Acetaminophen ( N-Acetyl-p-Aminophenol )
(APAP)
Sample type: -
Serum or plasma (heparin)
Uses: -
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Monitor therapeutic drug levels; evaluate for acetaminophen toxicity. Acetaminophen is as effective as aspirin when used for analgesia and antipyresis. It is used to treat headache, mild-to-moderate myalgia, arthralgia, chronic pain of cancer, postpartum pain, postoperative pain, and fever. The ceiling analgesic effect is obtained with a dose of 1 g.
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Acetaminophen is the preferred alternative to aspirin for patients who cannot tolerate the latter, those with a coagulation disorder, or individuals with a history of peptic ulcer or reflux esophagitis.
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In children requiring only analgesia or antipyresis, acetaminophen may be preferred to aspirin because it is less toxic if an accidental overdose occurs. (Interestingly, acetaminophen overdosage in children younger than six years is rarely, if ever, associated with hepatotoxicity, but such protection is lost by adolescence.)
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Acetaminophen is unsatisfactory for conditions requiring potent anti-inflammatory activity (rheumatic disease, juvenile arthritis, dysmenorrhea, sunburn). Unlike aspirin, acetaminophen does not antagonize the effects of uricosuric agents and may be used in patients with gouty arthritis who are taking a uricosuric.
Precaution: -
There are no specific precautions needed.
Interfere action: -
- Screening
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Serum/urine: colorimetric or immunoassay on automated chemistry analyzers.
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High bilirubin concentrations [>50 μg/mL] may cause false-positive results with immunoassay-based tests.
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Plasma may be tested in place of serum. Anticoagulants such as EDTA and heparin do not generally interfere with the assay.
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Do not use whole blood.
- Confirmation:
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Serum/urine–HPLC or GC/MC.
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APAP is highly conjugated by glucuronidation and sulfation.
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An assay that includes a hydrolysis step provides total APAP levels, which are not useful for assessing toxicity.
Pre analytical error: -
- Long time use of the tourniquet or arm upward position while collecting blood.
Corrective action: -
- You should collect the blood with the correct way in the next time and if another person will analyze this sample, you should tell him to expect if there is an increase in the result.
Post analytical action: -
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Reports were sent to the incorrect patient.
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Write the wrong name in the report or the wrong results.
Corrective action: -
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Communicate with patient, apologizing for the error, and providing him with the correct report.
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If the report is not delivered to the patient and this error is discovered, the correct result or the correct name must be written, but if the report is delivered to the patient, you must communicate with him, apologize to him, and tell him that an error has occurred and replace it with the correct report.
Reference range: -
Normal range: 5–20 μg/mL serum
Potentially toxic: >150 μg/mL measured 4 hours post dose