HTHSCI 2H03 Lecture Notes - Lecture 1: Cytochrome P450, Renal Physiology, Bioavailability
18 Nov 2017
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Objective #1: how each of the physiologic developmental changes listed above could affect drug absorption, distribution, metabolism and excretion. The more basic gastric ph of neonates and young children means there are less protons to interact with the administered drugs. Subsequently, the different natures of basic and acidic medications react differently. The less acidic gastric ph makes absorption of weak acids less effective, though the absorption of weak bases improves. Many drugs are still active when secreted from the urine, which means that a more acidic urine would increase reabsorption rates in weakly acidic medicine. Basic medicines due to their nature would be ionized in the acidic environment, and will be excreted faster. Infants have a much higher body water percentage, so highly water-soluble compounds, such as gentamicin, have larger volumes of distribution in neonates compared to adults (hu 2014). Excretion of drugs is reliant on glomerular filtration rate and renal tubular secretion at the site of the kidney.
