DIHYDROERGOTAMINE MESYLATE- dihydroergotamine mesylate injection
Hikma Pharmaceuticals USA Inc.
WARNING: PERIPHERAL ISCHEMIA FOLLOWING COADMINISTRATION WITH POTENT CYP3A4 INHIBITORS
Serious and/or life-threatening peripheral ischemia has been associated with the coadministration of DIHYDROERGOTAMINE with potent CYP3A4 inhibitors including protease inhibitors and macrolide antibiotics. Because CYP3A4 inhibition elevates the serum levels of DIHYDROERGOTAMINE, the risk for vasospasm leading to cerebral ischemia and/or ischemia of the extremities is increased. Hence, concomitant use of these medications is contraindicated. (See CONTRAINDICATIONS and WARNINGS )
Dihydroergotamine Mesylate Injection, USP is ergotamine hydrogenated in the 9, 10 position as the mesylate salt. Dihydroergotamine Mesylate Injection, USP is known chemically as ergotaman-3´,6´,18-trione,9,10-dihydro-12´-hydroxy-2´-methyl-5´-(phenylmethyl)-,(5´α)-, monomethanesulfonate. Its molecular weight is 679.80 and its empirical formula is C33 H37 N5 O5 •CH4 O3 S.
The chemical structure is
C33 H37 N5 O5 •CH4 O3 S Mol. wt. 679.80
Dihydroergotamine Mesylate Injection, USP is a clear, colorless solution supplied in sterile ampules for intravenous, intramuscular, or subcutaneous administration. Each mL contains 1 mg Dihydroergotamine Mesylate, USP; Alcohol, USP 6.1% by volume; Glycerin, USP 15% by weight; Water for Injection, USP; Methanesulfonic Acid and/or Sodium Hydroxide for pH adjustment (pH range is 3.4 to 4.9).
Dihydroergotamine binds with high affinity to 5-HT1D α and 5-HT1D β receptors. It also binds with high affinity to serotonin 5-HT1A , 5-HT2A , and 5-HT2C receptors, noradrenaline α2A , α2B and α1 receptors, and dopamine D2L and D3 receptors.
The therapeutic activity of dihydroergotamine in migraine is generally attributed to the agonist effect at 5-HT1D receptors. Two current theories have been proposed to explain the efficacy of 5-HT1D receptor agonists in migraine. One theory suggests that activation of 5-HT1D receptors located on intracranial blood vessels, including those on arteriovenous anastomoses, leads to vasoconstriction, which correlates with the relief of migraine headache. The alternative hypothesis suggests that activation of 5-HT1D receptors on sensory nerve endings of the trigeminal system results in the inhibition of pro-inflammatory neuropeptide release.
In addition, dihydroergotamine possesses oxytocic properties.
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.
Dihydroergotamine mesylate is 93% plasma protein bound. The apparent steady-state volume of distribution is approximately 800 liters.
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.
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.
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).
Pharmacokinetic interactions have been reported in patients treated orally with other ergot alkaloids (e.g., increased levels of ergotamine) and macrolide antibiotics, principally troleandomycin, presumably due to inhibition of cytochrome P4503A metabolism of the alkaloids by troleandomycin. Dihydroergotamine has also been shown to be an inhibitor of cytochrome P4503A catalyzed reactions and rare reports of ergotism have been obtained from patients treated with dihydroergotamine and macrolide antibiotics (e.g., troleandomycin, clarithromycin, erythromycin), and in patients treated with dihydroergotamine and protease inhibitors (e.g., ritonavir), presumably due to inhibition of cytochrome P4503A metabolism of ergotamine (See CONTRAINDICATIONS). No pharmacokinetic interactions involving other cytochrome P450 isoenzymes are known.
Dihydroergotamine Mesylate Injection, USP is indicated for the acute treatment of migraine headaches with or without aura and the acute treatment of cluster headache episodes.
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.
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