Episode Transcript
Hi and Welcome to Clerkship Ready - Pediatrics - A podcast aimed at helping you excel during your clinical clerkship in Pediatrics.
I’m Dr. Rachel Moon, and I am a Professor of Pediatrics at the University of Virginia School of Medicine. Today we’re going to talk about what you need to know before you prescribe medications for the pediatric population. We talk about choosing antibiotics in a separate podcast episode, so be sure and check that episode out as well.
Let’s start with some general information.
1. When you prescribe medications in pediatrics, it’s not like in adult medicine. You can’t just give everyone the same dose. Check with your attending or resident to see which reference you should use to look up pediatric drug doses and frequencies. Commonly used references include Up to date, the Harriet Lane handbook and Lexicomp. I’ve included the links in the Show Notes. You can and should consider downloading an app on your phone for medication dosing to make looking this up easy in a busy day workflow. Check with your institution, because they may have one or more of these references available free to medical students.
2. In pediatrics, many medication doses are weight-based – usually in units of mg/kg. If you work at a place that measures weights in pounds, you will have to convert that to kilograms. 1 kg = 2.2 pounds. Often your electronic medical record system will do that for you. If not, then your calculator will be your best friend! If you have to do the calculations in your head, you can divide the pounds by 2, and then subtract an additional 10%.
3. However, it’s also not as simple as just doing mg/kg. You will have to look to see what the maximum daily dose – or the adult dose- is, particularly in older children and teenagers as they may be above the daily maximum does if you do it strictly by mg/kg. Even for young children, if they have a high weight you may be at a dangerous dose, so get in the habit of always checking maximum daily dosing. This is also true with IV fluids – you wouldn’t give a child more in the way of maintenance fluids than you would an adult. Similarly, you don’t want to give your patient a dose that is higher than what an adult would get.
4. Most pediatric medications come in intravenous (IV), intramuscular (IM), and/or oral (PO) formulations. There are also some medications that are used locally – like ear, eye, or nose drops; topical ointments, or aerosolized medications – for instance, inhalers for asthma. Some medications also come in rectal (PR) form, but we use these mainly in emergencies. For instance, if someone is in status epilepticus, PR diazepam may be used. Acetaminophen, or Tylenol, rectal suppositories are the other most commonly used PR medications.
5. For inpatients, you can give any of these formulations. We tend not to use IM medicines too much, because they are more painful and more emotionally traumatic for children. For those who cannot tolerate PO medicines – for instance, if they are vomiting – we usually give them IV medicines. However, for most children, you will want to transition them to PO medications before they are discharged. Some children who need to have IV medications for extended periods of time but are otherwise ready for discharge may have to have home IV therapy. For example, a child with osteomyelitis caused by methicillin-resistant Staph aureus (MRSA) may need to receive IV Vancomycin for several weeks. We can sometimes send them home with a peripherally inserted central catheter, or PICC line. Depending on the medication, they may need a nurse to visit them at home to give the medicine.
6. It’s important to remember that not all medicines that are intravenous come in oral forms, and vice versa. For instance, cefazolin, also known by the brand name Ancef, is only IV, while cephalexin, or Keflex, is only PO. So if you’re doing an outpatient rotation and the attending asks what you want to prescribe for a patient to take at home, and you think that a first-generation cephalosporin would be a good idea, you could suggest cephalexin, but not cefazolin.
7. Oral medicines come in liquid and tablet or capsule form. Some, such as Amoxicillin, also come in chewable tablets. Once children get to be 4 or 5 years old, I always ask the child if they would prefer liquid or pills. You will sometimes be surprised at what they say – I’ve had 4 year olds who can swallow pills, and I’ve had 16 year olds who want liquid medicine.
8. Learning to swallow pills is a big deal that can cause many children anxiety. Most children learn to swallow pills by first trying to swallow small candies or chewable vitamins. I have found that the best way to practice swallowing pills is to buy a pack of Tic Tacs. They have a similar consistency to tablets and don’t melt or dissolve as easily as other candies. Small chewable vitamins also work pretty well, although some children have trouble with the irregular shapes of some of these.
9. When the medication is in liquid form, how it tastes can often be important for adherence. For instance, Amoxicillin tastes like bubble gum, and most children don’t mind the taste. Clindamycin has a bitter taste, so if you’re prescribing this medicine, you need to let the parent and/or child know. You can make suggestions of favorite foods they can put it in, like chocolate sauce or ice cream that may mask the flavor, but it is very important to counsel on this so they are not surprised that it tastes bad.
10. Liquid medications often come in different concentrations. Try to prescribe the most concentrated suspension that is available. For instance, Amoxicillin comes in several concentrations: 125, 250, and 400 mg/5 ml. If a child weighs 20 kg and has to take 50 mg/kg, that is 1000 mg. It is going to be much easier for this child to swallow 12 ml of the 400 mg/5ml suspension than 40 ml of the 125 mg/5 ml suspension. 40 ml is the equivalent of 8 teaspoons! Even though Amoxicillin tastes ok, that is still a lot of medication, and most children will not be able to take that much volume.
11. Always prescribe oral medicine in milliliters instead of spoonfuls. Studies have shown that pediatric patients are more likely to get the correct dose when the medicine is prescribed in milliliters than if it’s prescribed in teaspoons or tablespoons. Patients can definitely use measuring spoons to give medicine. If that is the case, then you’ll want to know that 5 ml = 1 teaspoon, and 15 ml = 1 tablespoon. However, many parents will think that you mean a kitchen spoon. So milliliters is always the most accurate way to prescribe the medicine. The pharmacist can give the parents a syringe or medicine cup with milliliter markings to give the medicine. Some clinics also have them available to give to parents, so check with the nurses to see if you can give them one.
12. Some oral medications are not easily available in liquid form. For instance, although there is a liquid form of methylphenidate to treat children with attention deficit-hyperactivity disorder (ADHD), some insurance companies will not pay for it. One option would be to find a compounding pharmacy that will make the liquid formulation. However, that may not be available in your community, and you may have to choose another medication altogether. The other option is to figure out how to make the tablet or capsule formulation work for the patient. This can be complicated, particularly when the dose that your patient needs is not the dose that is available in pill form. Here are some options:
a. Some tablets are scored with a mark, so that it’s easy to fairly accurately cut the tablets to get smaller doses that are fairly equal.
b. Most tablets can also be crushed and mixed in with food, such as applesauce or pudding, to give to the child. Some parents will mix the medicine with some juice or milk. That is fine, but I usually recommend mixing it with just a small amount of the juice or milk – in general, no more than 1 oz, because the child needs to drink the whole amount to get the correct dose of the medicine.
c. With capsules, you have to be careful. In general, if the capsule contains powder, you can open up the capsule and mix the powder in with food. There are some medicines for which you cannot do it. This is particularly true for time-release formulations, such as with some of the ADHD medicines. Patients have to swallow these capsules whole.
13. If there is an option about the frequency of giving the medicine, in general use the least frequent option. In the hospital, for instance, if you prescribe ceftriaxone IV, which can be given once a day (QD) or twice a day (BID), the nursing staff will be much happier with you if you prescribe it every 24 hours instead of every 12 hours. Also, there may be times when you have the choice of two medications that are clinically similar, and the one that has to be given less frequently may be a good option. When the medicine is to be given at home, fewer doses are also in general easier for the family, and they’re more likely to give the child all of the medicine. For instance, for a child with strep throat, you can give amoxicillin 50 mg/kg/day once a day (QD), twice a day (BID), or 3 times a day (TID). It’s the same total daily dose. I usually try to prescribe it once a day. However, having said that, some children have difficulty with large volumes of medicine. So the family may prefer to have the medicine dose split up during the day. You do want to stay within the prescribing guidelines, though. For instance, you can’t have them divide it into 12 hourly doses, because if you remember from that pharmacokinetics lecture, you need a certain amount to reach therapeutic concentrations. Also, even though it seems like an obvious thing, I often suggest that the family sets alarms on their phone so that they remember to give the child the medicine. Every family has a lot to keep track of, and it is easy to forget. For most medicines, it’s also okay for the timing to not be exact, so for instance, if a child has to take a medicine 3 times a day, I will ask what time they wake up, come home from school, and go to bed. If the timing is approximate, I can then suggest, “Give it to her at breakfast time, when she comes home from school, and at bedtime.”
Finally, I want to end by talking about two commonly used over the counter medications: acetaminophen or paracetamol, often referred to as Tylenol, the brand name and Ibuprofen, also known as Motrin or Advil. We generally do not recommend Ibuprofen to infants younger than 6 months old, because it is excreted in the kidneys, and there is concern that the kidneys are not mature enough to handle ibuprofen until the infant is 6 months old. Of note, ibuprofen is not FDA approved for infants younger than 6 months. Acetaminophen can be used in infants as young as 2 months of age. Parents will often have acetaminophen or ibuprofen at home so it is important to guide them how to use it. Both acetaminophen and ibuprofen are available in liquid and tablet forms, and acetaminophen is also available in rectal suppository form. The standard concentration for acetaminophen is 160 mg/5ml and the standard concentration for ibuprofen is 100mg/5ml. The bottle label may say “children’s Tylenol” or “infant Tylenol,” but the concentration is the same. The dosing charts on the back of the bottle are weight based, but they also say that parents should ask a doctor before giving the medicine to children under 24 lbs and 2 years of age. This is not because the medicine is unsafe but because younger children with fever are more likely than older children with fever to need to be evaluated. So parents will call in the middle of the night for this. At well child checks or sick visits, it is a good idea to give parents a weight-based chart for dosing of these common medications that includes lower weights, so that they have this at their disposal. Acetaminophen can be dosed every 4 hours and Ibuprofen is dosed every 6-8 hours. You will hear parents or healthcare providers talk about alternating medications. That means that a parent is giving one medication, say Tylenol and then in 3 hours give Ibuprofen and then in 3 hours give Tylenol again, so each medication is being given every 6 hours. Be careful with this recommendation as it can be very confusing to keep track of what has just been given, and it is easy to give too much of either medicine. There is also not good evidence that alternating acetaminophen and ibuprofen is better at fever control.
Today, we discussed a lot about prescribing medications in pediatrics! It can be a little overwhelming at first when you’re trying to figure out which medication to use and calculating drug doses. But you will get the hang of it after you’ve done it a few times.
OUTRO:
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