Dihydroergotamine

INDICATIONS AND USAGE Dihydroergotamine Mesylate Injection is indicated for the acute treatment of migraine headaches with or without aura and the acute treatment of cluster headache episodes.

CLINICAL PHARMACOLOGY Mechanism of Action Dihydroergotamine binds with high affinity to 5-HT 1Dα and 5-HT 1Dβ receptors. It also binds with high affinity to serotonin 5-HT 1A , 5-HT 2A , and 5-HT 2C receptors, noradrenaline α 2A , α 2B and α 1 receptors, and dopamine D 2L and D 3 receptors. The therapeutic activity of dihydroergotamine in migraine is generally attributed to the agonist effect at 5-HT 1D receptors. Two current theories have been proposed to explain the efficacy of 5-HT 1D receptor agonists in migraine. One theory suggests that activation of 5-HT 1D receptors located on intracranial blood vessels, including those on arterio-venous anastomoses, leads to vasoconstriction, which correlates with the relief of migraine headache. The alternative hypothesis suggests that activation of 5-HT 1D receptors on sensory nerve endings of the trigeminal system results in the inhibition of pro-inflammatory neuropeptide release. In addition, dihydroergotamine possesses oxytocic properties. Pharmacokinetics Absorption Absolute bioavailability for the subcutaneous and intramuscular route have not been determined, however, no difference was observed in dihydroergotamine bioavailability from intramuscular and subcutaneous doses. Dihydroergotamine mesylate is poorly bioavailable following oral administration. Distribution Dihydroergotamine mesylate is 93% plasma protein bound. The apparent steady-state volume of distribution is approximately 800 liters. Metabolism Four dihydroergotamine mesylate metabolites have been identified in human plasma following oral administration. The major metabolite, 8´-β-hydroxydihydroergotamine, exhibits affinity equivalent to its parent for adrenergic and 5-HT receptors and demonstrates equivalent potency in several venoconstrictor activity models, in vivo and in vitro . The other metabolites, (i.e., dihydrolysergic acid, dihydrolysergic amide) and a metabolite formed by oxidative opening of the proline ring are of minor importance. Following nasal administration, total metabolites represent only 20% to 30% of plasma AUC. Quantitative pharmacokinetic characterization of the four metabolites has not been performed. Excretion The major excretory route of dihydroergotamine is via the bile in the feces. The total body clearance is 1.5 L/min which reflects mainly hepatic clearance. Only 6% to 7% of unchanged dihydroergotamine is excreted in the urine after intramuscular injection. The renal clearance (0.1 L/min) is unaffected by the route of dihydroergotamine administration. The decline of plasma dihydroergotamine after intramuscular or intravenous administration is multi-exponential with a terminal half-life of about 9 hours. Subpopulations No studies have been conducted on the effect of renal or hepatic impairment, gender, race, or ethnicity on dihydroergotamine pharmacokinetics. Dihydroergotamine Mesylate Injection is contraindicated in patients with severely impaired hepatic or renal function. (See CONTRAINDICATIONS .) Inte

DOSAGE AND ADMINISTRATION Dihydroergotamine Mesylate Injection should be administered in a dose of 1 mL intravenously, intramuscularly or subcutaneously. The dose can be repeated, as needed, at 1 hour intervals to a total dose of 3 mL for intramuscular or subcutaneous delivery or 2 mL for intravenous delivery in a 24 hour period. The total weekly dosage should not exceed 6 mL. Dihydroergotamine Mesylate Injection should not be used for chronic daily administration.

ADVERSE REACTIONS Serious cardiac events, including some that have been fatal, have occurred following use of Dihydroergotamine Mesylate Injection but are extremely rare. Events reported have included coronary artery vasospasm, transient myocardial ischemia, myocardial infarction, ventricular tachycardia, and ventricular fibrillation. (See CONTRAINDICATIONS , WARNINGS , and PRECAUTIONS .). Fibrotic complications have been reported in association with long term use of injectable dihydroergotamine mesylate (See WARNINGS: Fibrotic Complications ). Post-introduction Reports The following events derived from postmarketing experience have been occasionally reported in patients receiving Dihydroergotamine Mesylate Injection: vasospasm, paraesthesia, hypertension, dizziness, anxiety, dyspnea, headache, flushing, diarrhea, rash, increased sweating, and pleural and retroperitoneal fibrosis after long-term use of dihydroergotamine. Extremely rare cases of myocardial infarction and stroke have been reported. A causal relationship has not been established. Dihydroergotamine Mesylate Injection is not recommended for prolonged daily use. (See DOSAGE AND ADMINISTRATION .) To report SUSPECTED ADVERSE REACTIONS, contact Gland Pharma at 609-250-7990 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch.

WARNINGS Dihydroergotamine Mesylate Injection should only be used where a clear diagnosis of migraine headache has been established. CYP3A4 Inhibitors (e.g. Macrolide Antibiotics and Protease Inhibitors) There have been rare reports of serious adverse events in connection with the coadministration of dihydroergotamine and potent CYP3A4 inhibitors, such as protease inhibitors and macrolide antibiotics, resulting in vasospasm that led to cerebral ischemia and/or and ischemia of the extremities. The use of potent CYP3A4 inhibitors with dihydroergotamine should therefore be avoided (see CONTRAINDICATIONS ). Examples of some of the more potent CYP3A4 inhibitors include: anti-fungals ketoconazole and itraconazole, the protease inhibitors ritonavir, nelfinavir, and indinavir, and macrolide antibiotics erythromycin, clarithromycin, and troleandomycin. Other less potent CYP3A4 inhibitors should be administered with caution. Less potent inhibitors include saquinavir, nefazodone, fluconazole, grapefruit juice, fluoxetine, fluvoxamine, zileuton, and clotrimazole. These lists are not exhaustive, and the prescriber should consider the effects on CYP3A4 of other agents being considered for concomitant use with dihydroergotamine. Fibrotic Complication There have been reports of pleural and retroperitoneal fibrosis in patients following prolonged daily use of injectable dihydroergotamine mesylate. Rarely, prolonged daily use of other ergot alkaloid drugs has been associated with cardiac valvular fibrosis. Rare cases have also been reported in association with the use of injectable dihydroergotamine mesylate; however, in those cases, patients also received drugs known to be associated with cardiac valvular fibrosis. Administration of Dihydroergotamine Mesylate Injection should not exceed the dosing guidelines and should not be used for chronic daily administration ( see DOSAGE AND ADMINISTRATION ). Risk of Myocardial Ischemia and/or Infarction and Other Adverse Cardiac Events Dihydroergotamine Mesylate Injection should not be used by patients with documented ischemic or vasospastic coronary artery disease. ( See CONTRAINDICATIONS ) . It is strongly recommended that Dihydroergotamine Mesylate Injection, USP not be given to patients in whom unrecognized coronary artery disease (CAD) is predicted by the presence of risk factors (e.g., hypertension, hypercholesterolemia, smoker, obesity, diabetes, strong family history of CAD, females who are surgically or physiologically postmenopausal, or males who are over 40 years of age) unless a cardiovascular evaluation provides satisfactory clinical evidence that the patient is reasonably free of coronary artery and ischemic myocardial disease or other significant underlying cardiovascular disease. The sensitivity of cardiac diagnostic procedures to detect cardiovascular disease or predisposition to coronary artery vasospasm is modest, at best. If, during the cardiovascular evaluation, the patient’s medical history or electrocardiographic investigations reveal findings indicative of or consistent with coronary artery vasospasm or myocardial ischemia, Dihydroergotamine Mesylate Injection should not be administered. ( See CONTRAINDICATIONS . ) For patients with risk factors predictive of CAD who are determined to have a satisfactory cardiovascular evaluation, it is strongly recommended that administration of the first dose of Dihydroergotamine Mesylate Injection take place in the setting of a physician’s office or similar medically staffed and equipped facility unless the patient has previously received dihydroergotamine mesylate. Because cardiac ischemia can occur in the absence of clinical symptoms, consideration should be given to obtaining on the first occasion of use an electrocardiogram (ECG) during the interval immediately following Dihydroergotamine Mesylate Injection in those patients with risk factors. It is recommended that patients who are intermittent long-term users of Dihydroergotamine Mesylate

CONTRAINDICATIONS There have been a few reports of serious adverse events associated with the coadministration of dihydroergotamine and potent CYP3A4 inhibitors, such as protease inhibitors and macrolide antibiotics, resulting in vasospasm that led to cerebral ischemia and/or ischemia of the extremities. The use of potent CYP3A4 inhibitors (i.e., ritonavir, nelfinavir, indinavir, erythromycin, clarithromycin, troleandomycin, ketoconazole, itraconazole) with dihydroergotamine is, therefore contraindicated (See WARNINGS: CYP3A4 Inhibitors ). Dihydroergotamine Mesylate Injection should not be given to patients with ischemic heart disease (e.g., angina pectoris, history of myocardial infarction, or documented silent ischemia) or to patients who have clinical symptoms or findings consistent with coronary artery vasospasm including Prinzmetal’s variant angina. (See WARNINGS .) Because Dihydroergotamine Mesylate Injection may increase blood pressure, it should not be given to patients with uncontrolled hypertension. Dihydroergotamine Mesylate Injection 5-HT1 agonists (e.g., sumatriptan), ergotamine-containing or ergot-type medications or methysergide should not be used within 24 hours of each other. Dihydroergotamine Mesylate Injection should not be administered to patients with hemiplegic or basilar migraine. In addition to those conditions mentioned above, Dihydroergotamine Mesylate Injection is also contraindicated in patients with known peripheral arterial disease, sepsis, following vascular surgery and severely impaired hepatic or renal function. Dihydroergotamine Mesylate Injection is contraindicated in patients who have previously shown hypersensitivity to ergot alkaloids. Dihydroergotamine mesylate should not be used with peripheral and central vasoconstrictors because the combination may result in additive or synergistic elevation of blood pressure.

OVERDOSAGE To date, there have been no reports of acute overdosage with this drug. Due to the risk of vascular spasm, exceeding the recommended dosages of Dihydroergotamine Mesylate Injection is to be avoided. Excessive doses of dihydroergotamine may result in peripheral signs and symptoms of ergotism. Treatment includes discontinuance of the drug, local application of warmth to the affected area, the administration of vasodilators, and nursing care to prevent tissue damage. In general, the symptoms of an acute Dihydroergotamine Mesylate Injection overdose are similar to those of an ergotamine overdose, although there is less pronounced nausea and vomiting with Dihydroergotamine Mesylate Injection. The symptoms of an ergotamine overdose include the following: numbness, tingling, pain, and cyanosis of the extremities associated with diminished or absent peripheral pulses; respiratory depression; an increase and/or decrease in blood pressure, usually in that order; confusion, delirium, convulsions, and coma; and/or some degree of nausea, vomiting, and abdominal pain. In laboratory animals, significant lethality occurs when dihydroergotamine is given at I.V. doses of 44 mg/kg in mice, 130 mg/kg in rats, and 37 mg/kg in rabbits. Up-to-date information about the treatment of overdosage can often be obtained from a certified Regional Poison Control Center. Telephone numbers of certified Poison Control Centers are listed in the Physician’s Desk Reference (PDR).*