List subscribers, I apologize for the length of this post, but Remek has asked, and I wish to deliver. Others may find it interesting, too.
Dr. Kocz, for the first time in my 33-year pharmacy career, I have a chance of nibbing this one in the bud--you go right ahead and prescribe in milliliters! All pharmacists will understand you exactly. Nothing is stopping you from doing so, and this pharmacist/metricationist would be the most pleased in the world. And, in the U.S., the apothecary system was officially decommissioned by the United States Pharmacopoiea in 1995. That doesn't mean most prescribers haven't ignored or not heard that fact and continued to write their fluid ounces, but certainly there is no rule against ordering oral liquid medication in milliliters and writing directions in milliliter doses. In fact, by writing the dose in milliliters, and also, please if possible, its equivalent in milligrams, you are ensuring that the patient will get the correct dose. A 120 mL portion often gets poured from a larger stock bottle, but that volume is no rule; it is only habit. If you want, order 150 mL; order 200 mL. We measure it and pour it into a dispensing bottle. It all depends upon how much medication you want the patient to have. You are constrained only by the limits of the law, e.g., usually only a 30-days' supply for a so-called "controlled substance" medication (narcotic or similar) Let's say the directions are for the patient to take 5 mL by mouth four times a day (or, every six hours). So, your "standard" 120 mL order turns into a six-day supply of medication. If a five-day supply is what you prefer, you could go an even 100 mL. You are the prescriber; it is your decision. We measure the out and dispense the volume you order. The dispensing bottles (at least in the U.S.) are even calibrated in both fluid ounces and milliliters, and, I would think that, in other countries, they have a milliliter scale only. If they don't have any scales, we use a conical graduate (a graduated glass pharmaceutical beaker) to measure the liquid accurately. Now, granted, some oral liquids are marketed in those pesky 120 mL stock bottles. Well, we are going to end up with a partial bottle if you order only 100 mL, but that's our problem, and if we have to,we might call you to ask to adjust the quantity if it's that urgent. Here's a typical situation: Tussionex, a potent narcotic antitussive (cough) syrup (if you've ever had bronchitis, you've looked forward to benefitting from the quieting effects of this drug product)--is dosed 5 mL by mouth twice a day. That's 10 mL per day. Your patient might need a 10-day supply, so there is your 100 mL prescription order. We pour it out of a 473 mL stock bottle. Why stock bottles of controlled substances are not marketed in round metric sizes is still beyond me. It just makes it that much harder for everyone to inventory--manufacturers, wholesalers, and dispensing pharmacists, and inventory these products we must--as often as every week, depending upon pharmacy policy. U.S. Federal law requires a physical inventory of the stock of all controlled substances in a given pharmacy every two years. On the public side, the problem is that, once you write "5 mL p.o. tid" (meaning, take 5 mL by mouth 3 times a day), you are running up against a public, at least here in the U.S.. which, I believe, doesn't know what you are talking about yet when you say "5 mL." It isn't part of the language yet; the teaspoonful is, still. The U.S. has not yet laid down in its healthcare culture a milliliter-only medicine spoon. Oh, yes, we have plastic spoons available at pharmacies from time to time, but there has not yet been established the routine practice of supplying one with the dispensing of each prescription oral liquid medication. I hope to see the day that safety will mandate both metric-only prescribing and metric-only measuring for oral liquid medications. Incidentally, the Institute for Safe Medication Practices (ISMP), an important U.S. authority on the safe use of medication, recommends that only the metric system be used in prescribing. I could have recommended that myself when I first confronted the issue as a pharmacy student in 1974. Thanks for your patience in reading this lengthy post. Paul ----- Original Message ----- From: Remek Kocz To: U.S. Metric Association Cc: U.S. Metric Association Sent: 21 February, 2009 18:59 Subject: [USMA:43175] Medication sizes. This question goes out mainly to our very own Paul Trusten, but anyone can join in. I'm at the stage of my medical education where we've been taught to write prescriptions, and I see that dosages are typically metric, with an occasional teaspoon thrown in by one of the old-school doctors. However, many liquid med bottle sizes are given in fl oz. On a number of occasions I've been directed to write "Disp 4 fl. oz." on the second line of the prescription many times. The question naturally is, what's the real dispensed size of the bottle? In the future, when I'll do this on my own, can I just put down "Disp 120 mL"? Remek Paul Trusten, R.Ph. Public Relations Director U.S. Metric Association, Inc. www.metric.org 3609 Caldera Blvd. Apt. 122 Midland TX 79707-2872 US +1(432)528-7724 [email protected]
