Enhancement of antithrombotic effect of aspirin by metoclopramide in rats

Do We Really Need Aspirin Loading for STEMI?

Aspirin loading (chewable or intravenous) as soon as possible after presentation is a class I recommendation by current ST elevation myocardial infarction (STEMI) guidelines. Earlier achievement of therapeutic antiplatelet effects by aspirin loading has long been considered the standard of care. However, the effects of the loading dose of aspirin (alone or in addition to a chronic maintenance oral dose) have not been studied. A large proportion of myocardial cell death occurs upon and after reperfusion (reperfusion injury). Numerous agents and interventions have been shown to limit infarct size in animal models when administered before or immediately after reperfusion. However, these interventions have predominantly failed to show significant protection in clinical studies. In the current review, we raise the hypothesis that aspirin loading may be the culprit. Data obtained from animal models consistently show that statins, ticagrelor, opiates, and ischemic postconditioning limit myocardial infarct size. In most of these studies, aspirin was not administered. However, when aspirin was administered before reperfusion (as is the case in the majority of studies enrolling STEMI patients), the protective effects of statin, ticagrelor, morphine, and ischemic postconditioning were attenuated, which can be plausibly attributable to aspirin loading. We therefore suggest studying the effects of aspirin loading before reperfusion on the infarct size limiting effects of statins, ticagrelor, morphine, and/ or postconditioning in large animal models using long reperfusion periods (at least 24 h). If indeed aspirin attenuates the protective effects, clinical trials should be conducted comparing aspirin loading to alternative antiplatelet regimens without aspirin loading in patients with STEMI undergoing primary percutaneous coronary intervention.

A Large Discrepancy between Oral versus Rectal Temperatures as an Early Warning Sign in a Patient with Acute Infrarenal Aortic Occlusion

BACKGROUND

Acute aortic occlusion is a rare condition that requires early diagnosis to help prevent considerable morbidity and mortality. Typical clinical findings, such as acute lower extremity pain, acute paralysis, and absent pedal pulses, may be masked by a variety of underlying medical conditions.

CASE REPORT

We present a patient with altered mental status, hypothermia, and a large discrepancy between oral and rectal temperature measurements, who was ultimately diagnosed with aortic occlusion. This case report describes a marked difference between oral and rectal temperatures in a case of acute aortic occlusion. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Acute aortic occlusion is a true vascular emergency that, without early intervention, can lead to limb ischemia, bowel necrosis, paralysis, or death. Emergency physicians should consider acute aortic occlusion in a patient with a marked difference between oral and rectal temperature measurements who otherwise has a limited clinical evaluation.

Intra-arterial injection of metoclopramide, midazolam, propofol and pethidine

A case is reported in which metoclopramide, midazolam, propofol, and pethidine were injected arterially during the course of anaesthesia, resulting in oedema and discolouration of the hand initially, but no long-term sequelae. An AVI 470 pump (3M Corporation) was used to control the infusion, andprevented backflow through a cannula which was unintentionally sited in an artery rather than a vein. Few anaesthetic drugs have their effects well documented when given arterially, and in particular, there were no previous reported cases involving metoclopramide in this context. The pharmacology of metoclopramide is discussed with reference to the drug's known effects on vascular beds and platelet function.

Combination of aspirin and metoclopramide produces a synergistic antithrombotic effect in a canine model of coronary artery thrombosis

We compared the antithrombotic properties of low doses of aspirin (0.03, 0.1 mg kg-1 intravenously [iv]) and metoclopramide (0.1, 0.3 mg kg-1 iv) alone or in combination. The animal model chosen for this study involved the generation of cyclic flow variations (CFV) in the circumflex coronary artery of anaesthetized dogs as a result of a critical coronary stenosis associated with a controlled arterial lesion at the site of stenosis. Subsequent regular CFV represent sequential thrombus formation and embolization in the damaged vessel. Neither aspirin nor metoclopramide alone demonstrated antithrombotic properties at the doses tested. However, the combination of aspirin 0.1 mg kg-1 i.v. and metoclopramide 0.3 mg kg-1 i.v. produced a significant antithrombotic effect, reducing the frequency of large CFV from 6.7 +/- 0.5 to 0.8 +/- 0.4 cycles h-1 (P < 0.01) and increasing minimum mean coronary blood flow from 5.0 +/- 1.1 to 23.7 +/- 2.6 mL min-1 (P < 0.01). This result apparently reflects an antithrombotic synergism between aspirin and metoclopramide since the effects of the combination were greater than the combined effects of the individual treatments. The antithrombotic influence of metoclopramide could be due to its 5HT2-antagonist or alpha 2-antagonist properties, both of which would inhibit platelet aggregation. This demonstration of a synergistic antithrombotic action of the combination of aspirin and metoclopramide is of interest since these two agents are often combined in clinical use. Its therapeutic relevance, however, remains to be established.