A QT interval is the time period taken by the heart’s electrical system to send an impulse through the ventricles and recharge thereafter. A normal QT interval ranges between 0.36 and 0.44 seconds, but it varies depending on heart rate, age, and gender. In females, the QT interval is prolonged if it is greater than 450 ms while in males the QT interval is prolonged if it’s greater than 470ms. When the QT interval is greater than 500 ms, then one is at risk of a Torsades de Pointes, which is a tachycardia condition. People with prolonged QT interval have an ailment known as long QT syndrome which is either congenital or acquired. Congenital long QT syndrome is due to inherited family genes whilst acquired long QT syndrome is caused by certain medication.
Acquired Long QT Syndrome
Acquired long QT syndrome is associated with certain medications which can cause QT interval prolongations. Some of the medications associated with the condition include antihistamines, antibiotics, antifungal drugs, antiarrhythmic drugs, and even antipsychotic drugs. Many of the drugs under the mentioned medication families interfere with the ion channels which in turn affects the heart’s electrical activity. This can further lead to an arrhythmia – a problem related to the rhythm of the heartbeat. The main problem is often blockage of the inward potassium rectifier (IKr or HERG) channel. It is responsible for the crucial rapid delayed rectifier potassium current in the third phase of repolarization of the cardiac action potential. Medication linked to prolong QT also act on the same potassium channel hence making it susceptible to the effects of the drugs.
Does Reglan Prolong QT Interval?
It is important that you let your doctor know if you have any congestive heart conditions including heart rhythm disorders. Reglan, rather metoclopramide has been thought to have pharmacological characteristics that can result in prolonged QT interval. The exact mechanism is unknown but there are a few reasonable arguments as to why Reglan can prolong QT. The drug can affect the D2 receptor antagonism which in turn implicates the sympathovagal balance within the heart. It can also cause blockage of potassium current which can prolong repolarization thus lengthening the QT interval. Metoclopramide can also have an agonist activity on the 5-HT4 receptor, which is similar to Cisapride’s activity that is known to cause QT prolongation. In short, Reglan can increase the QT/RR slope and QT variance hence increased the risk of prolonged QT interval and Torsades de Pointes.
What is Reglan?
Reglan (Metoclopramide) is an antiemetic drug used in treating vomiting, nausea, heartburn, loss of appetite and earl feeling of fullness. It works by increasing muscle contractions in the upper digestive tract thus speeding up the rate which the stomach empties into the intestine. This, in turn, helps decrease chances of heartburns and relieves stomach discomfort after eating. Metoclopramide therapy has been related to a serious movement disorder i.e. tardive dyskinesia, which is an irreversible condition.
It has no cure, thus if you experience any symptoms of the condition, the medication should be terminated immediately. The use of Reglan is recommended for adults only and should not be used for longer than 12 weeks. It can either be administered orally or by IV or by IM.
Common Side Effects of Reglan
Drugs usually have a number of side effects, but they are not imminent in all patients. In addition to that, the extent of the severity of side effects is dependent on the patient and other risk factors which may not favor the patient. The common side effects of Reglan include:
- Tiredness and fatigue
- Diarrhea
- Dizziness
- Restlessness and agitation
- Headache
- Nausea and vomiting
- Frequent urination
- Breast tenderness or swelling
- Changes in menstrual periods
Conclusion
Reglan (metoclopramide) does lead to prolonged QT interval which increased the risk of heart arrhythmias and Torsades de Pointes. The consequence of the drug has been linked to the pharmacological traits of the drug which creates an environment where it can cause prolongation of the QT interval. Drug-induced long QT syndrome can be triggered by metoclopramide, so you should be careful with its prescription. Follow the doctor’s advice and any recommendations given with the medication. Other than that, avoid the medication completely if you have any heart complications, and go for antiemetic drugs that will not prolong QT interval.
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