Postgraduate medical journal
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Randomized Controlled Trial Clinical Trial
The effect of different nitrate preparations on plasma heparin concentrations and the activated partial thromboplastin time.
There is evidence that intravenous nitrates which are frequently used in acute coronary syndromes may interfere with the anticoagulant effect of heparin. We compared the effect of two different nitrate preparations on the activated partial thromboplastin time (APTT), anti-thrombin III activity (AT III) and plasma heparin levels in patients (n = 50) undergoing routine percutaneous transluminal coronary angioplasty (PTCA) for stable angina. Patients were randomized to either: (1) intravenous heparin and nitroglycerin (GTN); or (2) intravenous heparin and isosorbide dinitrate. ⋯ Within-group analysis showed significantly lower APTT ratio and heparin concentrations at 4 hours compared with the respective 2 hour values. These results would suggest that there is a potential impairment of anticoagulation with low-dose intravenous nitroglycerin and to a lesser extent with low-dose isosorbide dinitrate. Early and frequent monitoring may therefore be appropriate when intravenous nitrates and heparin are used in combination.
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Patients with chronic abdominal pain without an organic basis present a difficult management problem. Some of these patients may be prescribed opiates initially which may result in requiring progressively higher doses for pain relief. ⋯ With appropriate treatment and counselling, further invasive investigations including laparotomy may be avoided and resolution of symptoms can be achieved with clonidine. This case report demonstrates such a typical clinical scenario and discusses the possible aetiology and pathophysiology of narcotic bowel syndrome as well as the role of clonidine in controlling opiate withdrawal symptoms.