Prozac

Question:
I'm an instructor and would like your opinion on some medicines that are taken by one of my students.
The person has been tested by a doctor who said it was no problem for her to dive with Prozac which is an anti-depressant. Could you let me know whether I should exclude this person from diving because of her use of Prozac or is it still possible to dive but with restrictions like depth, and time. As far as my medical knowledge reaches I am under the opinion that it is not allowed to dive with anti depressants. (but maybe this is an old point of view and I want to be sure about this before confronting my student).

Answer:
Prozac (Fluoxetin) is a drug with known negative interactions with alcohol and other sedative drugs (tranquilizers). As such it is also possible that negative interactions (synergetic action enhancement) take place with increased partial pressures of nitrogen at depth, with a potentially increased risk of nitrogen narcosis. Also a prolongation of convulsions has been observed in patients treated with electro-convulsive treatment, suggesting a form of increased response to situations the may potentially stimulate convulsions ( increased oxygen partial pressures, hyperventilation,...)
Furthermore, it is frequently the condition for which the drug is taken that may be itself a contraindication to diving, like with any situation linked to psychological disturbances.
Fluoxetin half life is of medium duration ( it is not a very short acting drug ) and the blood levels tend to stay within the therapeutical range for several hours. Since the assumption of the drug is normally prescribed in the morning, any diving activity would take place during the period of maximal pharmacological action. An alternative solution, that should however be discussed with the treating physician, could be to modify the treatment schedule in a way to take the drug after the day's diving activities, thus allowing the evening and the entire night for the drug's plasma levels to decrease.