Oral Dosage of Drugs Chapter 10 MAT 119

Medication Administration Medication administration is the way that a drug is introduced into the body. The route of administration is chosen according to the speed of absorption desired and the site of action of the medication. Some medications are formulated for a specific route only and must be given in that manner. It is important that medicines be administered as directed by the manufacturer.

Oral Medication Administration Oral and enteral administration require that the medication not be destroyed by the environment of the stomach and digestive enzymes. It is too slow if rapid absorption is required, and cannot be used if the patient is vomiting. Rectal administration in the form of liquids or suppositories circumvents this problem in enteral administration.

Oral Medications Oral drug forms are generally the easiest for the patient to take and the most convenient for the nurse to administer.

Oral Medications Oral medications come in a variety of forms Tablets Powered drugs compressed or molded into solid shapes. Plain tablets may be crushed for easier swallowing. Scored tablets Have a line down the center so the tablet can be broken into halves Unscored tablets should not be broken because there is no certainty that the drug is evenly distributed.

Pill Cutter & Pill Crusher

Oral Medications Capsules Gelatin containers holding a drug in solid or liquid form. For patients with difficulty swallowing, the nurse can open and put the semisolid in applesauce or custard – should check to see if medication is available as a liquid. Some are enteric-coated or contain particles of the drug that are coated to dissolve at different times. These are long-acting and should NOT be opened (time-release or sustained-release). (Can not crush or open to put in applesauce.)

Oral Medications Coated tablets (film-coated) Enteric-coated tablets Smooth and easy to swallow because of their coating. Some tablets may be crushed. Enteric-coated tablets Dissolve in the more alkaline secretions of the intestine rather than in the highly acidic stomach juices. Reduces the chances of gastric mucosa irritation. Should NOT be crushed!

Oral Medications Prolonged-release or extended-release tablets Disintegrate more slowly and have a longer duration of action. Decreases the number of doses of tablets Should NOT be crushed!

Oral Medications Sublingual tablets Coded tablets Dissolve quickly under the tongue Medication is absorbed through capillaries and reaches the circulation without passing through the GI tract. Coded tablets Have a number or letters, or both, that make them easily identifiable.

Oral Medications Syrups Elixirs Solutions Solutions of sugar in water that disguise the medication’s unpleasant taste – contraindicated in patients with DM Elixirs Clear hydro-alcoholic liquids that are sweetened – contraindicated in patients with a history of alcoholism Solutions Clear liquids that contain a drug dissolved in water.

Oral Medications Powders Dry, finely ground drugs that need to be reconstituted (dissolved) according to manufacturer’s instructions. In liquid form, becomes an oral suspension. Oral antibiotics are often supplied in this form.

Dosage Calculations In dosage calculations, you need 3 pieces of information: The doctor’s or healthcare provider’s order The quantity or strength of drug on hand The solid or liquid form of the supply drug Find a method that works for you Three-step approach (formula method) Ratio/Proportion Expressed as ratios or fractions

Three-Step Approach Estimate before attempting to calculate dosage Memorize approach Use for every dosage calculation

Three-Step Approach D represents desired dosage or doctor’s order H represents the dosage on hand per a quantity Both H and Q represent the supply dosage found on the label of the drug available

Three Steps to Dosage Calculations Formula Method Step 1. Convert Ensure all measurements are in the same system of measurement and the same size unit of measurement. If not, convert before proceeding. Step 2. Think Estimate what is a reasonable amount of the drug to be administered.

Three Steps to Dosage Calculations Formula Method Step 3. Calculate Apply the formula

Ratio: Proportion What you have : What you need Dosage on hand = Dosage desired Amount on hand X amount desired Supply = Dosage Have X amount

Three Step Approach Doctor’s order: Aricept 10 mg po daily Convert No conversion is necessary. Units are in same system (metric) and the same size (mg). Think Wanting to give 10 mg and you have 5 mg in each tablet. You want to give twice the equivalent of each tablet or 2 tablets per dose.

Doctor’s order: Aricept 10 mg po daily Ratio/Proportion: Step 3-Calculate:

Doctor’s order: Verapamil SR 240 mg po daily Convert – none needed Think – What I need is what I have Calculate – no calculation needed

Ordered: Flagyl 0.75 g po tid How many tablets per dose should be administered? Convert Think Calculate

Ordered: Flagyl 0.75 g po tid How many tablets per dose should be administered? Convert: 0.75 g to mg = 750 mg Think: Am I going to give more or less than I have on hand? Calculate:

Oral Liquids Oral liquids are supplied in solution form and contain a specific amount of drug in a given amount of solution. The supply container label indicates the amount of drug per 1 milliliter or per multiple milliliters of solution. 10 mg per 2 mL 125 mg per 5 mL 1.2 g per 30 mL

Doctor’s Order: Ceclor 250 mg po q 8h Convert Think Calculate

Doctor’s Order: Ceclor 250 mg po q 8h Convert: No Conversion necessary Think: I need to give 2 times the amount I have on hand Calculate:

Order: Potassium 40 mEq po daily Convert: No conversion is necessary Think: you want to give more than 20 mEq, actually twice as much. Calculate:

Conversions If the dosage is not in the same size unit of measurement You must convert to the same system or same size units Metric to metric is most often used Usually go to smaller unit Household Measurements Convert to metric equivalents Metric system is predominant system of measurement for drugs

Converting to Same System Math Tip In most cases, it is more practical to convert to smaller unit Usually eliminates decimal or fraction, keeping calculation in whole numbers

Math Tip When solving dosage problems for drugs supplied in tablets or capsules Q (quantity) is always one, because the supply dosage is per one tablet or capsule Q = One tablet or capsule

Remember Do not always rely on a formula. Always estimate what is a reasonable amount of the drug to be administered. This helps to identify if the dosages calculated are reasonable and sound.

Problem The physician ordered Amoxil (amoxicillin) 0.5 g p.o. q 8 h. Available is Amoxil (amoxicillin) oral suspension 250 mg/5mL, total volume of bottle is 180 mL. a. How many mL of Amoxil will you administer? __________ or __________ t b. How many full doses are available? ______ c. If the physician’s order is for 5 days, is this an adequate total volume? __________ 10 mL 2 18

Problem The physician ordered Prozac (fluoxetine hydrochloride) 40 mg p.o. at 0730 and 2200. Available is Prozac oral solution of 20 mg/5mL. a. How many mL of Prozac will you administer? _______________ b. If the bottle contains 120 mL, how many days will this last? _________________ 10 mL 6 days

Problem The order states Zithromax oral suspension 600 mg p.o. 1 hr ac in am. Available is Zithromax 200 mg/5 mL. a. If breakfast is served at 0800, when should the nurse administer the medication? ______ b. How many mL will you administer? ___ ____ or ________ t________ T 0700 15 mL 3 1

Problem The order reads K-Lor (potassium chloride) oral solution 60 mEq in equally divided doses p.o. tid pc (30 min – 1 hr) a. How many mEq should you administer per dose? ___ b. If K-Lor solution is available 20 mEq/15 mL, how many mL will you administer daily? c. What times would you schedule the medication if breakfast is 0800, lunch is 1200, and dinner is 1700? 20 mEq 0830-0900, 1230-1300, 1730-1800