Techniques of calculation and prescribing pediatric drug dosage

Dose of Commonly used drugs (parenteral)DrugsIndication with Dose FrequencyPreparationAminophylline5mg/kg/dose stat2.5mg/kg/dose for maintenance therapy125mg/5mLMeropenemOther than meningitis 20-30 mg/kg/dose8 hourly500 mg/vialMeningitis60mg/kg/dose8 hourlyAzithromycin10mg/kg/dose Once daily for 3 days500mg/vialVancomycin10-15mg/kg/dose8 hourly500mg/vialDopamine5gm/kg/min followed by gradual increase up to 20gm/kg/min200mg/5mL vialDose of Commonly used drugs (parenteral)DrugsIndication with Dose FrequencyPreparationNetilmycin3mg/kg/dose12 hourly50mg/2mLPhenobarbitone20mg/kg/dose as loading dose8 hourly200 mg/mlMaintenance5-20mg/kg/day in divided doseClarithromycin15mg/kg/day in2 divided dose12 hourly500mg/vialPhenytoin20mg/kg/dose as loading dose125 mg/5mlMaintenance5-20mg/kg/day in divided doseRelation of Dosage frequency with weight and ageNeonateChildrenAdultDosage frequency of Gentamycin for an example WeightAgeExample IIIExample IBasic CalculationAs the indication is meningitis the baby will receive Injection Meropenem 60mg/kg/dose 8 hourly.So the dose for this baby is 300mg/kg/doseExample I with meropenemAs Meropenem is to be infused not less than 30 minutes, it should be infused with IV fluid. So for the example case IV fluid of choice either Normal saline or Dextrose in aqua or Dexstrose saline is chosen. A measured volume , suppose 30 ml may be taken as carrier for meropenem infusionExample I with meropenemA vial of Meropenem contains 500mg of active drug in powder format. So it should be reconstituted with distilled water. Here comes the measurement of Dilution. If smaller dose is required the dilution should be with more amount of diluents and vice versa.Example I with meropenemSo if dilution is made with 10 ml of D/W then each ml will contain 50 mg of the drug, similarly if dilution is made with 5 ml of D/W then each ml will 100 mg of meropenem. From this diluted drug the exact dose is taken and poured into measured infusion fluid and to be infused.Example I with meropenemIn our example case I the dose is required 6 ml (if diluted with 10 ml D/W ) or 3 ml (if diluted with 5 ml D/W). Now this 3 or 6 ml is poured in to desired amount of fluid to be infused cat calculated time.Calculation of infusion rateCalculation of infusion rateCalculation of infusion rateSo in case of infusing 30 ml fluid the rate will be as follows (drops/min)Basic CalculationAs the indication is acute watery Diarrhoeathe baby will receive Injection Azithromycin @ 10mg/kg/day.So the dose for this baby is 80mg/kg/doseExample II with Azithromycin As Azithromycin is to be infused over 30 minutes, it should be infused with IV fluid. So for the example case IV fluid of choice either Normal saline (as it is provided with the drug as combipack) or Dextrose in aqua or Dexstrose saline is chosen. A measured volume , suppose 30 ml may be taken as carrier for Azithromycin infusion.Example II with Azithromycin A vial of Azithromycin contains 500mg of active drug in powder format. So it should be reconstituted with distilled water. Here comes the measurement of Dilution. If smaller dose is required the dilution should be with more amount of diluents and vice versa.Example II with Azithromycin So if dilution is made with 10 ml of D/W then each ml will contain 50 mg of the drug, similarly if dilution is made with 5 ml of D/W then each ml will 100 mg of Azithromycin From this diluted drug the exact dose is taken and poured into measured infusion fluid and to be infused.Example II with Azithromycin In our example case II the dose is required 1.6 ml (if diluted with 10 ml D/W ) or 0.8 ml (if diluted with 5 ml D/W). Now this 0.8 or 1.6 ml is poured in to desired amount of fluid to be infused cat calculated time.Example IIIRecommended dose of netilmycin in sepsis is 3mg/kg/dose 12 hourly.The baby requires 4.5mg/dose of Netilmycin only.A vial of Netilmycin contains 50mg/2ml.So the baby requires only 0.18 ml of netilmycinExample IIIHere an insulin syringe of 100 U will be helpful for the required dose.As in 100 unit insulin syringe 1ml=100 unit, 0.18 ml refers to 18 unit.So, the dose becomes 18 unit/dose.Thank you all