Effects on Cardiac Conduction

A dose-dependent prolongation of the QT interval was observed within 10 minutes of droperidol administration in a study of 40 patients without known cardiac disease who underwent extracranial head and neck surgery. Significant QT prolongation was observed at all three dose levels evaluated, with 0.1, 0.175, and 0.25 mg/kg associated with prolongation of median QTc by 37, 44, and 59 msec, respectively.

Cases of QT prolongation and serious arrhythmias (e.g. torsade de pointes, ventricular arrythmias, cardiac arrest, and death) have been observed during post-marketing treatment with INAPSINE. Some cases have occurred in patients with no known risk factors and at doses at or below recommended doses. There has been at least one case of nonfatal torsade de pointes confirmed by rechallenge.

Based on these reports, all patients should undergo a 12-lead ECG prior to administration of INAPSINE to determine if a prolonged QT interval (i.e., QTc greater than 440 msec for males or 450 msec for females) is present. If there is a prolonged QT interval, INAPSINE should NOT be administered. For patients in whom the potential benefit of INAPSINE treatment is felt to outweigh the risks of potentially serious arrhythmias, ECG monitoring should be performed prior to treatment and continued for 2 to 3 hours after completing treatment to monitor for arrhythmias.

FLUIDS AND OTHER COUNTERMEASURES TO MANAGE HYPOTENSION SHOULD BE READILY AVAILABLE.

As with other CNS depressant drugs, patients who have received INAPSINE (droperidol) should have appropriate surveillance.

It is recommended that opioids, when required, initially be used in reduced doses.

As with other neuroleptic agents, very rare reports of neuroleptic malignant syndrome (altered consciousness, muscle rigidity and autonomic instability) have occurred in patients who have received INAPSINE (droperidol).

Since it may be difficult to distinguish neuroleptic malignant syndrome from malignant hyperpyrexia in the perioperative period, prompt treatment with dantrolene should be considered if increases in temperature, heart rate or carbon dioxide production occur.

General

The initial dose of INAPSINE (droperidol) should be appropriately reduced in elderly, debilitated and other poor-risk patients. The effect of the initial dose should be considered in determining incremental doses.

Certain forms of conduction anesthesia, such as spinal anesthesia and some peridural anesthetics, can alter respiration by blocking intercostal nerves and can cause peripheral vasodilatation and hypotension because of sympathetic blockade. Through other mechanisms (see CLINICAL PHARMACOLOGY), INAPSINE can also alter circulation. Therefore, when INAPSINE is used to supplement these forms of anesthesia, the anesthetist should be familiar with the physiological alterations involved, and be prepared to manage them in the patients elected for these forms of anesthesia.

If hypotension occurs, the possibility of hypovolemia should be considered and managed with appropriate parenteral fluid therapy. Repositioning the patient to improve venous return to the heart should be considered when operative conditions permit. It should be noted that in spinal and peridural anesthesia, tilting the patient into a head-down position may result in a higher level of anesthesia than is desirable, as well as impair venous return to the heart. Care should be exercised in moving and positioning of patients because of a possibility of orthostatic hypotension. If volume expansion with fluids plus these other countermeasures do not correct the hypotension, then the administration of pressor agents other than epinephrine should be considered. Epinephrine may paradoxically decrease the blood pressure in patients treated with INAPSINE due to the alpha-adrenergic blocking action of INAPSINE.

Since INAPSINE may decrease pulmonary arterial pressure, this fact should be considered by those who conduct diagnostic or surgical procedures where interpretation of pulmonary arterial pressure measurements might determine final management of the patient.

Vital signs and ECG should be monitored routinely.

When the EEG is used for postoperative monitoring, it may be found that the EEG pattern returns to normal slowly.

Drug Interactions

Carcinogenesis, Mutagenesis, Impairment of Fertility

No carcinogenicity studies have been carried out with INAPSINE. The micronucleus test in female rats revealed no mutagenic effects in single oral doses as high as 160 mg/kg. An oral study in rats (Segment I) revealed no impairment of fertility in either male or females at 0.63, 2.5 and 10 mg/kg doses (approximately 2.9 and 36 times maximum recommended human iv/im dosage).

Pregnancy

Labor and Delivery

There are insufficient data to support the use of INAPSINE in labor and delivery. Therefore, such use is not recommended.

Nursing Mothers

It is not known whether INAPSINE is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when INAPSINE is administered to a nursing mother.

Pediatric Use

The safety of INAPSINE in children younger than two years of age has not been established.

Manifestations

The manifestations of INAPSINE (droperidol) overdosage are an extension of its pharmacologic actions and may include QT prolongation and serious arrhythmias (e.g., torsade de pointes) (see BOX WARNING, WARNINGS, and PRECAUTIONS).

Treatment

In the presence of hypoventilation or apnea, oxygen should be administered and respiration should be assisted or controlled as indicated. A patent airway must be maintained; an oropharyngeal airway or endotracheal tube might be indicated. The patient should be carefully observed for 24 hours; body warmth and adequate fluid intake should be maintained. If hypotension occurs and is severe or persists, the possibility of hypovolemia should be considered and managed with appropriate parenteral fluid therapy (see PRECAUTIONS).

If significant extrapyramidal reactions occur in the context of an overdose, an anticholinergic should be administered.

The intravenous Median Lethal Dose of INAPSINE is 20 to 43 mg/kg in mice; 30 mg/kg in rats; 25 mg/kg in dogs and 11 to 13 mg/kg in rabbits. The intramuscular Median Lethal Dose of INAPSINE is 195 mg/kg in mice; 104 to 110 mg/kg in rats; 97 mg/kg in rabbits and 200 mg/kg in guinea pigs.

Adult dosage

The maximum recommended initial dose of INAPSINE is 2.5 mg IM or slow IV. Additional 1.25 mg doses of INAPSINE may be administered to achieve the desired effect. However, additional doses should be administered with caution, and only if the potential benefit outweighs the potential risk.

Children's dosage

For children two to 12 years of age, the maximum recommended initial dose is 0.1 mg/kg, taking into account the patient's age and other clinical factors. However, additional doses should be administered with caution, and only if the potential benefit outweighs the potential risk.

See WARNINGS and PRECAUTIONS for use of INAPSINE with other CNS depressants and in patients with altered response.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit. If such abnormalities are observed, the drug should not be administered.

STORAGE

Store at 20° to 25°C (68° to 77°F). [See USP Controlled Room Temperature]. Protect from light.