Final answer:
The best treatment for anorgasmia after starting treatment with fluoxetine in a 65 y/o patient with MDD is to consider switching to another SSRI, such as sertraline or bupropion. If this is not effective, other options may include psychotherapy or adding a medication to the current regimen.
Step-by-step explanation:
The best treatment for anorgasmia in a 65 y/o patient with Major Depressive Disorder (MDD) who is experiencing this side effect after starting treatment with fluoxetine is to consider switching to another selective serotonin reuptake inhibitor (SSRI) such as sertraline or bupropion. These medications have a lower incidence of sexual side effects compared to fluoxetine. If switching to another SSRI is not effective, other options may include psychotherapy, such as cognitive-behavioral therapy (CBT), or adding a medication such as bupropion or buspirone to the current fluoxetine regimen.