Acetaminophen contraindications

Discuss the types, uses, general drug actions, common adverse reactions, contraindications, precautions, and interactions of the salicylates and acetaminophen. 

It has been suggested that a loading dose (twice the usual single dose) of the NSAID be taken, followed by the usually recommended dose until symptoms resolve.28 An alternate recommendation is to begin the NSAID at the onset of menses or perhaps even the day prior and to continue treatment around the clock instead of waiting until the onset of symptoms. For patients in whom NSAID use is contraindicated, the agents discussed below should be considered. The use of acetaminophen has been proven inferior to the use of NSAIDs for the treatment of this disorder.17... 

Tramadol is a reasonable option for patients with contraindications to NSAIDs or failure to respond to other oral therapies. For the treatment of hip or knee OA, tramadol is as effective as NSAIDs. The addition of tramadol to NSAIDs or acetaminophen may augment the analgesic effects of a failing regimen, thereby securing sufficient pain relief in some patients. Moreover, concomitant tramadol may permit the use of lower NSAID doses. 

Fever, rigors, chills, malaise headaches, myalgia Nausea, emesis Neutropenia Hepatic enzyme elevation Cutaneous—alopecia, transient, mild rashlike reaction Acetaminophen (APAP). NSAID if APAP is not effective. Meperidine for severe chills and rigors. Bedtime administration. 5-HT3 antagonist, prochlorperazine, metoclopramide, fluids Weekly complete blood count reduce dose by 30-50% Liver function tests (LFTs) weekly withhold treatment until LFTs normalize restart at 30-50% dose reduction reversible on dose reduction or cessation. Interferon is contraindicated in patients with psoriasis because exacerbation of psoriasis has been noted during IFN therapy. 

Contraindications Glaucoma, hypersensitivity to acetaminophen, isometheptene, dichloralphenazone, or any component of the formulation, hepatic disease, hypertension, organic heart disease, MAO inhibitor therapy, severe renal disease... 

The most important contraindications to salicylate therapy are listed in Box 7-1. As a general rule, when aspirin is contraindicated or is not well tolerated, acetaminophen... 

Contraindications fc>r nonsalicylate NSAID therapy are the same as those for aspirin (see Box 7-I).The formation of a gastric ulcer or erosion that may bleed profusely is a serious potential problem with NSAIDs. Consequently, the nonsalicylate NSAIDs should be avoided or used with great caution in patients with active peptic ulcer disease. NSAIDs may increase the risk of GI complications even when used in conjunction with low-dose aspirin for cardioprotection. In addition, because of potential crosssensitivity to other NSAIDs, the nonsalicylate NSAIDs should not be given to patients in whom aspirin or other NSAIDs have caused symptoms of asthma, rhinitis, urticaria, angioedema, hypotension, bronchospasm, or of symptoms of hypersensitivity reactions. Opioids, tramadol, or acetaminophen may be suitable alternatives for patients with known or suspected susceptibility. 

The presence of prilocaine is a (relative) contraindication to combining EMLA with products with a potential to cause methemoglobinemia. Combined use with paracetamol (acetaminophen), for example, is to be avoided. Paracetamol is a derivative of phenol (N-acetyl-para-aminophenol) and is subject to the same detoxification pathways as phenol. Paracetamol inherits its properties of causing methemoglobinemia from phenol. Large doses of EMLA (>600 mg of prilocaine, or four 5 g tubes) should therefore not be applied prior to phenol. 

Phenacetin has analgesic and antipyretic but no antiinflammatory properties. Phenacetin and its deethylated metabolite, acetaminophen, are superior to aspirin in that they do not cause hypoprothrombinemia, GI irritation, or disturbances of acid-base balance. The serious, but rare, side effects of phenacetin are methemoglobinemia, hemolytic anemia, fatal hepatic necrosis, and hypoglycemic coma. Both interstitial nephritis and renal papillary necrosis can be caused by phenacetin and acetaminophen. The less toxic acetaminophen should be used only in patients who cannot tolerate aspirin or in whom aspirin is contraindicated (see also Table 3). 

Acetaminophen is a suitable substitute for aspirin for analgesic or antipyretic uses it is particularly valuable for patients in whom aspirin is contraindicated (e.g., those with peptic ulcer, aspirin hypersensitivity, children with afebrile illness). The conventional oral dose of acetaminophen is 325-1000 mg (650 mg rectally) total daily doses should not exceed 4000 mg (2000 mg/day for... 

For routine post-operative analgesia, we rely on acetaminophen, local anesthetics, NSAIDS if not contraindicated, and, finally, opiates. Even if pain control is adequate without opiates, small doses of fentanyl may be used at the time of emergence to ease a patient through emergence delirium and the first moments in PACU when even parental presence is not a comfort... 

Absolute intravenous acetaminophen is absolutely contraindicated in patients in fulminant hepatic failure. 

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