ZOMIG — zolmitriptan tablet
Dispensing Solutions, Inc.
ZOMIG® (zolmitriptan) Tablets and ZOMIG-ZMT® (zolmitriptan) Orally Disintegrating Tablets contain zolmitriptan, which is a selective 5-hydroxytryptamine 1B/1D (5-HT1B/1D ) receptor agonist. Zolmitriptan is chemically designated as (S)-4-[[3-[2-(dimethylamino)ethyl]-1H-indol-5-yl]methyl]-2-oxazolidinone and has the following chemical structure:
The empirical formula is C16 H21 N3 O2 , representing a molecular weight of 287.36. Zolmitriptan is a white to almost white powder that is readily soluble in water. ZOMIG Tablets are available as 2.5 mg (yellow) and 5 mg (pink) film coated tablets for oral administration. The film coated tablets contain anhydrous lactose NF, microcrystalline cellulose NF, sodium starch glycolate NF, magnesium stearate NF, hydroxypropyl methylcellulose USP, titanium dioxide USP, polyethylene glycol 400 NF, yellow iron oxide NF (2.5 mg tablet), red iron oxide NF (5 mg tablet), and polyethylene glycol 8000 NF.
ZOMIG-ZMT® Orally Disintegrating Tablets are available as 2.5 mg and 5.0 mg white uncoated tablets for oral administration. The orally disintegrating tablets contain mannitol USP, microcrystalline cellulose NF, crospovidone NF, aspartame NF, sodium bicarbonate USP, citric acid anhydrous USP, colloidal silicon dioxide NF, magnesium stearate NF and orange flavor SN 027512.
Zolmitriptan binds with high affinity to human recombinant 5-HT1D and 5-HT1B receptors. Zolmitriptan exhibits modest affinity for 5-HT1A receptors, but has no significant affinity (as measured by radioligand binding assays) or pharmacological activity at 5-HT2 , 5-HT3 , 5-HT4 , alpha1- , alpha2- , or beta1- adrenergic; H1 , H2 , histaminic; muscarinic; dopamine1 , or dopamine2 receptors. The N-desmethyl metabolite also has high affinity for 5-HT1B/1D and modest affinity for 5-HT1A receptors.
Current theories proposed to explain the etiology of migraine headache suggest that symptoms are due to local cranial vasodilatation and/or to the release of sensory neuropeptides (vasoactive intestinal peptide, substance P and calcitonin gene-related peptide) through nerve endings in the trigeminal system. The therapeutic activity of zolmitriptan for the treatment of migraine headache can most likely be attributed to the agonist effects at the 5-HT1B/1D receptors on intracranial blood vessels (including the arterio-venous anastomoses) and sensory nerves of the trigeminal system which result in cranial vessel constriction and inhibition of pro-inflammatory neuropeptide release.
Zolmitriptan is well absorbed after oral administration for both the conventional tablets and the orally disintegrating tablets. Zolmitriptan displays linear kinetics over the dose range of 2.5 to 50 mg.
The AUC and Cmax of zolmitriptan are similar following administration of ZOMIG Tablets and ZOMIG-ZMT Orally Disintegrating Tablets, but the Tmax is somewhat later with ZOMIG-ZMT, with a median Tmax of 3 hours for the orally disintegrating tablet compared with 1.5 hours for the conventional tablet. The AUC, Cmax , and Tmax for the active N-desmethyl metabolite are similar for the two formulations.
During a moderate to severe migraine attack, mean AUC0-4 and Cmax for zolmitriptan, dosed as a conventional tablet, were decreased by 40% and 25%, respectively, and mean Tmax was delayed by one-half hour compared to the same patients during a migraine free period.
Food has no significant effect on the bioavailability of zolmitriptan. No accumulation occurred on multiple dosing.
Mean absolute bioavailability is approximately 40%. The mean apparent volume of distribution is 7.0 L/kg. Plasma protein binding of zolmitriptan is 25% over the concentration range of 10- 1000ng/mL.
Zolmitriptan is converted to an active N-desmethyl metabolite such that the metabolite concentrations are about two-thirds that of zolmitriptan. Because the 5HT1B/1D potency of the metabolite is 2 to 6 times that of the parent, the metabolite may contribute a substantial portion of the overall effect after zolmitriptan administration.
Total radioactivity recovered in urine and feces was 65% and 30% of the administered dose, respectively. About 8% of the dose was recovered in the urine as unchanged zolmitriptan. Indole acetic acid metabolite accounted for 31% of the dose, followed by N-oxide (7%) and N-desmethyl (4%) metabolites. The indole acetic acid and N-oxide metabolites are inactive.
Mean total plasma clearance is 31.5mL/min/kg, of which one-sixth is renal clearance. The renal clearance is greater than the glomerular filtration rate suggesting renal tubular secretion.
Age: Zolmitriptan pharmacokinetics in healthy elderly non-migraineur volunteers (age 65−76 yrs) were similar to those in younger non-migraineur volunteers (age 18 — 39 yrs).
Gender: Mean plasma concentrations of zolmitriptan were up to 1.5-fold higher in females than males.
Renal Impairment: Clearance of zolmitriptan was reduced by 25% in patients with severe renal impairment (Clcr ≥ 5 ≤ 25 mL/min) compared to the normal group (Clcr > = 70 mL/min); no significant change in clearance was observed in the moderately renally impaired group (Clcr ≥ 26 ≤ 50 mL/min).
Hepatic Impairment: In severely hepatically impaired patients, the mean Cmax , Tmax , and AUC0-∞ of zolmitriptan were increased 1.5, 2 (2 vs 4 hr), and 3-fold, respectively, compared to normals. Seven out of 27 patients experienced 20 to 80 mm Hg elevations in systolic and/or diastolic blood pressure after a 10 mg dose. Zolmitriptan should be administered with caution in subjects with liver disease, generally using doses less than 2.5 mg (see WARNINGS and PRECAUTIONS).
Hypertensive Patients: No differences in the pharmacokinetics of zolmitriptan or its effects on blood pressure were seen in mild to moderate hypertensive volunteers compared to normotensive controls.
Race:: Retrospective analysis of pharmacokinetic data between Japanese and Caucasians revealed no significant differences.
All drug interaction studies were performed in healthy volunteers using a single 10 mg dose of zolmitriptan and a single dose of the other drug except where otherwise noted.
Fluoxetine: The pharmacokinetics of zolmitriptan, as well as its effect on blood pressure, were unaffected by 4 weeks of pretreatment with oral fluoxetine (20 mg/day).
MAO Inhibitors: Following one week of administration of 150 mg bid moclobemide, a specific MAO-A inhibitor, there was an increase of about 25% in both Cmax and AUC for zolmitriptan and a 3-fold increase in the Cmax and AUC of the active N-desmethyl metabolite of zolmitriptan (see CONTRAINDICATIONS and PRECAUTIONS).
Selegiline, a selective MAO-B inhibitor, at a dose of 10 mg/day for 1 week, had no effect on the pharmacokinetics of zolmitriptan and its metabolite.
Propranolol: Cmax and AUC of zolmitriptan increased 1.5-fold after one week of dosing with propranolol (160 mg/day). Cmax and AUC of the N-desmethyl metabolite were reduced by 30% and 15%, respectively. There were no interactive effects on blood pressure or pulse rate following administration of propranolol with zolmitriptan.
Acetaminophen: A single 1 g dose of acetaminophen does not alter the pharmacokinetics of zolmitriptan and its N-desmethyl metabolite. However, zolmitriptan delayed the Tmax of acetaminophen by one hour.
Metoclopramide: A single 10 mg dose of metoclopramide had no effect on the pharmacokinetics of zolmitriptan or its metabolites.
Oral Contraceptives: Retrospective analysis of pharmacokinetic data across studies indicated that mean plasma concentrations of zolmitriptan were generally higher in females taking oral contraceptives compared to those not taking oral contraceptives. Mean Cmax and AUC of zolmitriptan were found to be higher by 30% and 50%, respectively, and Tmax was delayed by one-half hour in females taking oral contraceptives. The effect of zolmitriptan on the pharmacokinetics of oral contraceptives has not been studied.
Cimetidine: Following the administration of cimetidine, the half-life and AUC of a 5 mg dose of zolmitriptan and its active metabolite were approximately doubled (see PRECAUTIONS).
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