Naratriptan (as Naratriptan Hydrochloride) 2.5 Mg Oral Tablet

If the migraine returns or if the patient has only partial response, the dose may be repeated once after 4 hours, for a maximum dose of 5 mg in a 24-hour period.

The safety of treating an average of more than 4 migraine attacks in a 30-day period has not been established.

In patients with mild to moderate renal impairment, the maximum daily dose should not exceed 2.5 mg over a 24-hour period and a 1-mg starting dose is recommended [see Use in Specific Populations (8.6) , Clinical Pharmacology (12.3) ].

In patients with mild or moderate hepatic impairment (Child-Pugh Grade A or B), the maximum daily dose should not exceed 2.5 mg over a 24-hour period and a 1-mg starting dose is recommended [see Use in Specific Populations (8.7) , Clinical Pharmacology (12.3) ].

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 naratriptan. If there is evidence of CAD or coronary artery vasospasm, naratriptan is contraindicated. For patients with multiple cardiovascular risk factors who have a negative cardiovascular evaluation, consider administering the first dose of naratriptan in a medically supervised setting and performing an electrocardiogram (ECG) immediately following administration of naratriptan. For such patients, consider periodic cardiovascular evaluation in intermittent long-term users of naratriptan.

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

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.

There are no adequate data on the developmental risk associated with use of naratriptan in pregnant women. Data from a prospective pregnancy exposure registry and epidemiological studies of pregnant women have documented outcomes in women exposed to naratriptan during pregnancy; however, due to small sample sizes, no definitive conclusions can be drawn regarding the risk of birth defects following exposure to naratriptan [ see Data ]. In animal studies, naratriptan produced developmental toxicity (including embryolethality and fetal abnormalities) when administered to pregnant rats and rabbits. The lowest doses producing evidence of developmental toxicity in animals were associated with plasma exposures 2.5 (rabbit) to 11 (rat) times that in humans at the maximum recommended daily dose (MRDD) [ see Data ].

In the U.S. general population, the estimated background risk of major birth defects and of miscarriage in clinically recognized pregnancies is 2% to 4% and 15% to 20%, respectively. The reported rate of major birth defects among deliveries to women with migraine ranged from 2.2% to 2.9% and of miscarriage was 17%, which were similar to rates reported in women without migraine.

Clinical Considerations

Disease-Associated Maternal and/or Embryo/Fetal Risk

Several studies have suggested that women with migraine may be at increased risk of preeclampsia during pregnancy.

Data

Human Data : The numbers of exposed pregnancy outcomes accumulated during the Sumatriptan/Naratriptan/ Treximet®  (sumatriptan  and naproxen sodium) Pregnancy Registry, a population-based international prospective study that collected data from October 1997 to September 2012, and smaller observational studies, were insufficient to define a level of risk for naratriptan in pregnant women. The Registry documented outcomes of 57 infants and fetuses exposed to naratriptan during pregnancy (52 exposed during the first trimester and 5 exposed during the second trimester). The occurrence of major birth defects (excluding fetal deaths and induced abortions without reported defects and all spontaneous pregnancy losses) during  first-trimester exposure to naratriptan was 2.2% (1/46 [95% CI: 0.1% to 13.0%]) and during any trimester of exposure was 2.0% (1/51[95% CI: 0.1% to 11.8%]). Seven infants were exposed to both naratriptan and sumatriptan in utero, and one of these  infants with first-trimester exposure was born with a major birth defect (ventricular septal defect). The sample size in this study had 80% power to detect at least a 3.8- to 4.6- fold increase in the rate of major malformations.

In a study using data from the Swedish Medical Birth Register, women who used triptans or ergots during pregnancy were compared with women who did not. Of the 22 births with first-trimester exposure to naratriptan, one infant was born with malformation (congenital deformity of the hand).

Animal Data : When naratriptan was administered to pregnant rats during the period of organogenesis at doses of 10, 60, or 340 mg/kg/day, there was a dose-related increase in embryonic death; incidences of fetal structural variations (incomplete/irregular ossification of skull bones, sternebrae, ribs) were increased at all doses. The maternal plasma exposures (AUC) at these doses were approximately 11, 70, and 470 times the exposure in humans at the MRDD. The high dose was maternally toxic, as evidenced by decreased maternal body weight gain during gestation. A no-effect dose for developmental toxicity in rats exposed during organogenesis was not established.

When naratriptan was administered orally (1, 5, or 30 mg/kg/day) to pregnant Dutch rabbits throughout organogenesis, the incidence of a specific fetal skeletal malformation (fused sternebrae) was increased at the high dose, the incidence of fetal variations (major blood vessel variations, supernumerary ribs, incomplete skeletal ossification) was increased at the mid and high doses, and embryonic death was increased at all doses (4, 20, and 120 times, respectively, the MRDD on a body surface area basis). Maternal toxicity (decreased body weight gain) was evident at the high dose. In a similar study in New Zealand White rabbits (1, 5, or 30 mg/kg/day throughout organogenesis), decreased fetal weights and increased incidences of fetal skeletal variations were observed at all doses (maternal exposures equivalent to 2.5, 19, and 140 times exposure in humans receiving the MRDD), while maternal body weight gain was reduced at 5 mg/kg or greater. A no-effect dose for developmental toxicity in rabbits exposed during organogenesis was not established.

When female rats were treated orally with naratriptan (10, 60, or 340 mg/kg/day) during late gestation and lactation, offspring behavioral impairment (tremors) and decreased offspring viability and growth were observed at doses of 60 mg/kg or greater, while maternal toxicity occurred only at the highest dose. Maternal exposures at the no-effect dose for developmental effects in this study were approximately 11 times the exposure in humans receiving the MRDD.

There are no data on the presence of naratriptan in human milk, the effects of naratriptan on the breastfed infant, or the effects of naratriptan on milk production. Naratriptan is present in rat milk.

The developmental and health benefits of breastfeeding should be considered along with the mother's clinical need for naratriptan and any potential adverse effects on the breastfed infant from naratriptan or from the underlying maternal condition.

One controlled clinical trial evaluated naratriptan tablets (0.25 to 2.5 mg) in 300 adolescent migraineurs aged 12 to 17 years who received at least 1 dose of naratriptan tablets for an acute migraine. In this study, 54% of the patients were female and 89% were Caucasian. There were no statistically significant differences between any of the treatment groups. The headache response rates at 4 hours (n) were 65% (n = 74), 67% (n = 78), and 64% (n = 70) for placebo, 1-mg, and 2.5-mg groups, respectively. This trial did not establish the efficacy of naratriptan compared with placebo in the treatment of migraine in adolescents. Adverse reactions observed in this clinical trial were similar in nature to those reported in clinical trials in adults.

Naratriptan is known to be substantially excreted by the kidney, and the risk of adverse reactions to this drug may be greater in elderly patients who have reduced renal function. In addition, elderly patients are more likely to have decreased hepatic function, they are at higher risk for CAD, and blood pressure increases may be more pronounced in the elderly.

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 naratriptan [see Warnings and Precautions (5.1) ].

In 10 subjects with suspected CAD undergoing coronary artery catheterization, there was a 1% to 10% reduction in coronary artery diameter following subcutaneous injection of 1.5 mg of naratriptan [see Contraindications (4) ].

Naratriptan displays linear kinetics over the therapeutic dose range.

Distribution: The steady-state volume of distribution of naratriptan is 170 L. Plasma protein binding is 28% to 31% over the concentration range of 50 to 1,000 ng/mL.

Metabolism: In vitro, naratriptan is metabolized by a wide range of cytochrome P450 isoenzymes into a number of inactive metabolites.

Elimination: Naratriptan is predominantly eliminated in urine, with 50% of the dose recovered unchanged and 30% as metabolites in urine. The mean elimination half-life of naratriptan is 6 hours. The systemic clearance of naratriptan is 6.6 mL/min/kg. The renal clearance (220 mL/min) exceeds glomerular filtration rate, indicating active tubular secretion. Repeat administration of naratriptan tablets does not result in drug accumulation.

Special Populations:

Age: A small decrease in clearance (approximately 26%) was observed in healthy elderly subjects (65 to 77 years) compared with younger subjects, resulting in slightly higher exposure [see Use in Specific Populations (8.5) ].

Race: The effect of race on the pharmacokinetics of naratriptan has not been examined.

Renal Impairment: Clearance of naratriptan was reduced by 50% in subjects with moderate renal impairment (creatinine clearance: 18 to 39 mL/min) compared with the normal group. Decrease in clearances resulted in an increase of mean half-life from 6 hours (healthy) to 11 hours (range: 7 to 20 hours). The mean C_max increased by approximately 40%. The effects of severe renal impairment (creatinine clearance: ≤ 15 mL/min) on the pharmacokinetics of naratriptan have not been assessed [see Contraindications (4) ].

Hepatic Impairment: Clearance of naratriptan was decreased by 30% in subjects with moderate hepatic impairment (Child-Pugh Grade A or B). This resulted in an approximately 40% increase in the half-life (range: 8 to 16 hours). The effects of severe hepatic impairment (Child-Pugh Grade C) on the pharmacokinetics of naratriptan have not been assessed [see Contraindications (4) ].

Drug Interaction Studies: From population pharmacokinetic analyses, co-administration of naratriptan and fluoxetine, beta-blockers, or tricyclic antidepressants did not affect the clearance of naratriptan.

Oral Contraceptives: Oral contraceptives reduced clearance by 32% and volume of distribution by 22%, resulting in slightly higher concentrations of naratriptan. Hormone replacement therapy had no effect on pharmacokinetics in older female patients.

Monoamine Oxidase and P450 Inhibitors: Naratriptan does not inhibit monoamine oxidase (MAO) enzymes and is a poor inhibitor of P450; metabolic interactions between naratriptan and drugs metabolized by P450 or MAO are therefore unlikely.

Smoking: Smoking increased the clearance of naratriptan by 30%.

Alcohol: In normal volunteers, co-administration of single doses of naratriptan tablets and alcohol did not result in substantial modification of naratriptan pharmacokinetic parameters.

Mutagenesis: Naratriptan was not mutagenic when tested in in vitro gene mutation (Ames and mouse lymphoma tk ) assays. Naratriptan was also negative in the in vitro human lymphocyte assay and the in vivo mouse micronucleus assay. Naratriptan can be nitrosated in vitro to form a mutagenic product (WHO nitrosation assay) that has been detected in the stomachs of rats fed a nitrite-supplemented diet.

Impairment of Fertility: In a reproductive toxicity study in which male and female rats were administered naratriptan orally prior to and throughout the mating period (10, 60, 170, or 340 mg/kg/day; plasma exposures [AUC] approximately 11, 70, 230, and 470 times, respectively, the human exposure at the MRDD), there was a drug-related decrease in the number of females exhibiting normal estrous cycles at doses of 170 mg/kg/day or greater and an increase in preimplantation loss at 60 mg/kg/day or greater. In high-dose males, testicular/epididymal atrophy accompanied by spermatozoa depletion reduced mating success and may have contributed to the observed preimplantation loss. The exposures achieved at the no-effect doses for preimplantation loss, anestrus, and testicular effects were approximately 11, 70, and 230 times, respectively, the exposures in humans at the MRDD.

In a study in which rats were dosed orally with naratriptan (10, 60, or 340 mg/kg/day) for 6 months, changes in the female reproductive tract including atrophic or cystic ovaries and anestrus were seen at the high dose. The exposure at the no-effect dose of 60 mg/kg was approximately 85 times that in humans at the MRDD.