Final answer:
Drugs not absorbed in the GI tract are typically given by parenteral routes like IV or IM injections, particularly in healthcare settings to ensure higher plasma levels. Dosage is critical to achieve the right therapeutic level and avoid toxicity, with adjustments required for mass in children and for adults with liver or kidney dysfunction.
Step-by-step explanation:
When drugs are not absorbed in the gastrointestinal (GI) tract, they are often administered by a parenteral route, such as an intravenous (IV) or intramuscular (IM) injection. This technique of drug administration is commonly performed in healthcare settings. For many drugs, the plasma levels achieved by intravenous administration are much higher than those achieved by oral or intramuscular routes, which can be particularly important in the treatment of infections.
In terms of dosage and route of administration, it's crucial to determine the amount of medication given during a certain time interval, considering the optimal therapeutic drug levels needed at the infection site while preventing significant toxicity to the patient. For adults and children aged 12 and over, there is usually a standard dose, unlike for children, where the dose is based on the patient's mass. Patients with liver or kidney dysfunction may have reduced drug metabolism or clearance, resulting in higher drug levels and an increased risk of toxicity, necessitating adjustments in dosage.