Clinical Calculation 5 th Edition Chapter 6 Calculation of Oral Medications Pages 40-54 Oral Medications Medications that are administered by mouth and absorbed via the gastrointestinal tract are known as PO (by mouth or orally) drugs. Variation of the oral route is called sublingual (sl) route, whereby medication is placed under the tongue for absorption via the mucous membrane. Buccal route, medication is placed between cheek and gum for similar absorption. Neither sublingual nor buccal medications should be chewed or swallowed whole, as a rule they are not followed by water. Finally it is important to know different forms of oral medication and symbol used and understand how to read labels of medication containers, and calibrating on equipment used to dispense liquid medications. 1
Oral medication forms Tablets Contain a powered drug compressed into a tablet Coated tablets Covered with flavored coating to help swallowing and taste Enteric coated Delay dissolution till it reaches intestine, no dividing or crushed Capsules Gelatin container to conceal taste, ok to open and placed in the food Caplets Looks like capsules it may be coated, but it should not be broken Sustained-release capsules or tablets (time release) Coated to dissolve at different time, should not be broken. Liquids Dispensed as elixirs, syrups, suspensions or solutions Pictures 2
The medicine cup Basically there are 3 different type of measuring cups that we deal with here, and they are collaborated in one or more of the 3 measuring systems Metric system Apothecaries system Household system When solution is poured into a cup page 42 Concave surface is called meniscus and reading should be done at its lowest point. Read the amount in a cup at the eye level and on the flat surface setting. Look and note the smallest collaboration amount in each cup. When measuring smaller amount use syringe for accuracy if not pre-measured. You may use syringe and/or administer with spoon. check and double check before administrating to make sure it is done correctly, it may require to be opened at the bedside for one more opportunity for correct dosage. If between factors use syringe to collaborate the correct amount. It measuring in teaspoon or tablespoon, round to nearest tenth 3
When administrating tablets Tablet is scored in half or quarter Use pill splitter to score un-scored pills If oral medications that are not to be broken/ and it require ½ quantity, consult the pharmacist or the physician in regard to rounding Can be broken Tablets Contain a powered drug compressed into a tablet Capsules Gelatin container to conceal taste, ok to open and placed in the food Can not be broken Enteric coated Delay dissolution till it reaches intestine, no dividing or crushed Caplets Looks like capsules it may be coated, but it should not be broken Sustained-release capsules or tablets (time release) Coated to dissolve at different time, should not be broken. Reading labels and calculating dosage Name of the drug and its generic name Dosage strength: amount or concentration of the drug, per ml, Name of manufacturer Form: liquid-ml, tablet, Expiration date Lot number- manufacturer's code in order to be able to track and trace incase of recall. Total amount per container. Direction for administration (or scoring), mixing, shaking Bar code Recommendation for storage (not on the list) Web site: http://www.accessdata.fda.gov/scripts/cder/drugsatfda/index.cfm?fu seaction=reports.reportsmenu 4
The label for a bottle of medication is shown. 1. Identify the manufacturer's name. 2. Identify the dosage strength of the medication 3. Identify the generic name of the medication. 4. Identify the form of the medication. 5. Identify the trade name of the medication. 1. Pfizer 2. 20 mg 3. piroxicam 4. Capsules 5. Feldene Order: Lasix 20 mg PO How many tablets should be administered? 1. Starting factor = ORDER 2. Answer unit 3. Equivalents equation 4. Conversion equation 5
Order: Aldactone 50 mg PO How many tablets should be administered? 1. Starting factor = ORDER 2. Answer unit 3. Equivalents equation 4. Conversion equation 1. Identify the manufacturer's name. 2. Identify the dosage strength of the medication 3. Identify the generic name of the medication. 4. Identify the form of the medication. 5. Identify the trade name of the medication. 6. Total amount in the container Order: Augmentin 500 mg PO How many ml should be administered? 1. Starting factor = ORDER 2. Answer unit 3. Equivalents equation 4. Conversion equation 6
Order: Calan SR 240 mg PO How many caplets should be administered? 1. Identify the manufacturer's name. 2. Identify the dosage strength of the medication 3. Identify the generic name of the medication. 4. Identify the form of the medication. 5. Identify the trade name of the medication. 6. Total amount in the container 1. Starting factor = ORDER 2. Answer unit 3. Equivalents equation 4. Conversion equation Order: Brethine 5 mg PO How many tablets should be administered? 1. Identify the manufacturer's name. 2. Identify the dosage strength of the medication 3. Identify the generic name of the medication. 4. Identify the form of the medication. 5. Identify the trade name of the medication. 6. Total amount in the container 7
Calculation based on body weight Prescription may prescribed according to a designated amount of drug per kilogram or pound. Because the amount of medication to be given is determined by the weight of the person, the weight and calculated dosage considered an equivalent relationship. Starting factor for this type of the problem is in pound or kilogram. Answer label is in whatever units the medication is dispensed (e.g., ml, mg, tab, etc.). Use dimensional analysis to calculate the correct amount to be administered per dose. Order: Mintezol Suspension 25 mg per kg per dose PO for an adult weighing 60 kg Available Supply: Mintezol Suspension (thiabendazole) 500 mg per 5 ml How many ml should be administered per dose? 1. Starting factor = weight 2. Answer unit 3. Equivalents equation 4. Conversion equation 8
Use dimensional analysis to calculate the correct amount to be administered per dose. Order: Myambutol 15 mg per kg per dose orally for an adult weighing 118 lb Available Supply: Myambutol (ethambutol) 400 mg per tab How many tablets should be administered per dose? 1. Starting factor = weight 2. Answer unit 3. Equivalents equation 4. Conversion equation A client who weighs 62 kg is to receive Nydrazid 5 mg per kg per day PO. The drug label states: Nydrazid (isoniazid) 300 mg per tab. Use dimensional analysis to calculate the correct number of tablets to be administered per dose. 1. Starting factor = weight 2. Answer unit 3. Equivalents equation 4. Conversion equation 9
Use dimensional analysis to calculate the correct amount to be administered per dose. Order: Augmentin 20 mg per kg per day in divided doses PO every 8 hours for a client who weighs 38 kg. Remember to divide by the number of does per day. Use dimensional analysis to calculate the correct amount to be administered per dose. Order: Ancobon 50 mg per kg per day PO in divided doses every 6 hours for a client who weighs 176 lb Available Supply: Ancobon (flucytosine) 500 mg per capsule n g Remember to divide by the number of does per day. 10
Clinical Calculation 5 th Edition Chapter 8 Calculation of Parenteral Medications Pages 83-127 Parenteral Medication Medications that are administered via injection into dermal or intramuscular tissues or directly into vein are called parenteral medications. Administered by route outside the gastrointestinal tract. Parenteral route 1. Intradermal (ID) -Chap 8 2. Subcutaneous (subcut) -Chap 8 3. Intramuscular (IM) -Chap 8 4. Intravenous (IV) -Chap 10 and 11 5. Intrathecal -not covered 6. Intracardial -not covered 7. Intra-articular -not covered 11
The Syringe and Needle Syringe Needle for penetration of the medication and the choice of needle depends on the route and site of administration, the size and obesity of the client, and viscosity of the medication. Hub lower end of the syringe and holds the needle. Barrel holds the medication Plunger made of clouded, color glass or plastic and it is operated to fill or empty the barrel Safety shield to protect its sterility for transport for injection and be locked into place to provide a permanent shield for disposal following injection, some syringes comes with retractable technologies which automatically retracts into the syringe barrel after injection. Needle Hub Barrel Plunger The type of syringes The tuberculin syringes Measures a total of 1 ml, and it is calibrated in hundredths (0.01 ml) and also in minims (16 minims per ml) Used for small quantities of medication and usually used with a 5/8 long needle The insulin Syringes Collaborated in Units and should be used only for administration of insulin. If very small quantity of medication ordered, it is also possible to use Tuberculin syringe, it requires conversion to ml or minims. It is available in 0.3 ml, 0.5 ml and 1 ml. The 0.5, 3, 6, 10, 12, and 35 ml Syringes Smaller ones are calibrated in 0.1 ml and larger ones 10, 12 are calibrated in 0.2 ml 12
The type of Needles The choice of needle depends on the route and site of administration, the size and obesity of the client, and viscosity of the medication. Varies in length from ¼ to 3. Shorter needles (1/4 1 ) are used for intradermal or subcutaneous injections Longer needles (1-2 ) are used for intramuscular injections, irritating medications, and larger or obese clients. Diameter of the needle is indicated by a gauge number. Runs from 14 to 27, the larger the number, the smaller the diameter of the needle Fine needles are used for aqueous solutions and heavier needles for suspensions and oils. Bevel the angle point of the needle increases the sharpness of the needle See page 87 for pictures Reading the Syringe On most single use syringes the plunger has a rubber tip that has 2 rings in contact with the barrel. Measurement must be made at the top ring, the one closer to the tip in order to read the accurate dose. Read at this point and Not here 13
Read the following syringes 1.2 ml 6.4 ml.38 ml Rounding OFF Because clinical calculation does not round to nearest collaborate syringe size, it is necessary to round off these values. When calculating dose obtained does not results in tenths of milliliter, the carry your decimal to hundredths and then For 5 or more round up For less than 5 (4 or less) round down 2.36 = 2.4 2.34 = 2.3 If using tuberculin syringe, it is possible to measure hundredths of ml. Therefore, the computation should be carried to thousandths and then round off to hundredths. 14
Parenteral Medication Forms Drugs for parenteral medication are available in a variety of forms. Some are powder or frozen form and it must be reconstituted to a liquid, where as others are in solution and are dispensed in Single Dose ampoules constricted stem that facilitates snapping them open Single- and Multiple-dose Vials the vial is entered through the rubber diaphragm Pre-filed Cartridges single-dose disposable cartridges, may or may not be a needle attached to the cartridge. Reading Labels Manufacturer s product insert describes, in detail, the composition of the drug, its action, indications and contraindications for use, precautions and adverse reactions, dosage, direction for dilution or reconstitution, and if necessary direction for administration. See sample on pages 93-94 15
Calculating dosages obtained from Premixed Solutions Many parenteral drugs are dispensed in vials or ampoules that contain single or multiple doses. Label or printing on each container indicates the amount and the solution strength of the contents. Use this values as equivalent when calculating quality of solution is needed for the required dosage. Read label 1. Identify the manufacturer's name. 2. Identify the dosage strength of the medication 3. Identify the generic name of the medication. 4. Identify the form of the medication. 5. Identify the trade name of the medication. 6. Total amount in the container 16
Read Label 1. Identify the manufacturer's name. 2. Identify the dosage strength of the medication 3. Identify the generic name of the medication. 4. Identify the form of the medication. 5. Identify the trade name of the medication. 6. Total amount in the container Calculate the correct amount to be administered per dose. Order: diazepam 2.5 mg IM 1. Starting factor = order 2. Answer unit 3. Equivalents equation 4. Conversion equation 17
1. Identify the manufacturer's name. 2. Identify the dosage strength of the medication 3. Identify the generic name of the medication. 4. Identify the form of the medication. 5. Identify the trade name of the medication. 6. Total amount in the container 7. The medication should be stored below what temperature? Calculate the correct amount to be administered per dose. Order: Robinul 0.2 mg IM 1. Starting factor = order 2. Answer unit 3. Equivalents equation 4. Conversion equation 18
A client is to receive chlorpromazine HCl 20 mg IM. The available supply is labeled Thorazine (chlorpromazine HCl) 25 mg per ml. How many milliliters should the nurse withdraw for the IM injection? 1. Starting factor = order 2. Answer unit 3. Equivalents equation 4. Conversion equation Prescription order states: trimethobenzamide 0.2 g IM. The vial of medication is labeled trimethobenzamide 100 mg per ml. How many milliliters should the nurse withdraw for the IM injection? 19
Calculations based on Body Weight Method of calculating based on the body weight is similar to the method used in Parenteral dosages. You have to start from client s body weight. Use dimensional analysis to calculate the correct amount to be administered per dose. Carry the answer to the hundredths place and round to the nearest tenth. Order: isoniazid 5 mg per kg per day IM for an adult weighing 45 kg (maximum 300 mg per day) Available Supply: isoniazid 100 mg per ml 20
Use dimensional analysis to calculate the correct amount to be administered per dose. Carry the answer to the hundredths place and round to the nearest tenth. Order: Amikin 10 mg per kg as a loading dose for an adult weighing 125 lb Available Supply: Amikin (amikacin) 250 mg per ml Reconstitution of Drug in Powder Form Some drugs lose their potency a short time after being placed in solution, so they are not reconstituted until they are ready to be used. A sterile diluents, usually water or 0.9% sodium chloride (normal saltine) must be added according to directions on the label or manufacturer s inserts. Label must indicate for injection or for injection. It is important that only diluents designed in the directions be used for reconstitution, because they have been determined to be compatible with the drug or the IV solutions to which the drug will be added. If asked for water do not added 0.9% sodium chloride. 21
Powder Form After the diluents is added, the vial must be shaken to dissolve the powder, then it may be drawn up into syringe for administration. Diluents volume May expand the volume of the solution. May not expand the volume of the solution. Read the drug label closely to make sure correct strength or concentration of the reconstituted solution to use for correct volume in your calculation. Read label 1. Identify the manufacturer's name. 2. Identify the dosage strength of the medication 3. Identify the generic name of the medication. 4. Identify the form of the medication. 5. Identify the trade name of the medication. 6. Total amount in the container 22
Refer to the information on the medication package provided. In addition to the IM administration route, by which other route can the medication shown be administered? Intravenous Units of Medication Some drugs are measured in quantities called units. It is frequently is used for hormones, vitamins, antibiotics, Because the type of effect varies for each drugs, there is no common definition for a units. 23
Read Label 1. Identify the manufacturer's name. 2. Identify the dosage strength of the medication 3. Identify the generic name of the medication. 4. Identify the form of the medication. 5. Identify the trade name of the medication. 6. Total amount in the container Use dimensional analysis to calculate the correct amount to be administered per dose. Round to the nearest tenth. Calculate the number of ml to be administered for the loading dose. Indicate this amount on the syringe. Order: heparin sodium 3500 units subcut 24
Read label 1. Identify the manufacturer's name. 2. Identify the dosage strength of the medication 3. Identify the generic name of the medication. 4. Identify the form of the medication. 5. Identify the trade name of the medication. 6. Total amount in the container Use dimensional analysis to calculate the correct amount to be administered per dose. Carry the answer to the hundredths place and round to the nearest tenth. Calculate the number of ml to be administered for the loading dose Order: Pfizerpen 3.2 million units in 4 divided doses per day 25
Use dimensional analysis to calculate the correct amount to be administered per dose. Round to the nearest tenth. Calculate the number of ml to be administered for the loading dose. Order: Pfizerpen 400,000 units IM Available Supply: reconstituted supply of Pfizerpen (penicillin G potassium) 500,000 units per ml Clinical Calculation 5 th Edition Chapter 9 Administration of Parenteral Medications Pages 138-142 26
Insulin Preparations Person with diabetes caused by insulin-secretion deficiency may be treated by one or more injection daily of manufactured insulin. Regular insulin is clear solution designated by letter R on the bottle. It is the only type of insulin that can be administered intravenously. Modified insulin designated by L (Lente Insulin), N (NPH insulin) and U (Ultralente insulin). They can only be administered subcutaneously. Lantus is a long acting synthetic human insulin administered subcutaneously. Combination of regular and modified insulin may have been ordered. Such combination may be reported as proportions of regular and modified. Read Label 27
State the dosage strength of the insulin. 100 units per ml Which of the following syringes should be used to administer the order? Answer using the name of the correct syringe. Order: Humulin 50/50 insulin 18 units subcutaneously Unit-100 28