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Medication dosing challenges in the paediatric population
An article for physicians by physicians
Originally published March 2010
P1001-2-E

Although adverse events related to medications can happen in the treatment of patients of all ages, paediatric patients present unique challenges as physicians must calculate dosages for each patient individually.

The CMPA reviewed all medico-legal cases opened or closed between 1998 and 2008 that were associated with medication use and involved children from birth to 18 years of age. A total of 128 cases were reviewed, of which 111 were closed. (The review excluded cases involving fluid and electrolyte replacement and obstetrical cases in which the medication issue was related to the mother’s care.)

Identified themes

An analysis of the 111 closed medico-legal cases revealed six principal issues with the use of medication in children, which are outlined below in order of frequency:

• The wrong dose of medication was prescribed or administered.
• Another health care professional incorrectly dispensed or administered a prescribed medication.
• The patient was inadequately evaluated before medication was prescribed.
• A contraindicated medication was prescribed, most often when the patient had a documented allergy or the use of the medication was controversial for children or adolescents.
• There was a delay or failure to prescribe or administer a medication.
• A medication was administered or applied that then harmed the patient, most often a burn from a topical agent, e.g., cantharidin or liquid nitrogen.

Prescribing or administering the wrong dose of a medication was the predominant theme in the 111 closed cases. Most of the medico-legal problems involving a medication dosage issue were caused by incorrect prescribing by the physician. In many of these cases, other health care professionals were involved in the medication process (e.g., pharmacists and nurses) but did not detect that the prescription or medication order specified an inappropriate dose of medication and therefore dispensed or administered the incorrect dose. These adverse events took place in a variety of locations including hospitals, e.g., paediatric and community, and physicians’ offices.

The following cases illustrate some of the situations where the wrong dose of medication may be prescribed or administered to a child.

Case examples

Misinterpretation of medication information

An alert five-month-old infant, weighing 7 kg, presented to the emergency department (ED) of a paediatric hospital with severe urticaria, diffuse expiratory wheezing, and early oropharyngeal edema with slight swelling of the tip of the tongue. Suspecting an allergic reaction, the paediatrician prescribed 0.7 ml epinephrine [1:1,000] subcutaneously (s/c). The urticaria improved and the wheezing disappeared.

Fifteen minutes later, the urticaria alone recurred and the infant vomited. The same dose of epinephrine was repeated s/c in addition to the intravenous (IV) administration of an antihistamine and a corticosteroid.

When the urticaria reappeared yet again 15 minutes later, the paediatrician ordered 0.7 ml of epinephrine [1:1,000] IV. The registered nurse questioned the dose, so the paediatrician verified the recommended dose in the departmental epinephrine dosing algorithm. However, he misinterpreted the information provided in the treatment guideline and again instructed the nurse to administer the incorrect dose. The nurse administered the prescribed dose as directed.

Shortly thereafter, the infant arrested. Resuscitative measures failed. The autopsy findings were more consistent with a catecholamine excess than anaphylactic shock.

Experts concurred that the infant presented with an acute allergic reaction and epinephrine was the drug of choice in this situation. However, the experts stated the s/c epinephrine doses were 10 times the recommended dose, and the IV epinephrine dose administered was not only excessive but was also not indicated in this case in the absence of more severe symptomatology. One of the experts further recommended that physicians prescribing epinephrine should be mindful that “epinephrine doses, concentrations and routes of administration differ depending on the disorder being treated.  . . . A careful verification of the appropriate epinephrine dose, . . . the epinephrine concentration and the route of administration should be performed.”

Improper correction of a written order

A one-week-old infant was admitted to a small community hospital for investigation of a two-day history of poor feeding and lethargy. The family practice resident diagnosed probable sepsis. After discussing the infant’s clinical condition and treatment plan with the staff physician, the resident prescribed ampicillin 250 mg IV every six hours and gentamicin 75 mg IV every eight hours. He immediately realized the doses for both antibiotics were too high and modified them by writing over the original order. In doing so, the decimal point for the corrected gentamicin dose of 7.5 mg was not obvious. He also did not notify anyone of his corrections. Neither the nurse nor the pharmacist detected the decimal point on the gentamicin order. The infant subsequently received two doses of gentamicin 75 mg before the error was identified. The resident promptly disclosed this adverse event to the parents. A temporary increase in the infant’s creatinine levels resulted, but there were no long-term sequelae.

Caution when converting a medication dose to a suspension volume

An ED physician in a teaching hospital prescribed a macrolide antibiotic for an infant with otitis media. He correctly wrote the intended dose in the emergency medical record. However, he incorrectly calculated the volume of suspension required and prescribed a volume equivalent to five times the intended dose. The infant received only one incorrect dose of antibiotic before attending the usual paediatrician who amended the prescription. The mother reported the infant experienced loose stools for two days following this incident.

Misunderstanding recommendations for divided medication doses

A newborn, who had been delivered at term 24 hours prior, developed tachypnea. The treating family physician consulted a paediatrician by telephone. The paediatrician recommended starting IV gentamicin and ampicillin while awaiting blood culture results. He recommended the gentamicin be given in divided doses 12 hours apart (q12h) for a total daily dosage of 5 mg/kg/day. However, the family physician misunderstood the paediatrician’s instructions and prescribed the total daily dose q12h. The newborn received three doses before the dose was corrected following transfer to another institution. No gentamicin-related ototoxic or nephrotoxic sequelae ensued.

Identified safety measures

Experts in the closed medico-legal cases were of the opinion that certain adverse events related to medications might have been prevented had the physician:

• researched unfamiliar medications
• based the medication dosage on the patient’s current weight
• used legible handwriting when writing the medication order/prescription
• double-checked a medication dose calculation
• tapered the dosage before discontinuing the medication, when indicated
• labelled medications clearly
• documented the administration of a medication
• provided clear patient instructions when an existing prescription was modified
• monitored the efficacy of a medication, identified potential adverse effects or re-evaluated the child’s condition before renewing a prescription

Managing medico-legal risks

The following risk management considerations are based on the expert opinions in the analyzed cases:

• Have you calculated individual doses based on the child’s weight or body surface area and clinical condition?
• Are medication reference materials or treatment algorithms readily available and is the information current and clear?
• Are consultant recommendations clear, particularly when divided medication doses are indicated?
• Have you verified the medication, dose calculation, solution concentration and route of administration?
• Have you considered other health care professionals’ concerns about a medication dose?
• Are your prescriptions legible?
• If a change is required to an existing medication order, whether handwritten or by computer order entry, have you made the correction according to established documentation principles?
• Have you monitored the efficacy of a medication, identified potential adverse effects or re-evaluated the child’s condition before renewing a prescription?
• Are your medical records accurate, up-to-date and contemporaneous?
• Have you appropriately and accurately labelled and stored medications?