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Tablets, capsules, and liquids are the three types of oral medications. They are taken po, or by mouth. Where are oral medications absorbed in the body? Oral medications are absorbed primarily in the small intestine.
Why is it necessary to convert oral drug measurements from one system to another? Physicians can order a drug in one system of measurement when it is supplied in another. It is then necessary to convert between measures so that both measurements are in the same system. Convert the measurements in the example. Because the drug is supplied in milligrams, convert the measurement in the order to milligrams. 1000 mg : 1 g :: x mg : 0.5 g 1 x = 1000 × 0.5 x = 500 mg
What is a capsule? A capsule is a hard or soft gelatin that houses a powder, liquid, or granular form of a specific drug. What is the most common form of oral medication? The most common form of oral medication is a tablet. Tablets are produced from a drug powder.
How many tablets will the nurse administer? Because the order and the available drug are already listed in the same metric measurement, a proportion can be written to calculate the amount of the drug to be administered. 50 mg : 1 capsule :: 200 mg : x capsules 50 : 1 :: 200 : x 50 x = 200 x = 200 ÷ 50 x = 4 The nurse will administer 4 capsules.
Liquid medications come in what two forms? The liquid forms of medications are elixirs and oral suspensions. How is liquid oral medication administered? Liquid oral medication is administered with a medicine cup, plastic oral syringe, or medicine dropper.
How many milliliters will the nurse administer? Because the order and available drug are in the same metric measurement, the proportion can be written. 150 mg : 1 mL :: 750 mg : x mL 150 : 1 :: 750 : x 150 x = 750 x = 750 ÷ 150 x = 5 The nurse will administer 5 mL of atovaquone.
A milliequivalent is the number of grams of a solute contained in 1 mL of a normal solution. How many milliliters will the nurse administer? 10 mEq : 5 mL :: 20 mEq : x mL 10 : 5 :: 20 : x 10 x = 100 x = 100 ÷ 10 x = 10 The nurse will administer 10 mL of Slow-K.
How many tablets will the nurse administer? The desired amount is 5 gr. The available strength is 2 gr. There is no need to convert. [(5 gr)/(2 gr)] × (1 tablet) = x tablets x = 5/2 x = 2 ½ The nurse will administer 2 1/2 tablets.
Convert the order to milligrams per milliliter. 60 mg : 1 gr :: x mg : 2 gr x = 120 mg Place the numbers into the formula ( D / A ) × Q = x. [(120 mg)/(10 mg)] × (5 mL) = x x = 120/2 = 60 The nurse will administer 60 mL.
A physician ordered amoxicillin 0.5 g po four times a day. The drug is supplied in 500-mg capsules.
6.
Calculating Math
Dimensional Analysis
caps = 1 500mg 1g
0.5g 1000mg
500 1 caps
500
7.
Calculating Math
Proportion
0.5g : x :: 500mg : 1 (Change either mg or g)
500mg : x :: 500mg : 1
X= 1 caps
8.
Calculating Math
Formula
D Q x (Dose to be administered)
A
0.5g 1 500mg 1 1 caps
500mg 500mg
9.
Using Proportions to Solve Tablet and Capsule Medication Problems FIGURE 13-1 Forms of solid oral medication. ( Top row: Uniquely shaped tablet, capsule, scored tablet. Bottom row: Gelatin-coated liquid, extended-release capsule, and enteric-coated tablet. (From Potter PA, Perry AG: Fundamentals of nursing , ed 7, St Louis, 2009, Mosby.)
10.
Using Proportions to Solve Tablet and Capsule Medication Problems (cont’d)
Example:
The physician orders minocycline 200 mg po daily. Minocycline 50 mg is available. How many capsules will the nurse administer?
11.
Using Proportions to Solve Liquid Medication Problems FIGURE 13-6 Plastic oral syringe. ( From Clayton BD, Stock YN, Cooper S: Basic pharmacology for nurses, ed 15, St Louis, 2010. Courtesy Chuck Dresner.)
12.
Using Proportions to Solve Liquid Medication Problems (cont’d)
Example:
The physician ordered atovaquone 750 mg twice daily pc. Atovaquone is available 150 mg/mL. How many milliliters will the nurse administer?
13.
Using Proportions to Solve Problems Involving Milliequivalents
Example:
The physician ordered Slow-K 20 mEq four times a day with meals. The drug is available 10 mEq/5 mL. How many milliliters will the nurse administer?
14.
Alternative Formula Method: Capsules and Tablets
Oral dosages involving capsules and tablets
Example:
The physician orders aspirin gr v po four times a day. Aspirin tablets gr ii are available. How many tablets will the nurse administer?
15.
Alternative Formula Method: Liquids
Oral dosages involving liquids
Example:
The physician orders phenobarbital gr ii po twice a day. Phenobarbital elixir 10 mg/5 mL is available. How many milliliters will the nurse administer?