1. Warm-up: Round to correct sig figs 1.4 x 4 = 2.4.0 x 4.0 = 3.4.00 x 4.00 =

2. Dose Calculations in Medicine In the US about 7,000 death and 1.3 million injuries occur each year due to medication errors.

3. Medical Dose Calculations in the US Some medication doses depend on a patient’s weight – why? A child needs a smaller dose than an adult (overdose!) US patient’s weight in lbs but medication doses are in SI units. Example: 5.25 mg penicillin/kg body weight

4. Converting body weight Need to convert lbs into kg: 1 kg = 2.21 lbs Conversion factor: 1.00 kg 2.21 lbs Example: How many kg does a 150 lb adult weigh? Pathway: Lbs kg 150 lbs x 1.00 kg = 1 2.21 lbs

5. Use Decimal Figures in Medicine Decimal figures of dose recommendations determine the result Use instead of sig figs Example 5.15 mg/kg 2 decimal figures

6. An intramuscular injection is given at a concentration of 0.50 mg/kg of body weight. If a patient weighs 187 lbs, how many mg medication does patient need? Pathway Lbs patient →kg patient → dose 187 lb x 1.00 kg x 0.50 mg = 42.30769mg 1 2.21 lbs 1.00 kg Decimal figures: 2 Round to 42.31 mg

7. A cold medicine for children recommends 0.35 ml per kg body weight. How many ml does a 60 lbs child need? lbs → kg →dose 60 lbs x 1.00 kg x 0.35 ml 2.21 lbs kg 9.5022624 round to 9.50 ml 2 decimal figures

8. Chlorampenical is an antibiotic given at an adult dosage of 1.255 mg per kg body weight. How much antibiotic is needed for a patient with the body weight of 200 lbs? Pathway Lbs patient → kg patient → dose 200 lb x 1.00 kg 0.125 mg = 1 2.21lbs 1.00 kg =11.357466 round to 11.358mg

9. Warm- up A general anesthesia drug requires a dose of 0.15 ml/kg body weight. The anesthesiologist Dr. Sleep administered 6.9 ml to a 105 lb woman for her plastic surgery. The woman did not wake up from the surgery and the anesthesiologist is sued for overdosing the patient. You are the defense lawyer… lbs → kg →dose 105 lbs x 1.00 kg x 0.15 ml = 2.21 lbs 1 kg 7.1266968 round to 7.13 ml 2 decimal figure