects enrolled in the prospective multicenter Taxus in Real-life Usage Evaluation (TRUE) Study. Across the 505 analyzed patients (112 treated with ticlopidine and 393 with clopidogrel), similar rates of early and mid-term (7 months) adverse thrombotic events were found with either antiplatelet regimen, with the notable exception of 2 cases of late stent thrombosis in patients who had prematurely withdrawn ticlopidine treatment just 3 months after the procedure. These findings thus support the overall safety and effectiveness of ticlopidine after DES implantation, and also confirm the increased risk of late thrombosis when premature withdrawal of thienopyridines occurs.
A single ultrasonic relaxational phenomenon was observed in aqueous solutions containing both beta-cyclodextrin (beta-CD) as host and nonionized or ionized acetylsalicylic acid (aspirin) as guest. The observed relaxation was responsible for a dynamic complexation reaction between beta-CD and aspirin molecules, concomitant with a volume change during the reaction. The kinetic and equilibrium constants for the complexation in the acid (nonionized) form of the aspirin system were derived from the guest concentration dependence of the relaxation frequency. The equilibrium constant for the carboxylate (ionized) form of aspirin was determined from the concentration dependence of a maximum absorption per wavelength, and the rate constants were calculated by using the determined equilibrium constant and the observed relaxation frequencies, which remained nearly almost constant over the concentration range studied. The results showed that the effect of charge on the aspirin molecule was reflected only in the dissociation process from the beta-CD cavity, while no remarkable change was seen in the association process whose rate was diffusion controlled. The results could be explained on the basis of the difference of the hydrophobic moieties in the two guests that were included in the host cavity. The results of the standard volume change for the complexation reaction were closely related to the number of expelled water molecules originally located in the beta-CD cavity and the volume of the aspirin molecule incorporated into the beta-CD cavity.