This article is more than 5 years old. Information may no longer be current.
Medication dosing devices
Several types of liquid medication dosing devices are available. This month’s column will review their unique characteristics.
When a prescription for a liquid medication is given to a caregiver, clinicians may not ponder the implications of understanding by the caregiver of proper measurement of a dose. After all, how hard is measurement and administration of one teaspoonful? In reality, numerous errors can be made when administering such doses. Because infants and young children often require liquid medication, problems and errors inherent in measuring and administering liquids may occur.
Available dosing devices
Devices generally available for measuring and administering liquid medications include teaspoons or tablespoons (tableware), medicine cup, calibrated medicine spoon, calibrated oral medicine dropper, oral dosing syringe, injectable syringe and the Rx medibottle (The Medicine Bottle Co.). Tableware commonly found in a home kitchen should not be used in measuring liquid medications, as they may not accurately measure the standard teaspoonful amount — 5 ml. These devices are likely to be the most inaccurate dosing devices. Studies have revealed that tableware teaspoons can vary between 2.5 ml to 7.8 ml. The AAP cautioned on the use of tableware teaspoons as liquid medication dosing devices in 1975.
|
Medicine cups are commonly used as measuring devices, and they often are attached to over the counter (OTC) products. Medicine cups may not accurately measure small liquid doses (<15 ml). It may also be difficult to administer the full dose of a viscous liquid from a medicine cup. An interesting study published in 1992 by Litovitz evaluated reports to U.S. poison centers over an eight-day period involving medication errors associated with the use of medicine cups. Thirty-four cases were reported by 16 poison centers; 79% involved two- to three-fold dosing errors. Three major causes of errors included confusion between teaspoons and tablespoons, assumption that the medicine cup was the unit of measure, and assumption that the full medicine cup was the actual dose. Causes of confusion for teaspoon vs. tablespoon may include confusion over their abbreviations (eg, tsp vs. tbsp) or difficulty reading the markings on the medicine cup. Additionally, one case involved confusion over teaspoons vs. milliliters (eg, 2 tsp given vs. 2 ml). Extrapolating these results to the total population served by the reporting poison centers, the researchers estimated that more than 7,000 medicine cup-related dosing errors are reported to poison centers annually.
Graduated medicine spoons may also be used by caregivers and are likely to be more accurate than tableware devices. However, it may be difficult to administer the full dose of viscous liquids. Oral medicine droppers may accurately measure doses, although difficulty may be encountered as well administering viscous liquids. Oral medicine syringes are often the preferred dosing instrument, as they are accurate and allow administration of the full dose of viscous liquids. Disadvantages of oral syringes include the potential for inappropriate placement and drug delivery in the infant’s or child’s mouth, which may result in choking or gagging. Correct administration of an oral syringe includes placement of the syringe tip near the back, inside cheek. The liquid medication should not be placed directly in the back of the mouth as this may result in choking or aspiration. Syringes intended for delivery of injectable medications may also be used to dose oral medications, when the needle is removed. An important concern with use of either syringe device involves potential choking of the syringe cap when caregivers have neglected to remove the cap prior to use. Several such incidents have been reported. The FDA has recognized this concern and has communicated with syringe manufacturers to reduce this potential adverse effect by eliminating caps from oral dosing syringe packaging. However, some oral dosing syringes may still be available with caps, which can be used to prevent leakage. When injectable syringes, which contain caps, are used as dosing devices, it is imperative that caregivers be instructed to throw out the cap prior to use, or if preparing stored doses, to be aware of choking potential. Caregivers may also choose to administer liquid medications, especially those with poor taste or acceptance in the infant’s nutritional formula bottle. Considerations for administering medications in this manner include: physical or chemical compatibility of the drug with the nutritional formula or liquid used, knowledge of the effects of food in the stomach on the drug’s absorption, and the concern of complete dosing if the entire contents of the bottle are not ingested.
A relatively new dosing device intended for dosing liquid medications in infants is the Rx medibottle. The Rx medibottle is shaped similarly to a typical infant nutritional formula bottle (holding approximately 100 ml), with standard nipple and collar, and additionally contains an internal sleeve which holds a 3 ml or 5 ml oral dosing syringe, inserted into the bottom of the bottle. While the infant sucks on the nipple to feed, the caregiver slowly depresses the syringe plunger to yield short squirts of medication for every one to four sips by the infant. The liquid medication mixes with the nutritional formula in the nipple. Kraus compared the Rx medibottle with a standard oral syringe in dosing acetaminophen syrup (160 mg/5 ml) in an open-label, randomized, crossover study to 30 infants (2 to 14 months of age). Each infant received a single dose of acetaminophen, with 50% of the dose given by each dosing method. The primary outcome measures were effectiveness of drug delivery and infant acceptance (as scored by three raters). More infants received the entire intended dose by the Rx medibottle as compared to syringe administration (P<0.05). Infant acceptance was also greater with the Rx medibottle (P<0.05). Disadvantages of the Rx medibottle included an increased time for dosing (71 seconds vs. 22 seconds for syringe dosing). An additional disadvantage includes an inability of several medications to flow appropriately through the syringe tip: Children's Tylenol suspension and infant drops, clarithromycin (Biaxin, Abbott), cefuroxime axetil (Ceftin, GlaxoSmithKline), and nelfinavir suspension (Viracept). Acetaminophen elixir products are compatible with the Rx medibottle. Compatibility of the drug intended for administration with the intended liquid (eg, milk, formula or other) should be verified prior to use. The cost of the Rx medibottle is approximately $8.
Several dosing devices are available to caregivers to administer liquid medications. Each device has advantages and disadvantages. Common tableware should not be used to dose liquid medications, as they are not likely to be accurate. Studies have shown that some caregivers continue to use tableware to dose liquid medications. Syringes are often the preferred dosing devices, as they are easy to use and are accurate. It is important that appropriate counseling on cap-removal be given to caregivers prior to use. The Rx medibottle can effectively be used to administer many liquid medications to young infants.
Appropriate counseling and education of caregivers about dosing technique is also important. Studies have revealed that caregivers may confuse: ml with mg, tsp with ml, or tsp with tbsp. Some caregivers have also assumed that the correct dose for a child is the total fill volume of the medication cup available with the product, or that medication cups from different products are equivalent and interchangeable.
Clinicians should specify drug dosage amounts – the weight dose (eg, mg) and the volume dose (eg, ml) – when prescribing medications (Rx or OTC). Use of measured volume doses (eg, ml) is preferable to doses expressed as teaspoons or tablespoons, as the latter may imply it is appropriate to use tableware devices.
|
|
For more information:
- Committee on Drugs, American Academy of Pediatrics. Inaccuracies in administering liquid medication. Pediatrics. 1975;56:327-328.
- Botash AS. Syringe caps: an aspiration hazard. Pediatrics. 1992;90:92-93.
- Litovitz T. Implication of dispensing cups in dosing errors and pediatric poisonings: a report from the American Association of Poison Control centers. Ann Pharmacother. 1992;26:917-8.
- Kraus DM. Effectiveness and infant acceptance of the Rx medibottle versus the oral syringe. Pharmacotherapy. 2001;21:416-423.
- Kurtzweil P. Avoiding problems: liquid medication and dosing devices. FDA Consumer. 1994 October.