Drug Interactions between polyethylene glycol 3350 with electrolytes and pseudoephedrine / terfenadine

Terfenadine can cause an irregular heart rhythm that may be serious and potentially life-threatening, although it is a relatively rare side effect. The risk is increased if you have low blood levels of magnesium or potassium, which can occur with bowel cleansing preparations or excessive use of medications that have a laxative effect. You should use polyethylene glycol 3350 with electrolytes exactly as prescribed by your doctor, and drink plenty of clear liquids before, during, and after the cleansing process to avoid becoming dehydrated. Talk to your doctor if you have any questions or concerns. Your doctor may be able to recommend specific fluids you can drink before starting polyethylene glycol 3350 with electrolytes to help maintain your electrolyte levels. He/she may also want to monitor your electrolyte levels and/or heart rhythm. You should seek immediate medical attention if you develop sudden dizziness, lightheadedness, fainting, shortness of breath, or heart palpitations during treatment with these medications. In addition, you should let your doctor know if you experience signs and symptoms of low electrolyte levels such as weakness, tiredness, drowsiness, dizziness, confusion, tingling, numbness, muscle pain, cramps, nausea, or vomiting. 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: The risk of seizures induced by the use of bowel cleansing preparations may be increased in patients on concomitant medications that can lower the seizure threshold such as selective serotonin reuptake inhibitors (SSRI antidepressants or anorectics), monoamine oxidase inhibitors, neuroleptic agents, central nervous system stimulants, opioids, tricyclic antidepressants, other tricyclic compounds (e.g., cyclobenzaprine, phenothiazines), systemic steroids, carbapenems, cholinergic agents, fluoroquinolones, interferons, chloroquine, mefloquine, lindane, and theophylline. Rare cases of generalized tonic-clonic seizures and/or loss of consciousness in association with low serum osmolality and electrolyte abnormalities (e.g., hyponatremia, hypokalemia, hypocalcemia, hypomagnesemia) have been reported with the use of bowel cleansing products in patients with no prior history of seizures. The condition resolved with correction of fluid and electrolyte abnormalities.

MANAGEMENT: Caution is advised when bowel cleansing preparations are prescribed in patients treated with agents that can lower the seizure threshold. Bowel cleansing preparations should not be used if these patients have impaired renal function or perfusion, dehydration, or uncorrected electrolyte abnormalities. Baseline and postprocedure labs including serum electrolytes, calcium, phosphate, BUN, and creatinine should be considered, particularly in the elderly. Patients should be advised not to exceed the recommended dosage of their bowel cleansing preparation and to drink sufficient quantities of clear fluids before, during, and after the bowel preparation process. Administration of an electrolyte rehydration solution may help attenuate the electrolyte abnormalities and hypovolemia.