Final answer:
The time during which a drug remains effective in the body is known as its duration of action. This period is dictated by the drug's pharmacokinetics, including absorption, distribution, metabolism, excretion, and half-life. Considerations for drug dosage include factors like the patient's individual characteristics and potential side effects.
Step-by-step explanation:
The time during which the drug is present in the blood at great enough levels to produce a response is known as the duration of action. This period relates to the pharmacokinetics of a drug, which includes the drug's absorption, distribution, metabolism, and excretion, factors that influence both the plasma drug concentration-time curve (AUC) and the drug's half-life. For instance, a drug with a short half-life may require frequent administration, while a drug with a long half-life can be given at longer intervals. When considering the dosage of a drug, one must consider certain factors such as therapeutic range, patient's age, weight, liver and kidney function, and potential side effects.
Side effects of drugs can include symptoms like nausea, dizziness, and headaches, among others. These effects can be influenced by the drug's specific characteristics, interactions with other substances, and individual patient factors. The concepts of tolerance, where increasing quantities of a drug are needed to gain the desired effect, and withdrawal, a range of negative symptoms experienced when drug use is discontinued, are also important in the management of drug dosages and understanding patient responses.