1.11: Examining Effect
Onset, Peak, and Duration
Dosing considerations play an important role in understanding the effect that a medication may have on a patient. During administration, the nurse must pay close attention to the desired effect and therapeutic patient response, as well as the safe dose range for any medication. The nurse should have an understanding of medication efficacy in order to ensure its appropriateness. If a nurse is provided different medication choices according to a provider’s written protocol, the nurse should select the option with the anticipated desired therapeutic response. Additionally, the nurse must be aware of the overall dose-response based on the dosage selected.
Three additional principles related to the effect of a medication on a patient are onset, peak, and duration.
Onset: the onset of medication refers to when the medication first begins to take effect
Peak : the peak of medication refers to the maximum concentration of medication in the body, and the patient shows evidence of greatest therapeutic effect
Duration: the duration of medication refers to the length of time the medication produces its desired therapeutic effect
Duration and Dosing
Now let’s consider the implication of duration and dosing. Remember the duration of medication is correlated with the elimination. If a medication has a short half-life (and thus eliminated more quickly from the body), the therapeutic effect is shorter. These medications may require repeated dosing throughout the day in order to achieve steady blood levels of active free drug and a sustained therapeutic effect. Other medications have a longer half-life (and thus longer therapeutic duration) and are only given once or twice per day. For example, oxycodone immediate release is prescribed every 4 to 6 hours for the therapeutic effect of immediate relief of severe pain, whereas oxycodone ER (extended release) is prescribed every 12 hours for the therapeutic effect of sustained relief of severe pain.