Question. I would like information about food/drink and medications. How significant is the impact on absorption availability? And, what is it about Serzone after SSRI? I have not usually seen that much difficulty switching patients from one medication to another but this one seems quite different.
Answer. Foods seem to be a relatively minor factor in the effect or efficacy of psychotropic medications. A few drugs, such as ketoprofen (Orudis) and theophylline, may show altered absorption as a result of food or diet (see Kann et al, Ann Allergy Oct 1989; Le Liboux et al, Eur J Clin Pharmacol 1994; 47:361-6).
Brussel sprouts or cabbage may alter glucuronidation of some drugs (Pantuck et al, Clin Pharmacol Ther 35:161-9,1984). Charles Nemeroff has noted that sertraline taken with food results in higher plasma levels than when taken without food; whereas taking nefazodone with food leads to lower plasma levels (American Society of Clinical Psychopharmacology Progress Notes Fall-Winter 1995-96).
This might be important for a few patients. But in general, factors of renal and hepatic metabolism are much more important in determining plasma levels. On the other hand, antacids (e.g., Maalox) can interfere with the absorption of antipsychotic agents and some benzodiazepines (see Ciraulo et al, Drug Interactions in Psychiatry, 1995). Smoking and alcohol can also alter plasma levels of psychotropic levels. One safeguard is to check plasma levels whenever abnormal absorption (or metabolism) is suspected.
In answer to your second question, I am not sure what you have observed upon switching patients from an SSRI to Serzone. Serzone [nefazodone], of course, is not pharmacologically identical with the SSRIs; it has 5HT2 receptor blocking effects (similar to, e.g., risperidone), which may confer different clinical properties; e.g., some clinicians have noticed an “activating” effect with nefazodone, despite its overall good record in reducing anxiety. It is also theoretically possible that an SSRI that inhibits the cytochrome 3A4, or 2D6, system could cause elevated levels of nefazodone and/or its anxiogenic metabolite, mCPP (see Schatzberg in ASCP notes, referenced above). Thus, it may be prudent to have a 3-5 day washout phase of short-acting SSRIs (paroxetine, sertraline) and longer washout of fluoxetine, prior to starting nefazodone.