Intravenous infusions, Parenteral admixtures, and rate of flow calculations

1. Intravenous infusions, Parenteral admixtures, and rate of flow calculations Dr. Asmaa Abdelaziz Mohamed

2. Intravenous (IV) infusions • Intravenous (IV) infusions are sterile, aqueous preparations administered intravenously in relatively large volumes. • They are used to extend blood volume and /or provide electroyltes, nutrients or medications. • Pharmacists participate in the preparation and administration in hospital as well as home IV infusion therapy • Commercially available infusions are prepared in glass or plastic bottles or collapsible plastic ‘bags’ in volumes of 50 ml (a minibag), 100 ml, 250 ml, 500 ml, and 1000 ml.

3. Intravenous (IV) infusions • Additional components or additives frequently are added to the basic IV solutions. • Administration set used to deliver the fluid from IV bottle or bag to patient’s vein. • The sets may be standard (macrodrip) or pediatric (microdrip).

4. Example: How many grams each of dextrose and sodium chloride are used to prepare a 250 ml bag of D51/2NS for IV infusion? 250 X 0.05 (5% w/v) = 12.5 g dextrose 250 X 0.0045 (0.45% w/v) = 1.125 g sodium chloride N.B. D51/2NS means Dextrose 5% in 0.45% Normal Saline Dextrose 5% in 1/2 isotonic Normal Saline IV push (IVP or sometimes as a bolus dose) The rapid injection of IV medications, as in emergency or critical care situations IV push medications frequently are administered in less than one minute, that depends on precise calculations of dose and rate of administration.

5. Example: a physician orders enalaprilat (VASOTEC IV) 2 mg IVP for a hypertensive patient. A pharmacist delivers several 1 ml injections, each containing 1.25 mg of enalaprilat. How many milliliters of the injection should be administered? 1.25 mg 1ml 2 mg X ml X = 1.6 ml

6. Example Calculate the daily infusion volume of D10W to be administered to a neonate weighing 3 lb 8 oz.on the basis of 60 ml/kg/day 3 lb 8oz = 3.5 lb/ 2.2 = 1.59 kg = 1.6 kg 1.6 kg X 60 ml = 96 ml Note : D10W dextrose 10% w/w in water IV oz = ounce= 28.3 g Intravenous Admixtures IV admixtures involves the addition of one or more drugs to large volume sterile fluids.

7. Example A medication order for a patient weighing 154 lb calls for 0.25 mg of amphotericin B (Antifungal) per kg of body weight to be added to 500 ml of 5% dextrose injection. If the amphotericin B is to be obtained from a constituted injection that contains 50mg/10ml, how many milliliters should be added to the dextrose injection? 154/2.2 = 70 kg 70 X 0.25 = 17.5 mg 50 mg 10 ml 17.5 X ml X = 17.5 X10/ 50 = 3.5 ml

8. Rate of flow of intravenous fluid Example: A medication order calls for 1000 ml of D5W to be administered over an 8-hour period. Using IV administration set that delivers 10 drops/ml, how many drops per minute should be delivered to the patient? 1 liter = 1000 ml 8 hours = 480 minutes 1000 ml 480 minutes X ml 1 minute X = 1000/480 = 2.1 ml/ min 2.1 X 10 = 21 drops/ minute

9. Thanks