This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.
Severe. These medicines may interact and cause very harmful effects and are usually not taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.
How the interaction occurs:
Pindolol and propranolol may slow down how quickly your liver processes thioridazine. Thioridazine may slow down how quickly your liver processes pindolol and propranolol.
What might happen:
The blood levels of one or both medicines may be increased. This may cause an increase in both the beneficial, as well as toxic effects of these medicines, including potentially life-threatening changes in your heart's rhythm.
What you should do about this interaction:
Contact your healthcare professionals (e.g. doctor or pharmacist) right away about using these medications together. Your doctor may want to change your medicine. If your doctor decides that these are the best medicines for you to be on, be sure to tell your doctor if you notice an irregular heartbeat or have any dizziness or fainting episodes. You should check your blood pressure regularly. Tell your doctor if there is a change in your blood pressure, since the dose of your beta-blocker may need to be adjusted. You should also tell your doctor if you have any chest pain, shortness of breath, or if your heartbeat becomes slow. If you have blurred vision, contact your doctor.It may be necessary to adjust the dosage of either medicine when starting or stopping the other medicine.Make sure that your doctor knows all of the medicines that you are taking.Your healthcare professionals (e.g. doctor or pharmacist) may already be aware of this interaction and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first.
1.Thioridazine tablet, US prescribing information. Mylan Pharmaceuticals September, 2010.
2.Silver JM, Yudofsky SC, Kogan M, Katz BL. Elevation of thioridazine plasma levels by propranolol. Am J Psychiatry 1986 Oct;143(10):1290-2.
3.Greendyke RM, Gulya A. Effect of pindolol administration on serum levels of thioridazine, haloperidol, phenytoin, and phenobarbital. J Clin Psychiatry 1988 Mar;49(3):105-7.