Inhibition of antiplatelet effects of aspirin by nonopioid analgesics

[Pharmacology of non-opioid analgesics]

Due to high prescription rates as well as the frequent use as over the counter drugs, it is of interest to consider non-opioid analgesics when evaluating the quality and appropriateness of a given overall medication. This article sums up the basic pharmacology and main adverse effects of these analgesics. Non-opioids can be further classified according to their additional mechanisms of action besides analgesia. High-dose acetylsalicylic acid, traditional nonsteroidal anti-inflammatory drugs, and coxibs exhibit antipyretic and anti-inflammatory properties. Acetaminophen and metamizole (dipyrone) are analgesics and antipyretic agents, while metamizole exhibits also spasmolytic effects. Capsaicin and intrathecal ziconotide are pure analgesics.

Antiplatelet Effect of Ketorolac in Children After Congenital Cardiac Surgery

Background:

Ketorolac is used for pediatric analgesia after surgery despite its known platelet inhibition via the arachidonic acid (AA) pathway. The degree of platelet inhibitory effect after cardiac surgery is not well characterized. Thromboelastography with platelet mapping (TEG-PM) is emerging as a frequently used test to evaluate platelet inhibition via the AA pathway.

Methods:

Post hoc analysis of a data set collected in a prospective observational cohort study evaluating platelet inhibition in children after congenital heart surgery with cardiopulmonary bypass (CPB). Categorization into two groups: (1) received ketorolac and (2) did not receive ketorolac for analgesia after surgery. The TEG-PM was evaluated at two time points (prior to surgery and 12-48 hours after CPB).

Results:

Fifty-three children were studied; mean age was 6.6 (range: 0.07-16.7) years and 45% (n = 24) were female. Participants were distributed into two groups by ketorolac use, 41 within the ketorolac group and 12 in the no ketorolac group. All 41 participants who received ketorolac had platelet inhibition and 11 (91.7%) of 12 participants who did not receive ketorolac had normal platelet function after surgery ( P < .0001). There was no difference in patient characteristics or clinical data between the two groups.

Conclusions:

Ketorolac use in a cohort of children after congenital cardiac surgery was associated with platelet inhibition via the AA pathway when evaluated by TEG-PM.

Studying additive interaction in a healthcare database: Case study of NSAIDs, cardiovascular profiles, and acute myocardial infarction

Purpose

There are clinical trial data on risk of acute myocardial infarction (MI) with nonsteroidal anti-inflammatory drugs (NSAIDs) in patients at increased cardiovascular (CV) risk requiring chronic daily treatment. This study investigated whether risks of acute MI with real-world prescription NSAIDs, such as low-dose or intermittent use, vary according to an individual’s CV profile.

Methods

Nested case-control analyses were carried out on an administrative health cohort from Quebec, Canada by randomly selecting 10 controls per case matched on age ± 1 year, sex, and month and year of cohort entry. We measured the additive joint effects on acute MI of current NSAID use and presence of hypertension, coronary heart disease (CHD), history of previous MI, or concomitant use of cardioprotective aspirin. The endpoint was the relative excess risk due to interaction (RERI). To verify the robustness of interaction findings, we performed sensitivity analyses with varying specifications of NSAID exposure-related variables.

Results

The cohort consisted of 233 816 elderly individuals, including 21 256 acute MI cases. For hypertension, CHD, and previous MI, we identified additive interactions on MI risk with some but not all NSAIDs, which also depended on the definition of NSAID exposure. Hypertension was sub-additive with naproxen but not with the other NSAIDs. Celecoxib and CHD were sub-additive in the primary analysis only (modelling NSAID dose on index date or up to 7 days before–best-fitting base model) whereas celecoxib and rofecoxib were super-additive with a history of previous MI in the secondary analysis only (modelling NSAID use on index date). For cardioprotective aspirin we found no evidence for an additive interaction with any of the NSAIDs.

Conclusions

Alternative specifications of NSAID exposure concurred in finding that concomitant use of cardioprotective aspirin does not attenuate the risks of acute MI with NSAIDs. However we were unable to demonstrate consistent interactions between an individual’s cardiovascular comorbidities and NSAID-associated acute MI. Our study highlights challenges of studying additive interactions in a healthcare database and underscores the need for sensitivity analyses.

The influence of environmental variables on platelet concentration in horse platelet-rich plasma

Platelet-rich plasma (PRP) commonly refers to blood products which contain a higher platelet (PLT) concentration as compared to normal plasma. Autologous PRP has been shown to be safe and effective in promoting the natural processes of soft tissue healing or reconstruction in humans and horses. Variability in PLT concentration has been observed in practice between PRP preparations from different patients or from the same individual under different conditions. A change in PLT concentration could modify PRP efficacy in routine applications. The aim of this study was to test the influence of environmental, individual and agonistic variables on the PLT concentration of PRP in horses. Six healthy Standardbred mares were exposed to six different variables with a one-week washout period between variables, and PRP was subsequently obtained from each horse. The variables were time of withdrawal during the day (morning/evening), hydration status (overhydration/dehydration) treatment with anti-inflammatory drugs and training periods on a treadmill. The platelet concentration was significantly higher in horses treated with a non-steroidal anti-inflammatory drug (P = 0.03). The leukocyte concentration increased 2–9 fold with respect to whole blood in the PRP which was obtained after exposure to all the variable considered. Environmental variation in platelet concentration should be taken into consideration during PRP preparation.