Errors in prescription medication dosing are responsible for thousands of injuries and even deaths each year. A leading cause of these errors is tenfold medication prescribing errors, or errors involving adding an extra zero to the dosage amount on a prescription, so that the patient receives 10 times the intended dose of the drug.
Prescription Errors: Mistakes Can Cost Lives
Prescription medication errors can occur at all stages of the process, from the moment a physician writes the prescription to the point at which the patient takes the medicine. Some errors involve mixing up the names of similar-sounding medications; others are related to the misreading of abbreviations indicating the frequency of dosing. Many of these errors are minor and can be quickly resolved with minimal, if any, harm. But the so-called “zero,” or tenfold, errors have the potential to be lethal.
The dangers of tenfold prescribing errors entered public awareness in 2007, with a high-profile case involving the newborn twins of actor Dennis Quaid. According to reports by the Los Angeles Times and other sources, the children were given 10,000 units of the blood thinner heparin, rather than the prescribed 10 units. The Quaid children’s case was not an anomaly. According to a study of 200 incidences of tenfold medication errors reported by the US National Institutes of Health, 45% of the errors had severe consequences.
Tenfold Errors: Misplaced Decimals and Zeros
Tenfold prescribing errors are typically due to the addition of an extra zero to the dosage directions, so that a prescription for “55.0 mcg” might be read as “550 mcg.”
The problem can occur in reverse as well, with the omission of a zero that leads to a lower dose than prescribed. Other tenfold-type errors can be caused by a misplaced decimal point, or a decimal point that is not seen on a printed or handwritten order for the medication. For example, a prescription for “.55 mcg” could be read as “55 mcg.” Confusion between appropriate dosages for solid versus liquid forms of medications can also lead to tenfold dosage errors.
Acknowledging the prevalence of tenfold-type prescription errors, the pharmacy industry publication Pharmacy Times has recommended that prescribers always place a zero before a decimal point in order to call attention to it, such as “0.10mL” rather than “.10mL.” Omitting a “trailing zero” after the decimal point by writing “25” instead of “25.0” can also help to reduce confusion.
Medication errors can occur at all points in the prescribing process. But errors arising from an extra zero or a misplaced or misread decimal point are typically caused by prescribing physicians and healthcare professionals responsible for administering those medications. The risk of serious outcomes of these kinds of errors highlights the need for vigilance at all levels of prescription medication management.