Final answer:
Selective serotonin reuptake inhibitors (SSRIs) produce antidepressant effects within hours in patients with depression by increasing serotonin levels in the central nervous system.
Step-by-step explanation:
The drug that has been shown to produce antidepressant effects within hours in patients with depression is selective serotonin reuptake inhibitors (SSRIs). SSRIs work by blocking the reuptake of serotonin, thereby increasing the levels of serotonin in the central nervous system. Some commonly prescribed SSRIs include Prozac, Paxil, and Zoloft. It's important to note that the clinical results of these medications may not be seen until weeks later, despite the increase in serotonin release within hours of beginning treatment.