Posted by Sunnely on March 9, 2001, at 16:32:30
In reply to Re: Ziprasidone: Not so fast. » Sunnely, posted by SLS on March 9, 2001, at 9:51:19
Hi Scott,
If you are a young healthy individual without pre-existing heart disease, the combination of nortriptyline (blood level at therapeutic range) and Geodon (at recommended dose) is considered generally safe.
Most of the prolonged QTc I encountered with the use of tricyclic antidepressants are with the elderly people and in those who intentional overdosed (suicide attempts). In one case, a 62 year-old-female who consumed alcohol then overdosed on Elavil (further metabolized to nortriptlyline) estimated over 1000 mg, developed a prolonged QTc but unfortunately progressed to "torsades" which further deteriorated into ventricular fibrillation. Emergency measures instituted failed to revive her.
What is prolongation of QTc? In normal heart conduction, the QTc interval lasts approximately 420 ms (milliseconds). However, if repolarization is delayed, prolongation of the QT interval results. In general, a QTc longer than 450 ms is of potential concern. Prolongation longer than 500 ms indicates an elevated risk of progression to tachyarrhythmias ("torsades des pointes"), which may be associated with symptoms such as palpitations, dizziness, lightheadedness, and syncope; and progression to ventricular fibrillation, which can potentially cause sudden death. Prolonged QTc in itself is not the main problem. However, this ECG abnormality is considered a "harbinger" to a more serious arrhythmia ("torsades") and even sudden death. (If you are on Geodon, it is important to immediately notify your doctor if you experience palpitations, dizziness, lightheadedness, and syncope.)
Aside from the elderly, other risk factors to the development of prolonged QTc include the following:
1. Electrolyte imbalance (particularly low potassium or magnesium levels). This may result from diuretic and excessive vomiting/diarrhea. (People with eating disorders may be more prone).
2. Genetic - Those born with long QT syndrome.
3. Heart disease such as acute or chronic myocardial ischemia, heart rhythm irregularities (arrhythmias), and congestive heart failure.
4. Drugs known to prolong QTc interval such as thioridazine (Mellaril), mesoridazine (Serentil) which is a metabolite of Mellaril, sertindole (Serlect), terfenadine (Seldane), astemizole (Hismanal), grepafloxacin (Raxar), and cisapride (Propulsid).
5. Medication overdose with drugs that prolong QTc. (Tricyclics may cause prolonged QTc in overdoses. It is important to monitor ECG and the tricyclic blood levels. Potentially serious effects on the heart from tricyclic overdoses could last from 1-5 days.)
6. Drug-drug or drug-drink interactions. Some of the reported sudden deaths from the use of Seldane and Hismanal (both removed from the US market) were taken with grapefruit juice (GJ). Although Pfizer does not indicate this in their package insert (PI) and there is no study regarding this combination, it is probably clinically prudent to avoid GJ while one is on Geodon since GJ is a potent inhibitor of the enzyme CYP3A4, the same enzyme that Geodon depends on for metabolism. There are other drugs that are known to potent inhibitors of CYP3A4, therefore you should consult with your doctor or pharmacist before combining them with Geodon.
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> Dear Sunnely,
>
> Regarding cardiac function, what are your thoughts about combining Geodon with a tricyclic antidepressant? I am considering adding it to nortriptyline.
>
> Thanks.
>
>
> - Scott
poster:Sunnely
thread:54700
URL: http://www.dr-bob.org/babble/20010302/msgs/56037.html