Calculations of dosage based on age or weight (see below) are conservative and tend to underestimate the required dose. Doses based on surface area (Table 59–6) are more likely to be adequate.
Age (Young’s rule):
Weight (somewhat more precise is Clark’s rule):
TABLE 59–6 Determination of drug dosage from surface area.1 1For example, if adult dose is 1 mg/kg, dose for 3-month-old infant would be 0.18 mg/kg or 1.1 mg total.
Reproduced, with permission, from Silver HK, Kempe CH, Bruyn HB: Handbook of Pediatrics, 14th ed. Originally published by Lange Medical Publications. © 1983 by the McGraw-Hill Companies, Inc.
Despite these approximations, only by conducting studies in children can safe and effective doses for a given age group and condition be determined.
Briggs GG, Freeman RK, Yaffe SJ: Drugs in Pregnancy and Lactation: A Reference Guide to Fetal and Neonatal Risk, 10th ed. Wolters Kluwer/Lippincott Williams & Wilkins, 2015.
de Wildt SN et al: Ontogeny of midazolam glucuronidation in preterm infants. Eur J Clin Pharmacol 2010;66:165. Gavin PJ, Yogev R: The role of protease inhibitor therapy in children with HIV infection. Paediatr Drugs 2002;4:581.
Hansten PD, Horn JR: Drug Interactions, Analysis and Management. Facts & Comparisons. [Quarterly.]
International Liaison Committee on Resuscitation: The International Liaison Committee on Resuscitation (ILCOR) consensus on science with treatment recommendations for pediatric and neonatal patients: pediatric basic and advanced life support. Pediatrics 2006;117:e955.
Iqbal MM, Sohhan T, Mahmud SZ: The effects of lithium, valproic acid, and carbamazepine during pregnancy and lactation. J Toxicol Clin Toxicol 2001;39:381.
Ito S: Drug therapy for breast feeding women. N Engl J Med 2000;343:118.
Kearns GL et al: Developmental pharmacology—drug disposition, action and therapy in infants and children. N Engl J Med 2003;349:1157.
Koren G, Nordeng H: Antidepressant use during pregnancy: The benefit-risk ratio. Am J Obstet Gynecol 2012;207:157.
Koren G, Pastuszak A: Prevention of unnecessary pregnancy terminations by counseling women on drug, chemical, and radiation exposure during the first trimester. Teratology 1990;41:657.
Koren G, Pastuszak A, Ito E: Drugs in pregnancy. N Engl J Med 1998; 338:1128.
Koren G et al: Sex differences in the pharmacokinetics and bioequivalence of the delayed-release combination of doxylamine succinate-pyridoxine hydrochloride: Implications for pharmacotherapy in pregnancy. J Clin Pharmacol 2013;53:1268.
Madadi P et al: Pharmacogenetics of neonatal opioid toxicity following maternal use of codeine during breastfeeding: A case control study. Clin Pharmacol Ther 2009;85:31.
Namouz-Haddad S, Koren G: Fetal pharmacotherapy 2: Fetal arrhythmia. J Obstet Gynaecol Can 2013;35:1023.