Maddison asked
Hi, I'm on hydromorphone 2 mg up to 3x a day for spinal injury, I also take 200 mg of Lamactil for a mood disorder and was put on fluoxetine 20 mg recently. It seems to me this combo isn't a great idea. What do you think?
Answer
There are some potential interactions between fluoxetine (brand name Prozac), hydromorphone and Lamictal, as discussed below.
Prozac (Fluoxetine) And Hydromorphone
Many sources list the interaction between fluoxetine and hydromorphone as severe but there isn't much documented evidence of this.
Fluoxetine is a potent inhibitor of the metabolizing enzyme CYP2D6. Drugs which are metabolized by CYP2D6 may have their concentrations significantly increased in the body when taken with fluoxetine (due to the inhibition of their metabolism).
However, hydromorphone does not appear to be extensively metabolized, if at all, by CYP2D6, according to most studies and the prescribing information for the drug. Therefore, CYP2D6 inhibition from fluoxetine shouldn't affect levels of hydromorphone significantly.
Nevertheless, there have been anecdotal reports of increased side effects when taking both hydromorphone and fluoxetine together. If they are taken together, you want to be on the lookout for an exaggerated response to hydromorphone.
In addition to the potential for increased hydromorphone levels, there is a blanket precaution with all opioids (such as hydromorphone) and drugs the increase serotonin levels (such as fluoxetine). The combination could potentially cause serotonin syndrome. In fact, the FDA released a safety communication regarding the combination of these drugs.
Serotonin syndrome is a rare but serious disorder that is characterized by too high levels of serotonin in the brain. Symptoms include:
- Chills
- Anxiety
- Agitation
- Elevated blood pressure
- Tremors
- Palpitations
- Coma
Serotonin syndrome is rare but important to be aware of as it should be treated as an emergency if it does happen.
Lamictal, Prozac And Hydromorphone
All of these drugs have CNS (central nervous system) depressant effects. Caution is advised when combining CNS depressants as there can be an increase in sedation and dizziness. Rarely, respiratory depression (i.e. shallow breathing) can occur.
It is important to start on low doses of any new medication being added to your therapy and be monitored for side effects.
It is important to understand that most drug therapies involve the potential for certain side effects and interactions. That doesn't mean that the medications shouldn't be used together, just that it is important to know what to look out for in terms of effectiveness and adverse events. If you are concerned about potential side effects, are experiencing them or are not having good effects from your medication, be sure to talk to your doctor.
Summary
- Prozac (fluoxetine) may increase hydromorphone levels, but this interaction isn't well documented.
- The combination of any medication that increases serotonin (e.g. fluoxetine) should be used with caution with opioid medications due to the increased risk of serotonin syndrome.
- Lamictal, fluoxetine and hydromorphone are all CNS depressants and may increase the risk of additive sedation.
