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The Mayfield Handbook of Technical & Scientific Writing
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Examples of Document Density

The following two passages illustrate differences in the amount, type, detail, complexity, and rate of information appropriate to the two different audiences, one expert and one general. Both passages describe possible adverse side effects of the commonly prescribed allergy drug terfenadine (brand name Seldane).

The first passage is excerpted from the Physicians' Desk Reference, the standard guide to prescription drugs used by medical doctors in the United States. To ensure their patients' health, doctors have a professional, ethical, and legal obligation to know the specific information contained in this work about any drug they prescribe. The second passage is taken from the The Pill Book, a popular consumer guide for prescription drugs. This document is designed for laypersons with little technical medical knowledge. The laypersons' purpose in using the book is to become more knowledgeable about the specific drugs they may take and to become aware of any potential dangers.


Terfenadine undergoes extensive metabolism in the liver by a specific cytochrome P-450 isoenzyme. This metabolic pathway may be impaired in patients with hepatic dysfunction (alcoholic cirrhosis, hepatitis) or who are taking drugs such as ketoconazole, itraconazole, or clarithromycin, erythromycin, or troleandomycin (macrolide antibiotics), or other potent inhibitors of this isoenzyme. Interference with this metabolism can lead to elevated terfenadine plasma levels associated with QT prolongation and increased risk of ventricular tachyarrhythmias (such as torsades de pointes, ventricular tachycardia, and ventricular fibrillation) at the recommended dose. SELDANETM is contraindicated for patients with these conditions (see WARNING BOX, CONTRAINDICATIONS, and PRECAUTIONS: Drug Interactions).

--Physicians' Desk Reference

Because the foregoing document is written for experts who will be using the information for what may be life-or-death decisions, the information provided is extensive. The document describes in detail the biological processes that make the drug dangerous to patients with liver problems and lists the two specific liver diseases that should deter doctors from prescribing the drug. Similarly, the passage gives an exhaustive list of all drugs that might cause specific heart problems. Because the document is intended for experts familiar with medical jargon, technical terms such as isoenzyme and ventricular tachycardia are used without any explanation.

Cautions and Warnings

In rare cases, terfenadine may cause serious adverse heart rhythms or other cardiac events. It should be taken with care by people with serious liver disease and by those taking erythromycin, ketoconazole, or itraconazole. . . . Dizziness or fainting may be the first sign of a cardiac problem with terfenadine.

--Harold S. Herman, ed. The Pill Book

The technical terms of the first passage, such as ventricular tachyarrhythmias, are replaced by more accessible but less precise terminology such as serious adverse heart rhythms. This passage reduces the list of drugs that may interact dangerously with terfenadine to the few drugs that would most likely be taken by readers of the book. Finally, because a principal use of the book is to allow consumers to identify possible dangerous drug reactions, the passage lists for the reader the most common symptoms of ventricular tachyarrhythmias: dizziness or fainting.

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## Examples of Document Density ##
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