Drug Interactions between Lopressor HCT and pentazocine

Using metoprolol and hydroCHLOROthiazide together may lower your blood pressure and slow your heart rate. This can cause dizziness, or feeling like you might pass out, weakness, fainting, fast or irregular heartbeats, or loss of blood glucose control. If you take both medications together, tell your doctor if you have any of these symptoms. You may need a dose adjustment or need your blood pressure checked more often to safely use both medications. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Metoprolol and pentazocine may have additive effects in lowering your blood pressure. You may experience headache, dizziness, lightheadedness, fainting, and/or changes in pulse or heart rate. These side effects are most likely to be seen at the beginning of treatment, following a dose increase, or when treatment is restarted after an interruption. Let your doctor know if you develop these symptoms and they do not go away after a few days or they become troublesome. Avoid driving or operating hazardous machinery until you know how the medications affect you, and use caution when getting up from a sitting or lying position. It is important to tell your doctor about all other medications you use, including vitamins and herbs. Do not stop using any medications without first talking to your doctor.

Consumer information for this interaction is not currently available.

MONITOR: Opioids exhibit hypotensive effects, especially during initiation of therapy and dose escalation. Coadministration with diuretics may lead to an increased risk of hypotension. In contrast, opioids may also decrease the efficacy of diuretics as they may trigger the secretion of antidiuretic hormone, although the proposed mechanism for this interaction is unclear and clinical studies are not currently available.

MANAGEMENT: Caution and close monitoring for development of hypotension in addition to decreased diuretic efficacy are advised during coadministration of these agents. Blood pressure should be monitored throughout therapy and dose adjustment of the diuretic should be considered. Patients should be advised to avoid rising abruptly from a sitting or recumbent position and to notify their physician if they experience dizziness, lightheadedness, syncope, orthostasis, or tachycardia. Patients should also avoid driving or operating hazardous machinery until they know how the medications affect them.