Drug interactions between ibutilide and saquinavir
| Results for the following 2 drugs: |
|---|
| ibutilide |
| saquinavir |
Interactions between your selected drugs
saquinavir ↔ ibutilide
Applies to:saquinavir and ibutilide
GENERALLY AVOID: Saquinavir in combination with ritonavir may cause dose-related prolongation of the QT interval. Theoretically, coadministration with other agents that can prolong the QT interval may result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death. In a study of 59 healthy volunteers aged 18 to 55 years who were administered saquinavir/ritonavir at a therapeutic dosage of 1000 mg/100 mg twice daily and a supratherapeutic dosage of 1500 mg/100 mg twice daily, the maximum mean QT prolongation (QTcS; study-specific QT interval correction) on treatment day 3 was 18.9 msec for the lower dosage and 30.2 msec for the supratherapeutic dosage, compared to 12.2 msec for the active control (moxifloxacin 400 mg). The majority of subjects (89% and 80% in the therapeutic and supratherapeutic groups, respectively) had a QTcS less than 450 msec, and none had a QTc interval exceeding the potentially clinically relevant threshold of 500 msec. In general, the risk of an individual agent or a combination of agents causing ventricular arrhythmia in association with QT prolongation is largely unpredictable but may be increased by certain underlying risk factors such as congenital long QT syndrome, cardiac disease, and electrolyte disturbances (e.g., hypokalemia, hypomagnesemia). In addition, the extent of drug-induced QT prolongation is dependent on the particular drug(s) involved and dosage(s) of the drug(s).
MANAGEMENT: Ritonavir-boosted saquinavir should not be used with Class IA (e.g., disopyramide, quinidine, procainamide) or class III (e.g., amiodarone, dofetilide, sotalol) antiarrhythmic drugs or other drugs that may prolong the QT interval (e.g., cisapride; some neuroleptic agents; certain fluoroquinolones). Patients treated with any medication that can cause QT prolongation should be advised to seek medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes such as dizziness, lightheadedness, fainting, palpitations, irregular heartbeat, shortness of breath, or syncope.
See also...
Drug Interaction Classification
The classifications below are a guideline only. The relevance of a particular drug interaction to a specific patient is difficult to determine using this tool alone given the large number of variables that may apply.
| Major | Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit. |
| Moderate | Moderately clinically significant. Usually avoid combinations; use it only under special circumstances. |
| Minor | Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan. |
Do not stop taking any medications without consulting your healthcare provider.
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