Alsuma

Dosage Forms And Strengths

ALSUMA contains 6 mg of sumatriptan (as 8.4 mg sumatriptan succinate), which is delivered as a subcutaneous injection in a single dose.

ALSUMA is supplied as a single-use auto-injector pre-filled with sumatriptan succinate drug solution and fully-assembled for use.

Storage And Handling

ALSUMA contains sumatriptan (base) as the succinate salt and is supplied as a clear, colorless to pale yellow, sterile, nonpyrogenic solution in a single-dose pre-filled auto-injector.

Store at 25°C, excursions permitted 15° to 30°C (59° to 86° F). Protect from light. Do not refrigerate.

Manufactured by: Meridian Medical Technologies, Inc., Columbia, MD 21046. A Pfizer Inc. company Distributed by: Pfizer Labs Division of Pfizer Inc. NY, NY 10017. Revised: Apr 2014

ALSUMA™ (sumatriptan injection) is indicated in adults for the acute treatment of migraine, with or without aura, and the acute treatment of cluster headache.

Limitations of Use

• Use only if a clear diagnosis of migraine or cluster headache has been established. If a patient has no response to the first migraine attack treated with ALSUMA, reconsider the diagnosis of migraine before ALSUMA is administrated to treat any subsequent attacks.
• ALSUMA is not indicated for the prevention of migraine attacks.

Dosing Information

The maximum single recommended dose of ALSUMA is 6 mg injected subcutaneously.

The maximum recommended dose that may be given in 24 hours is two doses of ALSUMA separated by at least 1 hour. Controlled clinical trials have failed to show a clear benefit with the administration of a second 6 mg dose in patients who have failed to respond to a first dose. A second 6 mg dose should only be considered if some response to a first injection was observed.

Administration Using ALSUMA

ALSUMA is only for subcutaneous use. Intramuscular or intravascular delivery must be avoided. Patients should be directed to use injection sites with an adequate skin and subcutaneous thickness to accommodate the length of the needle.

ALSUMA is for single use only. Visually inspect the medication for particulate matter and discoloration before administration. Do not use if particulates and discolorations are noted. Discard unused portions.

ALSUMA is contraindicated in patients with:

• Ischemic coronary artery disease (CAD) (angina pectoris, history of myocardial infarction, or documented silent ischemia) or coronary artery vasospasm, including Prinzmetal's angina.
• Wolff-Parkinson-White syndrome or arrhythmias associated with other cardiac accessory conduction pathway disorders.
• History of stroke or transient ischemic attack (TIA), or history or current evidence of hemiplegic or basilar migraine because these patients are at a higher risk of stroke.
• Peripheral vascular disease.
• Ischemic bowel disease..
• Uncontrolled hypertension.
• Recent (i.e., within 24 hours) use of ergotamine-containing medication, ergot-type medication (such as dihydroergotamine or methysergide), or another 5-hydroxytryptamine1 (5-HT1) agonist.
• Concurrent administration of an MAO-A inhibitor or recent (within 2 weeks) use of an MAO-A inhibitor.
• Hypersensitivity to ALSUMA (angioedema and anaphylaxis seen).
• Severe hepatic impairment.

WARNINGS

Included as part of the PRECAUTIONS section.

PRECAUTIONS

Myocardial Ischemia, Myocardial Infarction, And Prinzmetal's Angina

ALSUMA is contraindicated in patients with ischemic or vasospastic CAD. There have been rare reports of serious cardiac adverse reactions, including acute myocardial infarction, occurring within a few hours following administration of sumatriptan. Some of these reactions occurred in patients without known CAD. ALSUMA may cause coronary artery vasospasm (Prinzmetal's angina), even in patients without a history of CAD.

Perform a cardiovascular evaluation in triptan-naive patients who have multiple cardiovascular risk factors (e.g., increased age, diabetes, hypertension, smoking, obesity, strong family history of CAD) prior to receiving ALSUMA. If there is evidence of CAD or coronary artery vasospasm, ALSUMA is contraindicated. For patients with multiple cardiovascular risk factors who have a negative cardiovascular evaluation, consider administering the first dose of ALSUMA in a medically supervised setting and performing an electrocardiogram (ECG) immediately following ALSUMA. For such patients, consider periodic cardiovascular evaluation in intermittent long-term users of ALSUMA.

Arrhythmias

Life-threatening disturbances of cardiac rhythm, including ventricular tachycardia and ventricular fibrillation leading to death, have been reported within a few hours following the administration of 5-HT1 agonists. Discontinue ALSUMA if these disturbances occur. ALSUMA is contraindicated in patients with WolffParkinson-White syndrome or arrhythmias associated with other cardiac accessory conduction pathway disorders.

Chest, Throat, Neck And/Or Jaw Pain/Tightness/Pressure

Sensations of tightness, pain, pressure, and heaviness in the precordium, throat, neck, and jaw commonly occur after treatment with ALSUMA and are usually non-cardiac in origin. However, perform a cardiac evaluation if these patients are at high cardiac risk. The use of ALSUMA is contraindicated in patients shown to have CAD and those with Prinzmetal's variant angina.

Cerebrovascular Events

Cerebral hemorrhage, subarachnoid hemorrhage, and stroke have occurred in patients treated with 5-HT1 agonists, and some have resulted in fatalities. In a number of cases, it appears possible that the cerebrovascular events were primary, the 5-HT1 agonists having been administered in the incorrect belief that the symptoms experienced were a consequence of migraine when they were not. Also, patients with migraine may be at increased risk of certain cerebrovascular events (e.g., stroke, hemorrhage, TIA). Discontinue ALSUMA if a cerebrovascular event occurs.

Before treating headaches in patients not previously diagnosed as migraineurs, and in migraineurs who present with atypical symptoms, exclude other potentially serious neurological conditions. ALSUMA is contraindicated in patients with a history of stroke or TIA.

Other Vasospasm Reactions

ALSUMA may cause non-coronary vasospastic reactions, such as peripheral vascular ischemia, gastrointestinal vascular ischemia and infarction (presenting with abdominal pain and bloody diarrhea), splenic infarction, and Raynaud's syndrome. In patients who experience symptoms or signs suggestive of non-coronary vasospasm reaction following the use of any 5-HT1 agonist, rule out a vasospastic reaction before receiving additional ALSUMA doses.

Reports of transient and permanent blindness and significant partial vision loss have been reported with the use of 5-HT1 agonists. Since visual disorders may be part of a migraine attack, a causal relationship between these events and the use of 5-HT1 agonists have not been clearly established.

Medication Overuse Headache

Overuse of acute migraine drugs (e.g., ergotamine, triptans, opioids, or combination of these drugs for 10 or more days per month) may lead to exacerbation of headache (medication overuse headache). Medication overuse headache may present as migraine-like daily headaches or as a marked increase in frequency of migraine attacks. Detoxification of patients, including withdrawal of the overused drugs and treatment of withdrawal symptoms (which often includes a transient worsening of headache) may be necessary.

Serotonin Syndrome

Serotonin syndrome may occur with ALSUMA, particularly during co-administration with selective serotonin reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), and MAO inhibitors. Serotonin syndrome symptoms may include mental status changes (e.g., agitation, hallucinations, coma), autonomic instability (e.g., tachycardia, labile blood pressure, hyperthermia), neuromuscular aberrations (e.g., hyperreflexia, incoordination), and/or gastrointestinal symptoms (e.g., nausea, vomiting, diarrhea). The onset of symptoms usually occurs within minutes to hours of receiving a new or a greater dose of a serotonergic medication. Discontinue ALSUMA if serotonin syndrome is suspected.

Increase In Blood Pressure

Significant elevation in blood pressure, including hypertensive crisis with acute impairment of organ systems, has been reported on rare occasions in patients treated with 5-HT1 agonists, including patients without a history of hypertension. Monitor blood pressure in patients treated with ALSUMA. ALSUMA is contraindicated in patients with uncontrolled hypertension.

Anaphylactic/Anaphylactoid Reactions

There have been reports of anaphylactic, anaphylactoid, and hypersensitivity reactions including angioedema in patients receiving ALSUMA. Such reactions can be life threatening or fatal. In general, anaphylactic reactions to drugs are more likely to occur in individuals with a history of sensitivity to multiple allergens. ALSUMA is contraindicated in patients with a history of hypersensitivity reaction to ALSUMA.

Seizures

Seizures have been reported following administration of ALSUMA. Some have occurred in patients with either a history of seizures or concurrent conditions predisposing to seizures. There are also reports in patients where no such predisposing factors are apparent. ALSUMA should be used with caution in patients with a history of epilepsy or conditions associated with a lowered seizure threshold.

Patient Counseling Information

See FDA-approved patient labeling (PATIENT INFORMATION and Instructions for Use).

Risk of Myocardial Ischemia and/or Infarction, Prinzmetal's Angina, Other Vasospasm-Related Events, Arrhythmias, and Cerebrovascular Events

Inform patients that ALSUMA may cause serious cardiovascular side effects such as myocardial infarction or stroke. Although serious cardiovascular events can occur without warning symptoms, patients should be alert for the signs and symptoms of chest pain, shortness of breath, irregular heartbeat, significant rise in blood pressure, weakness, and slurring of speech and should ask for medical advice when observing any indicative sign or symptoms. Patients should be apprised of the importance of this follow-up.

Anaphylactic/Anaphylactoid Reactions

Inform patients that anaphylactic/anaphylactoid reactions have occurred in patients receiving sumatriptan injection. Such reactions can be life threatening or fatal. In general, anaphylactic reactions to drugs are more likely to occur in individuals with a history of sensitivity to multiple allergens.

Serotonin Syndrome

Patients should be cautioned about the risk of serotonin syndrome with the use of ALSUMA or other triptans, particularly during combined use with SSRIs, SNRIs, TCAs, and MAO inhibitors.

Medication Overuse Headache

Inform patients that use of acute migraine drugs for 10 or more days per month may lead to an exacerbation of headache and encourage patients to record headache frequency and drug use (e.g., by keeping a headache diary).

Pregnancy

Inform patients that ALSUMA should not be used during pregnancy unless the potential benefit justifies the potential risk to the fetus.

Nursing Mothers

Advise patients to notify their healthcare provider if they are breastfeeding or plan to breastfeed.

Ability to Perform Complex Tasks

Since migraines or treatment with ALSUMA may cause somnolence and dizziness, instruct patients to evaluate their ability to perform complex tasks during migraine attacks and after administration of ALSUMA.

How to Use ALSUMA

ALSUMA is a pre-filled, fully-assembled, single-use device intended to deliver a 6 mg dose of sumatriptan.

Provide patients instruction on the proper use of ALSUMA if they are able to self-administer ALSUMA in a medically unsupervised situation.

Inform patients that the injection is only intended to be given subcutaneously. Intramuscular or intravascular delivery should be avoided. Instruct patients to use injection sites with an adequate skin and subcutaneous thickness to accommodate the length of the needle (e.g. lateral thigh or upper arms).

Nonclinical Toxicology

Carcinogenesis, Mutagenesis, Impairment Of Fertility

Carcinogenesis

In carcinogenicity studies in mouse and rat, sumatriptan was administered orally for 78 and 104 weeks, respectively, at doses up to 160 mg/kg/day (the high dose in rat was reduced from 360 mg/kg/day during week 21). There was no evidence in either species of an increase in tumors related to sumatriptan administration.

Mutagenesis

Sumatriptan was negative in in vitro (bacterial reverse mutation [Ames], gene cell mutation in Chinese hamster V79/HGPRT, chromosomal aberration in human lymphocytes) assay and in vivo (rat micronucleus) assays.

Impairment of Fertility

When sumatriptan (5, 50, 500 mg/kg/day) was administered orally to male and female rats prior to and throughout the mating period, there was a treatment-related decrease in fertility secondary to a decrease in mating in animals treated with doses greater than 5 mg/kg/day. It is not clear whether this finding was due to an effect on males or females or both.

Use In Specific Populations

Pregnancy

Pregnancy Category C

There are no adequate and well-controlled trials of sumatriptan injection in pregnant women. In developmental toxicity studies in rats and rabbits, oral administration of sumatriptan to pregnant animals was associated with embryolethality, fetal abnormalities, and pup mortality. When administered by the intravenous route to pregnant rabbits, sumatriptan was embryolethal. ALSUMA should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Oral administration of sumatriptan to pregnant rats during the period of organogenesis resulted in an increased incidence of fetal blood vessel (cervicothoracic and umbilical) abnormalities. The highest no-effect dose for embryofetal developmental toxicity in rats was 60 mg/kg/day. Oral administration of sumatriptan to pregnant rabbits during the period of organogenesis resulted in increased incidences of embryolethality and fetal cervicothoracic vascular and skeletal abnormalities. Intravenous administration of sumatriptan to pregnant rabbits during the period of organogenesis resulted in an increased incidence of embryolethality. The highest oral and intravenous no-effect doses for developmental toxicity in rabbits were 15 and 0.75 mg/kg/day, respectively.

Oral administration of sumatriptan to rats prior to and throughout gestation resulted in embryofetal toxicity (decreased body weight, decreased ossification, increased incidence of skeletal abnormalities). The highest no-effect dose was 50 mg/kg/day. In offspring of pregnant rats treated orally with sumatriptan during organogenesis, there was a decrease in pup survival. The highest no-effect dose for this effect was 60 mg/kg/day. Oral treatment of pregnant rats with sumatriptan during the latter part of gestation and throughout lactation resulted in a decrease in pup survival. The highest no-effect dose for this effect was 100 mg/kg/day.

Nursing Mothers

Sumatriptan is excreted in human milk following subcutaneous administration. Infant exposure to sumatriptan can be minimized by avoiding breastfeeding for 12 hours after treatment with ALSUMA.

Pediatric Use

Safety and effectiveness in pediatric patients have not been established. ALSUMA is not recommended for use in patients younger than 18 years of age.

Two controlled clinical trials evaluated sumatriptan nasal spray (5 to 20 mg) in 1,248 adolescent migraineurs aged 12 to 17 years who treated a single attack. The trials did not establish the efficacy of sumatriptan nasal spray compared with placebo in the treatment of migraine in adolescents. Adverse reactions observed in these clinical trials were similar in nature to those reported in clinical trials in adults.

Five controlled clinical trials (2 single-attack trials, 3 multiple-attack trials) evaluating oral sumatriptan (25 to 100 mg) in pediatric subjects aged 12 to 17 years enrolled a total of 701 adolescent migraineurs. These trials did not establish the efficacy of oral sumatriptan compared with placebo in the treatment of migraine in adolescents. Adverse reactions observed in these clinical trials were similar in nature to those reported in clinical trials in adults. The frequency of all adverse reactions in these subjects appeared to be both dose-and age-dependent, with younger subjects reporting reactions more commonly than older adolescents.

Postmarketing experience documents that serious adverse reactions have occurred in the pediatric population after use of subcutaneous, oral, and/or intranasal sumatriptan. These reports include reactions similar in nature to those reported rarely in adults, including stroke, visual loss, and death. A myocardial infarction has been reported in a 14-year-old male following the use of oral sumatriptan; clinical signs occurred within 1 day of drug administration. Clinical data to determine the frequency of serious adverse reactions in pediatric patients who might receive subcutaneous, oral, or intranasal sumatriptan are not presently available.

Geriatric Use

Clinical trials of sumatriptan injection did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger subjects. In general, dose selection for an elderly patient should be cautious, usually starting at the low end of the dosing range, reflecting the greater frequency of decreased hepatic, renal, or cardiac function and of concomitant disease or other drug therapy.

A cardiovascular evaluation is recommended for geriatric patients who have other cardiovascular risk factors (e.g., diabetes, hypertension, smoking, obesity, strong family history of CAD) prior to receiving ALSUMA.

SIDE EFFECTS

The following adverse reactions are discussed in more detail in other sections of the prescribing information:

• Myocardial ischemia, myocardial infarction, and Prinzmetal's angina
• Arrhythmias
• Chest, throat, neck, and/or jaw pain/tightness/pressure
• Cerebrovascular events
• Other vasospasm reactions
• Medication overuse headache
• Serotonin syndrome
• Increase in blood pressure
• Hypersensitivity reactions
• Seizures

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Migraine Headache

Table 1 lists adverse reactions that occurred in 2 US placebo-controlled clinical trials in migraine subjects [Studies 2 and 3, see Clinical Studies] following either a single 6-mg dose of sumatriptan injection or placebo. Only reactions that occurred at a frequency of 2% or more in groups treated with sumatriptan injection 6 mg and that occurred at a frequency greater than the placebo group are included in Table 1.

Table 1: Adverse Reactions Reported by at Least 2% of Subjects and at a Greater Frequency Than Placebo in 2 Placebo-Controlled Migraine Clinical Trials (Studies 2 and 3)^a

The incidence of adverse reactions in controlled clinical trials was not affected by gender or age of the subjects. There were insufficient data to assess the impact of race on the incidence of adverse reactions.

Cluster Headache

In the controlled clinical trials assessing the efficacy of sumatriptan injection as a treatment for cluster headache [Studies 4 and 5, see Clinical Studies], no new significant adverse reactions were detected that had not already been identified in trials of sumatriptan in subjects with migraine.

Overall, the frequency of adverse reactions reported in the trials of cluster headache was generally lower than in the migraine trials. Exceptions include reports of paresthesia (5% sumatriptan, 0% placebo), nausea and vomiting (4% sumatriptan, 0% placebo), and bronchospasm (1% sumatriptan, 0% placebo).

Adverse Reactions Observed In Association With The Administration of ALSUMA

The safety of ALSUMA was evaluated in an open-label clinical trial evaluating the usability of ALSUMA during a migraine attack. Adverse reactions that occurred at a frequency of 5% or higher were injection site bruising (16%), injection site pain (6%), and injection site hemorrhage (6%).

DRUG INTERACTIONS

Ergot-Containing Drugs

Ergot-containing drugs have been reported to cause prolonged vasospastic reactions. Because these effects may be additive, use of ergotamine-containing or ergot-type medications (like dihydroergotamine or methysergide) and ALSUMA within 24 hours of each other is contraindicated.

Monoamine Oxidase-A Inhibitors

MAO-A inhibitors increase systemic exposure by 2-fold. Therefore, the use of ALSUMA in patients receiving MAO-A inhibitors is contraindicated.

Other 5-HT1 Agonists

Because their vasospastic effects may be additive, co-administration of ALSUMA and other 5-HT1 agonists (e.g., triptans) within 24 hours of each other is contraindicated.

Selective Serotonin Reuptake Inhibitors/Serotonin Norepinephrine Reuptake Inhibitors And Serotonin Syndrome

Cases of serotonin syndrome have been reported during co-administration of triptans and SSRIs, or SNRIs, SNRIs, TCAs, and MAO inhibitors.

Pregnancy Category C

There are no adequate and well-controlled trials of sumatriptan injection in pregnant women. In developmental toxicity studies in rats and rabbits, oral administration of sumatriptan to pregnant animals was associated with embryolethality, fetal abnormalities, and pup mortality. When administered by the intravenous route to pregnant rabbits, sumatriptan was embryolethal. ALSUMA should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Oral administration of sumatriptan to pregnant rats during the period of organogenesis resulted in an increased incidence of fetal blood vessel (cervicothoracic and umbilical) abnormalities. The highest no-effect dose for embryofetal developmental toxicity in rats was 60 mg/kg/day. Oral administration of sumatriptan to pregnant rabbits during the period of organogenesis resulted in increased incidences of embryolethality and fetal cervicothoracic vascular and skeletal abnormalities. Intravenous administration of sumatriptan to pregnant rabbits during the period of organogenesis resulted in an increased incidence of embryolethality. The highest oral and intravenous no-effect doses for developmental toxicity in rabbits were 15 and 0.75 mg/kg/day, respectively.

Oral administration of sumatriptan to rats prior to and throughout gestation resulted in embryofetal toxicity (decreased body weight, decreased ossification, increased incidence of skeletal abnormalities). The highest no-effect dose was 50 mg/kg/day. In offspring of pregnant rats treated orally with sumatriptan during organogenesis, there was a decrease in pup survival. The highest no-effect dose for this effect was 60 mg/kg/day. Oral treatment of pregnant rats with sumatriptan during the latter part of gestation and throughout lactation resulted in a decrease in pup survival. The highest no-effect dose for this effect was 100 mg/kg/day.

The following adverse reactions are discussed in more detail in other sections of the prescribing information:

• Myocardial ischemia, myocardial infarction, and Prinzmetal's angina
• Arrhythmias
• Chest, throat, neck, and/or jaw pain/tightness/pressure
• Cerebrovascular events
• Other vasospasm reactions
• Medication overuse headache
• Serotonin syndrome
• Increase in blood pressure
• Hypersensitivity reactions
• Seizures

Clinical Trials Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared with rates in the clinical trials of another drug and may not reflect the rates observed in practice.

Migraine Headache

Table 1 lists adverse reactions that occurred in 2 US placebo-controlled clinical trials in migraine subjects [Studies 2 and 3, see Clinical Studies] following either a single 6-mg dose of sumatriptan injection or placebo. Only reactions that occurred at a frequency of 2% or more in groups treated with sumatriptan injection 6 mg and that occurred at a frequency greater than the placebo group are included in Table 1.

Table 1: Adverse Reactions Reported by at Least 2% of Subjects and at a Greater Frequency Than Placebo in 2 Placebo-Controlled Migraine Clinical Trials (Studies 2 and 3)^a

The incidence of adverse reactions in controlled clinical trials was not affected by gender or age of the subjects. There were insufficient data to assess the impact of race on the incidence of adverse reactions.

Cluster Headache

In the controlled clinical trials assessing the efficacy of sumatriptan injection as a treatment for cluster headache [Studies 4 and 5, see Clinical Studies], no new significant adverse reactions were detected that had not already been identified in trials of sumatriptan in subjects with migraine.

Overall, the frequency of adverse reactions reported in the trials of cluster headache was generally lower than in the migraine trials. Exceptions include reports of paresthesia (5% sumatriptan, 0% placebo), nausea and vomiting (4% sumatriptan, 0% placebo), and bronchospasm (1% sumatriptan, 0% placebo).

Adverse Reactions Observed In Association With The Administration of ALSUMA

The safety of ALSUMA was evaluated in an open-label clinical trial evaluating the usability of ALSUMA during a migraine attack. Adverse reactions that occurred at a frequency of 5% or higher were injection site bruising (16%), injection site pain (6%), and injection site hemorrhage (6%).

Data on overdose of Alsuma and its treatment are lacking in humans. Overdoses would be expected from animal data (dogs at 0.1 g/kg, rats at 2 g/kg) to possibly cause convulsions, tremor, inactivity, erythema of the extremities, reduced respiratory rate, cyanosis, ataxia, mydriasis, injection site reactions (desquamation, hair loss, and scab formation), and paralysis.

The elimination half-life of sumatriptan is about 2 hours , and therefore monitoring of patients after overdose with subcutaneous sumatriptan should continue for at least 10 hours or while symptoms or signs persist.

It is unknown what effect hemodialysis or peritoneal dialysis has on the serum concentrations of sumatriptan.

Blood Pressure

Significant elevation in blood pressure, including hypertensive crisis, has been reported in patients with and without a history of hypertension.

Peripheral (Small) Arteries

In healthy volunteers (N = 18), a trial evaluating the effects of sumatriptan on peripheral (small vessel) arterial reactivity failed to detect a clinically significant increase in peripheral resistance.

Heart Rate

Transient increases in blood pressure observed in some subjects in clinical trials carried out during sumatriptan's development as a treatment for migraine were not accompanied by any clinically significant changes in heart rate.

Absorption and Bioavailability

The bioavailability of sumatriptan via subcutaneous site injection to 18 healthy male subjects was 97% ± 16% of that obtained following intravenous injection.

After a single 6-mg subcutaneous manual injection into the deltoid area of the arm in 18 healthy males (age: 24 ± 6 years, weight: 70 kg), the maximum serum concentration (Cmax) of sumatriptan was (mean ± standard deviation) 74 ± 15 ng/mL and the time to peak concentration (Tmax) was 12 minutes after injection (range: 5 to 20 minutes). In this trial, the same dose injected subcutaneously in the thigh gave a Cmax of 61 ± 15 ng/mL by manual injection versus 52 ± 15 ng/mL by autoinjector techniques. The Tmax or amount absorbed was not significantly altered by either the site or technique of injection.

Distribution

Protein binding, determined by equilibrium dialysis over the concentration range of 10 to 1,000 ng/mL, is low, approximately 14% to 21%. The effect of sumatriptan on the protein binding of other drugs has not been evaluated.

Following a 6-mg subcutaneous injection into the deltoid area of the arm in 9 males (mean age: 33 years, mean weight: 77 kg) the volume of distribution central compartment of sumatriptan was 50 ± 8 liters and the distribution half-life was 15 ± 2 minutes.

Metabolism

In vitro studies with human microsomes suggest that sumatriptan is metabolized by MAO, predominantly the A isoenzyme. Most of a radiolabeled dose of sumatriptan excreted in the urine is the major metabolite indole acetic acid (IAA) or the IAA glucuronide, both of which are inactive.

Elimination

After a single 6-mg subcutaneous dose, 22% ± 4% was excreted in the urine as unchanged sumatriptan and 38% ± 7% as the IAA metabolite.

Following a 6-mg subcutaneous injection into the deltoid area of the arm, the systemic clearance of sumatriptan was 1,194 ± 149 mL/min and the terminal half-life was 115 ± 19 minutes.