DRUG CALCULATION WORKBOOK
CONVERSION GUIDE
Follow these guidelines to convert metric weight: 1. Each step equals 3 decimal places 2. Remember the acronym DR UL. This stands for Down Right Up Left. _______Kg______ l l l_____g_____ Kilogram gram
l l l___mg____ milligram l l l___mcg___ microgram l l To change a mg to a gram, move the decimal to the left three places. Take the mg and since you have to move Up the stair, move Left with the decimal. (DR UL) 2.5 mg = 0.0025 g To change a kilogram to a gram, move the decimal to the right three places. Move Down the stairs and take the decimal to the Right. 1.2 Kg = 1200 g In the same way, change a gram to a microgram. This requires a decimal move six places. 0.22 grams = 220,000 mcg
KNOW THE FORMULA Drug Calculations are easy once you remember the formula. To set up the formula, make a cross and fill in the appropriate numbers. The on hand goes on the upper left. How supplied is lower left. Because the Dr. is “always right” put the Dr.’s order on the upper right and the answer will be on the lower right.
ON HAND 250 mg HOW SUPPLIED 1 ml
DOCTOR’S ORDER 50 mg FINAL RESULT ? ml
The term of measurement must be the same in both top boxes. Then, the how supplied and final result will also be in the same term of measurement. Notice the on hand and Dr.’s order is both in mg. If one measurement is mg and the other mcg, a conversion would be necessary to change to the amount on hand. The math involves multiplying the how supplied by the Dr.’s order. The result of that equation lives in the division house and gets divided by the on hand. See below: ON HAND DOCTOR’S ORDER 250 mg
DIVIDE
50 mg
HOW SUPPLIED FINAL RESULT
1 ml
MULTIPLY
? ml
50 X 1 = 50 Divided by 250 = 0.2 Therefore, 0.2 ml is the amount to administer.
Points to Remember: 1. Both ml and cc are the same amount. 1 ml = 1 cc 2. All medications begin in a powder form 3. Use the step conversion and formula for accurate drug administration 4. Carefully read labels 3 times when administering medication. 5. Remember you 7 rights. a. Right patient b. Right Drug c. Right dose d. Right time e. Right route f. Right technique g. Right documentation __________________________________________________________________ Drug Forms Liquids – are drugs that have been dissolved or suspended to rapidly absorbed in the stomach Solution – one or more drugs dissolved in a solvent such as saline. Syrup – a solution of sugar and water, with medication and flavor added. Expectorant – contains drugs that aid in coughing up secretions of Respiratory Tract Suspension – contains a finely divided solid distributed throughout a liquid. Has a tendency to “settle out”, must be shaken before use. Elixir – a sweetened liquid containing oral medication. Tincture – medication that is dissolved in a alcohol solution. Emulsion – a mixture of two liquids that normally do no combine. Solids and Semi-solids – allows flexibility in dosage Liniment – medication mixed with soap, oils, alcohol or water. Designed to produce heat and used for external use only. Lotion, Cream, Ointment – soft, semi-solid preparations, usually containing medications for application to the skin or mucous membranes. Capsule – a solid dosage from which the drug is enclosed in a shell of hard or soft gelatin. To be used for oral use only. Tablet – a powder compressed into a disk or oval shape, may have enteric coating. Caplet – shaped like a capsule, but has consistency of a tablet. Lozenge – round disk in sweetened base, sometimes contains medication Suppository – drug combines with oil, glycerin, or cocoa butter. Cylinder shaped. Not for oral use. To be inserted into rectum or vagina. Miscellaneous Inhalants – contain aerosols that are used as propellants for medications. Sprays – administered through an atomizer. (Nasal sprays) Topicals – absorbed through the skin Instillation – adhesive patches impregnated with medication that is absorbed through the skin. Implantable – devices containing medications that are embedded beneath skin or into a body cavity.
PEDIATRIC DRUG CALCULATIONS: Pediatric drug calculations require a couple extra steps in the formula. The PDR lists the manufacturer’s recommendation for use based on weight. Therefore, the weight of the child needs to be calculated in metric terms. One Kg = 2.2 lbs Child weighs 30 lbs. Divide this weight by 2.2 to get the weight in Kg. 30 2.2 = 13.6 30 lbs = 13.6 Kg The manufacturer recommendation for Naprosyn used for juvenile arthritis is: 5 mg/kg/day To use this equation find the kg weight of the patient and plug it in as follows: 5mg/13.6kg/day Read this five milligrams times 13.6 kg per day. 5 x 13.5 = 68 mg per day Naproxen, another form of Naprosyn, has recommendation from the manufacturer that states: 10mg/kg in 2 divided doses. If the same 30 lb pt. takes this medication, work the equation as follows: 10mg times13.6kg = 136 mg divided by 2 = 68 mg is given 2 times a day This gives the Dr.’s order portion of the formula. Therefore, the manufacturer’s recommended dose + weight of child in kg (kilograms) is needed in order for the child’s dose of medication to be determined. Once the dose is calculated, plug it in to the drug calculation formula along with the amount on hand. ON HAND DOCTOR’S ORDER 250 mg
NAPROSYN
NAPROSYN
68 mg
HOW SUPPLIED
FINAL RESULT ? ml
2 ml
Do the math. 2 x 68 = 136; 136 250 = 0.5. The amount to administer is 0.5 ml per dose. This dose is given 2 times a day per above recommendations. How supplied is how many tablets, ml, tsp or whatever does it take to weigh the mg on hand. In this case it takes 2 ml to make 250 mg.
Practice: Read each scenario carefully and do the math. 1. An adult patient came into the office with NVD and the Dr. ordered 60 mg of Phenergan IM. The vial on hand reads 100mg/2ml. How many ml would you give? 2. A patient with acute allergy symptoms came in and the Dr. ordered an injection of Benadryl 30 mg. The vial reads Benadryl 60 mg/ml. How many ml would you give? 3. A patient came in for anemia and has a standing order for Imferon 165mg q monthly. The injection is administered deep IM and therefore needs to be given in the Z track route. The vial reads 300mg/3ml for Imferon. What size needle would you need and how many ml would you administer? 4. The Dr. sees a male patient and determines they are hormone deficient. He orders an injection of Depo-Testosterone 65mg. The vial reveals a thick oil-based medication that has 75mg/2ml. What needle would you use and how many ml would you administer? 5. A female patient comes in for her standing order of Depo-Progesterone birth control injection. She is to receive 150 mg IM. The vial reads 90mg/3ml. How many ml would this patient receive? Can this be given in one injection? 6. Another female comes in for her monthly B-12 and Depo-Estradiol injection. These medications can be mixed into one syringe and given IM. The order is B12 (also known as cyanocobalamin) 1500mcg and Depo-Estradiol 70 mg. The vial on hand for cyanocobalamin comes in 1 mg (not mcg)/2ml. The DepoEstradiol vial reads 125 mg/2 ml. How many ml of B-12 and how many ml of Depo-Estradiol would you administer? 7. A 14 year-old patient comes in and the Dr. gives the dx of acute Hepatitis and orders gamma globulin 400 mg IM. The vial reads 750mg/2ml. How many ml would this patient receive? 8. A male patient comes in with the dx of bacterial bronchitis and the Dr. orders an injection of Penicillin 2 grams. The medication comes in pre-filled cartridges of 2,500 mg in the 2ml cartridge. How much of the cartridge would the patient receive? 9. A 3 year old patient that weighs 35 lbs. comes in with pneumonia and has an order for Ampicillin 2.5 mg/Kg every three days. How would you determine what the Dr. order is? The vial reads 300 mg/2ml. How ml will this young patient receive? 10. A 2 year old patient comes in and is ordered an injection of Trimox. She weighs 26 lbs. Trimox is to be administered to pediatric patients with the dose of 2 mg/ Kg/dose. How many ml will she receive if the vial reads 250mg/ml?