D.h.e. 45 (Dihydroergotamine Mesylate) - Drug Interactions, Contraindications, Overdosage, etc

DRUG INTERACTIONS

Vasoconstrictors

D.H.E. 45^® (dihydroergotamine mesylate) Injection, USP should not be used with peripheral vasoconstrictors because the combination may cause synergistic elevation of blood pressure.

Sumatriptan

Sumatriptan has been reported to cause coronary artery vasospasm, and its effect could be additive with D.H.E. 45^® (dihydroergotamine mesylate) Injection, USP. Sumatriptan and D.H.E. 45^® (dihydroergotamine mesylate) Injection, USP should not be taken within 24 hours of each other. (See CONTRAINDICATIONS .)

Beta Blockers

Although the results of a clinical study did not indicate a safety problem associated with the administration of D.H.E. 45^® (dihydroergotamine mesylate) Injection, USP to subjects already receiving propranolol, there have been reports that propranolol may potentiate the vasoconstrictive action of ergotamine by blocking the vasodilating property of epinephrine.

Nicotine

Nicotine may provoke vasoconstriction in some patients, predisposing to a greater ischemic response to ergot therapy.

CYP 3A4 Inhibitors (e.g. Macrolide Antibiotics and Protease Inhibitors) See CONTRAINDICATIONS and WARNINGS .

SSRI’s

Weakness, hyperreflexia, and incoordination have been reported rarely when 5-HT₁ agonists have been co-administered with SSRI’s (e.g., fluoxetine, fluvoxamine, paroxetine, sertraline). There have been no reported cases from spontaneous reports of drug interaction between SSRI’s and D.H.E. 45^® (dihydroergotamine mesylate) Injection, USP.

Oral Contraceptives

The effect of oral contraceptives on the pharmacokinetics of D.H.E. 45^® (dihydroergotamine mesylate) Injection, USP has not been studied.

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 D.H.E. 45^® (dihydroergotamine mesylate) Injection, USP 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 D.H.E. 45^® (dihydroergotamine mesylate) Injection, USP overdose are similar to those of an ergotamine overdose, although there is less pronounced nausea and vomiting with D.H.E. 45^® (dihydroergotamine mesylate) Injection, USP. 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).*

CONTRAINDICATIONS

There have been a few reports of serious adverse events associated with the coadministration of dihydroergotamine and potent CYP 3A4 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 CYP 3A4 inhibitors (ritonavir, nelfinavir, indinavir, erythromycin, clarithromycin, troleandomycin, ketoconazole, itraconazole) with dihydroergotamine is, therefore contraindicated (See WARNINGS: CYP 3A4 Inhibitors ).

D.H.E. 45^® (dihydroergotamine mesylate) Injection, USP should not be given to patients with ischemic heart disease (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 D.H.E. 45^® (dihydroergotamine mesylate) Injection, USP may increase blood pressure, it should not be given to patients with uncontrolled hypertension.

D.H.E. 45^® (dihydroergotamine mesylate) Injection, USP, 5-HT₁ agonists (e.g., sumatriptan), ergotamine-containing or ergot-type medications or methysergide should not be used within 24 hours of each other.

D.H.E. 45^® (dihydroergotamine mesylate) Injection, USP should not be administered to patients with hemiplegic or basilar migraine.

In addition to those conditions mentioned above, D.H.E. 45^® (dihydroergotamine mesylate) Injection, USP is also contraindicated in patients with known peripheral arterial disease, sepsis, following vascular surgery and severely impaired hepatic or renal function.

D.H.E. 45^® (dihydroergotamine mesylate) Injection, USP may cause fetal harm when administered to a pregnant woman. Dihydroergotamine possesses oxytocic properties and, therefore, should not be administered during pregnancy. If this drug is used during pregnancy, or if the patient becomes pregnant while taking this drug, the patient should be apprised of the potential hazard to the fetus.

There are no adequate studies of dihydroergotamine in human pregnancy, but developmental toxicity has been demonstrated in experimental animals. In embryo-fetal development studies of dihydroergotamine mesylate nasal spray, intranasal administration to pregnant rats throughout the period of organogenesis resulted in decreased fetal body weights and/or skeletal ossification at doses of 0.16 mg/day (associated with maternal plasma dihydroergotamine exposures [AUC] approximately 0.4-1.2 times the exposures in humans receiving the MRDD of 4 mg) or greater. A no effect level for embryo-fetal toxicity was not established in rats. Delayed skeletal ossification was also noted in rabbit fetuses following intranasal administration of 3.6 mg/day (maternal exposures approximately 7 times human exposures at the MRDD) during organogenesis. A no effect level was seen at 1.2 mg/day (maternal exposures approximately 2.5 times human exposures at the MRDD). When dihydroergotamine mesylate nasal spray was administered intranasally to female rats during pregnancy and lactation, decreased body weights and impaired reproductive function (decreased mating indices) were observed in the offspring at doses of 0.16 mg/day or greater. A no effect level was not established. Effects on development occurred at doses below those that produced evidence of significant maternal toxicity in these studies. Dihydroergotamine-induced intrauterine growth retardation has been attributed to reduced uteroplacental blood flow resulting from prolonged vasoconstriction of the uterine vessels and/or increased myometrial tone.

D.H.E. 45^® (dihydroergotamine mesylate) Injection, USP is contraindicated in patients who have previously shown hypersensitivity to ergot alkaloids.

Dihydroergotamine mesylate should not be used by nursing mothers. (See PRECAUTIONS .)

Dihydroergotamine mesylate should not be used with peripheral and central vasoconstrictors because the combination may result in additive or synergistic elevation of blood pressure.

DRUG ABUSE AND DEPENDENCE

Currently available data have not demonstrated drug abuse or psychological dependence with dihydroergotamine. However, cases of drug abuse and psychological dependence in patients on other forms of ergot therapy have been reported. Thus, due to the chronicity of vascular headaches, it is imperative that patients be advised not to exceed recommended dosages.