CHCs containing EE may inhibit the metabolism of other compounds (e.g., cyclosporine, prednisolone, theophylline, tizanidine, and voriconazole) and increase their plasma concentrations. CHCs have been shown to decrease plasma concentrations of acetaminophen, clofibric acid, morphine, salicylic acid, and temazepam. Significant decrease in plasma concentration of lamotrigine has been shown, likely due to induction of lamotrigine glucuronidation. This may reduce seizure control; therefore, dosage adjustments of lamotrigine may be necessary.
Women on thyroid hormone replacement therapy may need increased doses of thyroid hormone because serum concentration of thyroid-binding globulin increases with use of CHCs [see Warnings and Precautions (5.13)].
Do not co-administer ZAFEMY with HCV drug combinations containing ombitasvir/paritaprevir/ritonavir, with or without dasabuvir, due to potential for ALT elevations [see Warnings and Precautions (5.4)].
The use of contraceptive steroids may influence the results of certain laboratory tests, such as coagulation factors, lipids, glucose tolerance, and binding proteins.
There is little or no increased risk of birth defects in women who inadvertently use hormonal contraceptives during early pregnancy. Epidemiologic studies and meta-analyses have not found an increased risk of genital or non-genital birth defects (including cardiac anomalies and limb reduction defects) following exposure to low dose hormonal contraceptives prior to conception or during early pregnancy.
The administration of hormonal contraceptives to induce withdrawal bleeding should not be used as a test for pregnancy. Hormonal contraceptives should not be used during pregnancy to treat threatened or habitual abortion.
The effects of ZAFEMY in nursing mothers have not been evaluated and are unknown. When possible, advise the nursing mother to use other forms of contraception until she has completely weaned her child. Estrogen-containing CHCs can reduce milk production in breastfeeding mothers. This is less likely to occur once breastfeeding is well-established; however, it can occur at any time in some women. Small amounts of contraceptive steroids and/or metabolites are present in breast milk.
Safety and efficacy of ZAFEMY have been established in women of reproductive age. Efficacy is expected to be the same for post-pubertal adolescents under the age of 18 and for users 18 years and older. Use of this product before menarche is not indicated.
ZAFEMY has not been studied in postmenopausal women and is not indicated in this population.
No studies with ZAFEMY have been conducted in women with hepatic impairment. However, steroid hormones may be poorly metabolized in patients with impaired liver function. Acute or chronic disturbances of liver function may necessitate the discontinuation of combined hormonal contraceptive use until markers of liver function return to normal and combined hormonal contraceptive causation has been excluded [see Contraindications (4) and Warnings and Precautions (5.3)].
No studies with ZAFEMY have been conducted in women with renal impairment.
ZAFEMY may be less effective in preventing pregnancy in women who weigh 198 lbs or more [see Clinical Studies (14)].
Overdosage may cause nausea and vomiting, and withdrawal bleeding may occur in women. In case of suspected overdose, all ZAFEMY patches should be removed and symptomatic treatment given.
ZAFEMY is a transdermal system with a contact surface area of 12.5 cm2. It contains 3.15 mg norelgestromin, USP (NGMN) and 0.289 mg ethinyl estradiol, USP (EE), and its delivery rate is approximately 150 mcg of NGMN, USP and 35 mcg of EE, USP per day. Systemic exposures (as measured by area under the curve [AUC] and steady-state concentration [Css ]) of NGMN, USP and EE, USP during use of ZAFEMY are higher and the Cmax is lower than those produced by an oral contraceptive containing norgestimate, USP (NGM) 250 mcg / EE, USP 35 mcg [see Boxed Warning and Clinical Pharmacology (12.3)].
ZAFEMY is a thin, matrix-type transdermal system consisting of three layers. The backing layer is composed of a tan backing consisting of pigmented polyethylene and polyester. It provides structural support and protects the middle adhesive layer from the environment. The middle layer contains polyisobutylene/polybutene adhesive, polybutene, crospovidone, oleyl alcohol and dipropylene glycol as inactive components. The active components in this layer are the hormones, NGMN, USP and EE, USP. The third layer is the release liner, which protects the adhesive layer during storage and is removed just prior to application. It is a transparent polyethylene terephthalate (PET) film with a silicone coating on the side that is in contact with the middle adhesive layer.
The outside of the backing layer is printed with “Norelgestromin and Ethinyl Estradiol 150/35 mcg per day” in brown ink.
The structural formulas of the components are:
Norelgestromin, USP ethinyl estradiol, USP
Molecular weight, NGMN, USP: 327.47
Molecular weight, EE, USP: 296.41
Chemical name for NGMN, USP: 18, 19-Dinorpregn-4-en-20-yn-3-one, 13-ethyl-17-hydroxy-,3-oxime,(17α)
Chemical name for EE, USP: 19-Norpregna-1,3,5(10)-trien-20-yne-3, 17-diol,(17α)
NGMN is the active progestin largely responsible for the progestational activity that occurs in women following application of ZAFEMY. NGMN is also the primary active metabolite produced following oral administration of NGM, the progestin component of some oral contraceptive products.
Combination hormonal contraceptives act by suppression of gonadotropins. Although the primary mechanism of this action is inhibition of ovulation, other alterations include changes in the cervical mucus (which increase the difficulty of sperm entry into the uterus) and the endometrium (which reduce the likelihood of implantation).
One clinical trial assessed the return of hypothalamic-pituitary-ovarian axis function post-therapy and found that follicle-stimulating hormone (FSH), luteinizing hormone (LH), and estradiol mean values, though suppressed during therapy, returned to near baseline values during the 6 weeks post therapy.
The systemic delivery rate of NGMN and EE from ZAFEMY is approximately 150 mcg of NGMN and 35 mcg of EE per day based on a comparative analysis with intravenous (IV) data. Following a single application of ZAFEMY, both NGMN and EE reach a plateau by approximately 48 hours. Pooled data from the 3 clinical studies have demonstrated that steady-state is reached within 2 weeks of application. In one of the clinical studies, Css concentrations across all subjects ranged from 0.305 to 1.53 ng/mL for NGMN and from 23 to 137 pg/mL for EE.
Absorption of NGMN and EE following application of ZAFEMY to the buttock, upper outer arm, abdomen and upper torso (excluding breast) was examined. While absorption from the abdomen was slightly lower than from other sites, absorption from these anatomic sites was considered to be therapeutically equivalent.
The mean (%CV) PK parameters Css and AUC0-168 for NGMN and EE following a single buttock application of ZAFEMY are summarized in Table 5.
In multiple dose studies, AUC0-168 for NGMN and EE was found to increase over time (Table 5). In a three-cycle study, these PK parameters reached steady-state conditions during Cycle 3 (Figures 5 and 4). Upon removal of the patch, serum levels of EE and NGMN reach very low or non-measurable levels within 3 days.
Table 5: Mean (%CV*) PK Parameters of NGMN and EE Following 3 Consecutive Cycles of ZAFEMY Wear on the Buttock
Cycle 1 Week 1
Cycle 3 Week 1
Cycle 3 Week 2
Cycle 3 Week 3
Css (ng/mL) AUC0-168 (ng·h/mL) t1/2 (h)
0.70 (39.4) 107 (44.2) nc
0.70 (41.8) 105 (43.2) nc
0.80 (28.7) 132 (43.4) nc
0.70 (45.3) 120 (43.9) 32.1 (40.3)
Css (pg/mL) AUC0-168 (pg·h/mL) t1/2 (h)
46.4 (38.5) 6,796 (39.3) nc
47.6 (36.4) 7,160 (40.4) nc
59.0 (42.5) 10,054 (41.8) nc
49.6 (54.4) 8,840 (58.6) 21.0 (43.2)
nc = not calculated, *%CV is % of Coefficient of variation = 100 (standard deviation/mean)
Figure 3: Mean Serum NGMN Concentrations (ng/mL) in Healthy Female Volunteers Following Application of ZAFEMY on the Buttock for Three Consecutive Cycles (Vertical arrow indicates time of patch removal)
Figure 4: Mean Serum EE Concentrations (pg/mL) in Healthy Female Volunteers Following Application of ZAFEMY on the Buttock for Three Consecutive Cycles (Vertical arrow indicates time of patch removal.)
The absorption of NGMN and EE following application of ZAFEMY was studied under conditions encountered in a health club (sauna, whirlpool and treadmill) and in a cold water bath.
The results indicated that for NGMN, there were no significant treatment effects on Css or AUC when compared to normal wear. For EE, increased exposures were observed due to sauna, whirlpool and treadmill. There was no significant effect of cold water on these parameters.
Results from a study of consecutive ZAFEMY wear for 7 days and 10 days indicated that serum concentrations of NGMN and EE dropped slightly during the first 6 hours after the patch replacement, and recovered within 12 hours. By Day 10 of patch administration, both NGMN and EE concentrations had decreased by approximately 25% when compared to Day 7 concentrations.
Since norelgestromin and ethinyl estradiol are delivered transdermally, first-pass metabolism (via the gastrointestinal tract and/or liver) of NGMN and EE that would be expected with oral administration does not occur. Hepatic metabolism of NGMN occurs and metabolites include norgestrel, which is highly bound to SHBG, and various hydroxylated and conjugated metabolites. EE is also metabolized to various hydroxylated products and their glucuronide and sulfate conjugates.
NGMN and norgestrel (a serum metabolite of NGMN) are highly bound (>97%) to serum proteins. NGMN is bound to albumin and not to SHBG, while norgestrel is bound primarily to SHBG, which limits its biological activity. EE is extensively bound to serum albumin and induces an increase in the serum concentrations of SHBG (see Table 5).
Following removal of patches, the elimination kinetics of NGMN and EE were consistent for all studies with half-life values of approximately 28 hours and 17 hours, respectively. The metabolites of NGMN and EE are eliminated by renal and fecal pathways.
Transdermal versus Oral Contraceptives
The ZAFEMY transdermal patch delivers EE and NGMN over a seven-day period while oral contraceptives (containing NGM 250 mcg / EE 35 mcg) are administered on a daily basis. Figures 5 and 6 present mean PK profiles for EE and NGMN following administration of an oral contraceptive (containing NGM 250 mcg / EE 35 mcg) compared to the 7-day transdermal ZAFEMY patch (containing NGMN 3.15 mg / EE 0.289 mg) during Cycle 2 in 32 healthy female volunteers.
Figure 5: Mean Serum Concentration-Time Profiles of NGMN Following Once-Daily Administration of an Oral Contraceptive for 2 Cycles or Application of ZAFEMY for 2 Cycles to the Buttock in Healthy Female Volunteers. [Oral contraceptive: Cycle 2, Days 15 to 21, ZAFEMY: Cycle 2, Week 3]
Figure 6: Mean Serum Concentration-Time Profiles of EE Following Once-Daily Administration of an Oral Contraceptive for 2 Cycles or Application of ZAFEMY for 2 Cycles to the Buttock in Healthy Female Volunteers. [Oral contraceptive: Cycle 2, Days 15 to 21, ZAFEMY: Cycle 2, Week 3]
Table 6 provides the mean (%CV) for NGMN and EE pharmacokinetic (PK) parameters.
Table 6: Mean (%CV) NGMN and EE Steady-State Pharmacokinetic Parameters Following Application of ZAFEMY and Once-Daily Administration of an Oral Contraceptive (containing NGM 250 mcg / EE 35 mcg) in Healthy Female Volunteers
* Cycle 2, Week 3
† Cycle 2, Day 21
‡ NGM is rapidly metabolized to NGMN following oral administration
§ Average weekly exposure, calculated as AUC24 × 7
In general, overall exposure for NGMN and EE (AUC and Css ) was higher in subjects treated with ZAFEMY for both Cycle 1 and Cycle 2, compared to that for the oral contraceptive, while Cmax values were higher in subjects administered the oral contraceptive. Under steady-state conditions, AUC0-168 and Css for EE were approximately 55% and 60% higher, respectively, for the transdermal patch, and the Cmax was about 35% higher for the oral contraceptive, respectively. Inter-subject variability (%CV) for the PK parameters following delivery from ZAFEMY was higher relative to the variability determined from the oral contraceptive. The mean PK profiles are different between the two products and caution should be exercised when making a direct comparison of these PK parameters.
In Table 7, percent change in concentrations (%CV) of markers of systemic estrogenic activity (Sex Hormone Binding Globulin [SHBG] and Corticosteroid Binding Globulin [CBG]) from Cycle 1 Day 1 to Cycle 1 Day 22 is presented. Percent change in SHBG concentrations was higher for ZAFEMY users compared to women taking the oral contraceptive; percent change in CBG concentrations was similar for ZAFEMY and oral contraceptive users. Within each group, the absolute values for SHBG were similar for Cycle 1, Day 22 and Cycle 2, Day 22.
|Table 7: Mean Percent Change (%CV) in SHBG and CBG Concentrations Following Once-Daily Administration of an Oral Contraceptive (containing NGM 250 mcg / EE 35 mcg) for One Cycle and Application of ZAFEMY for One Cycle in Healthy Female Volunteers|
|Parameter||ZAFEMY (% change from Day 1 to Day 22)||ORAL CONTRACEPTIVE (% change from Day 1 to Day 22)|
|SHBG||334 (39.3)||200 (43.2)|
|CBG||153 (40.2)||157 (33.4)|
In a PK drug interaction study, oral administration of tetracycline HCl, 500 mg four times daily for 3 days prior to and 7 days during wear of ZAFEMY did not significantly affect the PK of NGMN or EE.
Use in Specific Populations
Effects of Age, Body Weight, Body Surface Area and Race
The effects of age, body weight, body surface area and race on the PK of NGMN and EE were evaluated in 230 healthy women from nine pharmacokinetic studies of single 7-day applications of ZAFEMY. For both NGMN and EE, increasing age, body weight and body surface area each were associated with slight decreases in Css and AUC values. However, only a small fraction (10% to 25%) of the overall variability in the PK of NGMN and EE following application of ZAFEMY may be associated with any or all of the above demographic parameters. There was no significant effect of race with respect to Caucasians, Hispanics and Blacks.
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