Final answer:
Drug concentration typically decreases over time due to metabolism and excretion. Dosage is influenced by half-life and whether the drug's action is dose or time-dependent. Proper dosage and awareness of side effects are crucial for safe and effective drug administration.
Step-by-step explanation:
The concentration of a drug in a patient's plasma after administration typically decreases over time. This decrease is due to the drug being metabolized and excreted from the body. Factors such as the drug's half-life, whether it is dose-dependent or time-dependent, and administration route (intravenous, oral, or intramuscular) influence the rate and pattern of concentration change. In pharmacokinetics, the half-life of a drug is particularly crucial, as it determines the dosage and frequency required to maintain effective therapeutic levels. A drug with a short half-life will require more frequent dosing than one with a long half-life. Additionally, drug concentration can impact side effects; drugs with longer half-lives may maintain higher toxic levels for extended periods, thus careful dosage considerations are needed to minimize risks.
When determining the dosage of a drug, one must consider the drug's half-life, the administration route, whether the drug is dose-dependent or time-dependent, potential side effects, and patient-specific variables such as age or comorbid conditions. Side effects associated with drugs can vary widely but often include symptoms such as nausea, headache, dizziness, and allergic reactions. Factors contributing to side effects can be the drug's dosage, duration of treatment, interactions with other medications, and individual patient characteristics.