Dosage and Solutions PDF

# Dosage and Solutions ## Definition of Terms - **Dosage:** Accurate and proper way of giving medicines in prescribed doses. - **Dose:** Exact amount of medicine to be given or taken by the patient at one time or at stated intervals. ## Administration of Drugs - **Oral Administration:** - **Pare...

# Dosage and Solutions ## Definition of Terms - **Dosage:** Accurate and proper way of giving medicines in prescribed doses. - **Dose:** Exact amount of medicine to be given or taken by the patient at one time or at stated intervals. ## Administration of Drugs - **Oral Administration:** - **Parenteral Administration:** - Intramuscular - Intravenous - Subcutaneous ## Common Abbreviations ### By Route - IM, IV, SC, SL, ID, p.o., p.r. ### Frequency - od, bid, tid, qid, qh (q4h), ac/pc, prn, qd ## Drug Order The drug order consists of seven parts: - Name of the patient - Name of the drug - Dosage strength and form of the drug - Route by which the drug is to be administered - Frequency, time and special instructions related to administration - Date and time when the order was written - Signature of the person writing the order **Example:** Naproxen 250mg/tab 1 tab p.o. b.i.d. ## Parenteral Administration The maximum dosage volume to be administered per IM injection site for an average 150 lb adult is 3mL, for children ages 6-12 years is 2mL, and children from birth to age 5 years is 1mL. Parenteral drugs are in the form of ampules or vials. ## Oral and Parenteral Dosage Administration - **To Solve Use:** - Factor-Label Method - Ratio and Proportion - **Formula:** $x = \frac{D (desired dosage)\times Q (quantity)}{S (stock available)}$ ## Exercises 1. **Order:** Furosemide, 160 mg, od **Available:** 40 mg tablets *How many tablets should the patient receive?* D/S = 160mg/40mg = 4 tablets 2. **Order:** Trisilate 1500mg, q12h for 5 days **Available:** Trisilate liquid, 500mg/15mL *a. How many mL should the patient receive?* D/S = 1500mg ÷ 500mg/15mL = 45 mL *b. How many mL is consumed all in all?* 45 mL x (2x a day) x 5 days = 450 mL 3. **Order:** Phenobarbital grss, PO, qid **Available:** Phenobarbital 15 mg tablet *a. How many tablets per dose?* D/S = (1/2gr x 60mg/1gr) ÷ 15 mg = 2 tablets *b. How many tablets per day?* 2 tablets/day x 4 times a day = 8 tablets/day 4. **Order:** Dicloxacillin 100mg, PO, q8h, for 7 days **Available:** Dicloxacillin 62.5mg/5mL *a. How many mL should the client receive?* D/S = 100mg ÷ (62.5mg/5mL) = 8mL *b. How many mL was actually consumed?* 8 mL x 3 times a day x 7 days = 168mL 5. **Order:** Atropine sulfate gr 1/200, SC **Available:** Atropine sulfate 0.4mg/mL *How many mL should the patient receive?* D/S = (1/200gr x 60mg/1gr) ÷ 0.4mg/mL = 0.75 mL 6. **Order:** Aspirin grx, STAT **Available:** Aspirin 325mg tablet *How many tablets should the patient receive?* D/S = (10gr x 60mg/1gr) ÷ 325mg = 2 tablets (1.8) 7. **Order:** Scopolamine 0.3mg, SC **Available:** Scopolamine ampule in gr 1/200 per mL *How many mL should the patient receive?* D/S = 0.3 mg ÷ (1/200 gr/mL x 60mg/1gr) = 1 mL 8. **Order:** Cephalexin 40mg/kg/day, PO, q6h, 33 lb child **Available:** Cephalexin 250mg/5mL *a. How many mg should the child receive per day?* 33 lb = 15kg x 40mg = 600mg/day *b. How many mL per dose?* D/S = 600mg ÷ (250mg/5mL) ÷ 4 = 3mL/dose 9. **Order:** Allopurinol 450mg, PO, qid **Available:** Allopurinol 300mg tablet *How many tablets should the patient receive?* D/S = 450mg ÷ 300mg = 1.5 tablets per dose/ 6 tablets per day 10. **Order:** Sulfisoxazole 50mg/kg/day, PO, q6h, 44 lb child *a. How many mg per day?* 44 lb = 20kg x 50mg/kg/day = 1,000 mg/day *b. How many mg per dose?* 1000mg/day ÷ 4 doses/day = 250mg/dose ## Pediatric Dosages - Based on Age - **Fried's Rule - newborn to 2 y/o** $\frac{Age in months \times Normal adult dose}{150}$ **Example:** The physician prescribed Dolanex elixir for a 15-month-old. The normal adult dose is 325 mg q4h to q6h. Dolanex elixir is available as 325mg/5mL. - **Young's Rule - ages 1 to 12 y/o** $\frac{Age in years \times Normal adult dose}{Age in years + 12}$ **Example:** The physician prescribed Milk of Magnesia for an 8-year-old patient. The normal adult dose is 30mL. ## Pediatric Dosages - Based on Weight - **Clark's Rule - 2 y/o and older children** $\frac{Weight in pounds \times Normal adult dose}{150}$ **Example:** The physician prescribed Dolanex elixir for a 4-year-old who weighs about 30 lbs. The normal adult dose is 325 mg q4h to q6h. Dolanex elixir is available as 325 mg/5mL. ## Insulin Administration **Formula:** $\frac{Desired}{Stock \div 16 minims}$ **Sample Problem:** The patient needs 30U of Insulin but the available stock is 80U. *f. How much of the 80U will be given?* *g. If the stock is 100U, how much should be given to meet the patient's needs?* ## Intravenous Infusion - **Calculating mL/hour** $\frac{Total volume to be infused (mL)}{Total time (hours)}$ **Sample Problem:** A patient is to receive 1 liter of Ringer's solution over a 6-hour period. The patient would receive [insert the calculated value] mL/hour. - **Calculating mL/min:** $\frac{Total volume to be infused (mL)}{Total time (in minutes)}$ **Sample Problem:** A patient is to receive 500mL of NSS over a period of 4 hours. The patient would receive [insert the calculated value] mL/min. - **Calculating gtt/min:** $\frac{Total volume to be infused (mL) \times SDF (15)}{Total time (in minutes)}$ **Sample Problem:** Administer 1 liter of D5W over 8 hours. Calculate the gtt/min. ## Exercises - The physician prescribed 800mL of RL to infuse over 12 hrs. You would give [insert the calculated value] mL/h. - The physician prescribed an IV of 100mL of DW to run at 100mL/h. The drop factor is 10. Set the flow rate at [insert the calculated value] gtt/min. - Order: 1000mL to be infused at 150 mL/h. The drop factor is 20. How many gtt/min is this? - Order: 2000mL to be infused for 12 h. The drop factor is 20. *a. How many mL/h is this?* *b. How many gtt/min is this?* ## Solutions - **Factor-Label Method** - **Ratio and Proportion:** Desired sol'n: Available sol'n:: Amount of solute: Total amount - **Formula Method:** Amount of solute = $\frac{Desired Strength \times Total amount}{On-hand strength}$ - **To Calculate the Quantity of Water or Diluent Used:** Quantity of diluent = quantity (soln) - quantity (solute) ## Sample Problems - To prepare 400mL of a 2% sodium bicarbonate solution from a pure drug, you would need [insert the calculated value] g of solute. - To make 1.5L of a 5% solution from a 25% solution, you would need [insert the calculated value] mL of solute. Add [insert the calculated value] mL of water to make 1.5L. - There is 500mL of 40% magnesium sulfate solution available for a soak. To make 30% solution you would need [insert the calculated value] mL of solute. Add [insert the calculated value] mL of water to make 500mL.