PM Pediatrics
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Dr. Christina Johns
Senior Medical Advisor, PM Pediatrics

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Anatomy of a Prescription

I’ve written a lot of prescriptions in my day. Since I strive to be at #nerdalert level: expert I tried to come up with an estimate of how many I’ve written in 20 years, and my low ballpark number is over 9,250. And those are outpatient Rx’s only and do not include the inpatient med orders I wrote while I was in training. Lots of medicine dealt out by me.

I’ll never forget the day in medical school when we learned about how to write a prescription properly: I think I practiced my official “signature” about thirty thousand times. I wanted the C and the J to blend together in a super arty way. Of course this was all back in the day before faxing or e-prescribing even existed. We wrote our prescriptions on paper, and I wanted mine to look all professional and good. As medical students we took our time to be sure that every element was included perfectly, latin abbreviations and all, and in doing so most young physicians developed their own individual system of ordering their Rx.

I think it might be interesting and even helpful for you to know what should go into a medication prescription, and so I’ll go through my process here.

First, before writing anything, the type of paper is important.

Written prescriptions are now mandated to be on tamper-resistant paper. This is that thick stock paper that is grey-blue and almost looks like the same paper from your checkbook. This is most important for prescriptions for controlled substances as opposed to medicines like antibiotics, but in the current environment, all written prescriptions should be on tamper resistant paper printed with the provider’s name, phone number, NPI (National Provider Index) number, and sometimes DEA (Drug Enforcement Agency) and CDS (Controlled Dangerous Substances) numbers. Some providers leave the DEA/CDS numbers off the pre-printed prescriptions because impostors have tried to “steal” the numbers to try and obtain opioids and other pain killers and controlled substances. Sadly, it’s happened to me, and fortunately a smart pharmacist called me when something seemed “off” and we were able to report the violation. This situation doesn’t happen often in pediatrics, thankfully, and as electronic prescribing has become more of the norm, patients have less access to these key IDs and therefore less opportunity for them to wind up in the wrong hands. When I write a paper prescription I always hand write my DEA so that it appears in as few places as necessary.

Next, the name of the medicine seems like it would be straightforward, but there are some key details.

In general, we try to write for the generic medicine preparation because it’s the same thing as the brand name, but usually less expensive. In addition, since many drug manufacturers can make a particular medicine, writing for the generic allows for more seamless filling of the Rx since there’s no way every prescriber can know which pharmacy has a contract with which manufacturer. If the prescription is for the generic form, the pharmacy can complete the order using what they have. These medicines are regulated by the FDA, so the quality of the medicine shouldn’t be any different from one US manufacturer to another.

The strength of the medicine needs to be written next to the name:

do I want to give someone 400mg or 875mg of Amoxicillin? I need to be very clear on that. This is especially important in pediatrics because (as I’ve written before) nearly all medicines are dosed on a milligrams of medicine per kilograms of weight basis. Some medicines are available in just one concentration, but most have a few options so specifying which strength is desired is as important as the name.

Now we need to indicate HOW to take the medicine.

This is usually written as

Sig: … and then the directions. One tab, or 10ml, or 2 caps, etc.

Sig is an abbreviation for the latin signetur which means “let it be labeled.” There’s more Latin in this section too. If a medicine is to be swallowed, we write PO or “per os” or “per orum.” We indicate under the tongue by “SL” or sublingual, and OU (oculus uterque), OD (oculus dextrus) and OS (oculus sinister) for both eyes, right eye, and left eye respectively.  So now we know what kind, what strength, how much and where to put the medicine, but we need to know how often. Did you take Latin in high school? I wish I did. Here’s how we indicate how often a medicine should be taken.

QD: (quaque die) once a day

QOD: (quaque altera die) every other day

BID: (bis in die) twice a day

TID: (ter in die) three times a day

QID: (quater in die )four times a day

QHS: (quaque hora somni) at bedtime

QAC: (quaque ante cibum) with meals

Sometimes medicines are given on an “as needed” basis— and that is indicated by the abbreviation “PRN” for “pro re nata.” A reason has to be given for when to use the as needed medicine: “prn itching” or “prn fever.”

Ok. So now the prescriber has been clear about exactly how to take the medicine. But how much medicine should we get?

That’s where we write:

Disp: which stands for “dispense.” We then write how much we want to give, like 20 tablets, or 150ml. Some prescribers write the “#” and then the number written in text. For example, #twenty. If the type of medicine is written above, like “tabs” or “caps” in the directions, then it doesn’t need to be repeated in the dispense line, but I always do just for extra clarity.

Usually there’s an area to indicate if any refills should be automatically authorized. This is done for chronic daily medicines but not for acute courses of medication, like antibiotics.

It goes without saying that the patient’s name and date of birth should go on the prescription as well; these are basic identifiers. In pediatrics we tend to add the weight (kg) so the pharmacist can double check the dosing calculation.

Alrighty, I think we’re done. That’s a lot, no? All those details stuffed into half a sheet of paper or a small pop up square on a screen. Worth it to know the elements.

One More Thing!

Last but certainly not least the Rx needs to be signed and dated. Of course all the new electronic prescribing systems allow a prescriber to sign prescriptions electronically, but I still like the old school paper documents when I get to practice my pen and ink signature. And it is just one tiny step above the typical doctor-grade scribble, don’t you think?

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