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Oracea (Doxycycline) - Description and Clinical Pharmacology

 
 



DESCRIPTION

ORACEA (doxycycline, USP) Capsules 40 mg are hard gelatin capsule shells filled with two types of doxycycline beads (30 mg immediate release and 10 mg delayed release) that together provide a dose of 40 mg of anhydrous doxycycline (C22H24N2O8).

The structural formula of doxycycline, USP is:

with an empirical formula of C22H24N2O8•H2O and a molecular weight of 462.46. The chemical designation for doxycycline is 2-Naphthacenecar-boxamide,4-(dimethylamino)-1,4,4a,5,5a,6,11,12a-octahydro-3,5,10,12,12a-pentahydroxy-6-methyl-1,11-dioxo-, [4S-(4α, 4aα, 5α, 5aα, 6α,12aα)]-, monohydrate. It is very slightly soluble in water.

Inert ingredients in the formulation are: hypromellose, iron oxide red, iron oxide yellow, methacrylic acid copolymer, polyethylene glycol, Polysorbate 80, sugar spheres, talc, titanium dioxide, and triethyl citrate. Active ingredients: Each capsule contains doxycycline, USP in an amount equivalent to 40 mg of anhydrous doxycycline.

CLINICAL PHARMACOLOGY

Mechanism of Action

The mechanism of action of ORACEA in the treatment of inflammatory lesions of rosacea is unknown.

Pharmacokinetics

ORACEA capsules are not bioequivalent to other doxycycline products. The pharmacokinetics of doxycycline following oral administration of ORACEA was investigated in 2 volunteer studies involving 61 adults. Pharmacokinetic parameters for ORACEA following single oral doses and at steady-state in healthy subjects are presented in Table 2.

Table 2. Pharmacokinetic Parameters [Mean (±SD)] for ORACEA
N

Cmax*

(ng/mL)

Tmax+(hr)

AUC0-oo*

(ng•hr/mL)

t1/2* (hr)
Single Dose 40 mg capsules 30 510 ± 220.7

3.00

(1.0-4.1)

9227 ± 3212.8 21.2 ± 7.6
Steady-State# 40 mg capsules 31 600 ± 194.2

2.00

(1.0-4.0)

7543 ± 2443.9 23.2 ± 6.2

*Mean +Median #Day 7

Absorption: In a single-dose food-effect study involving administration of ORACEA to healthy volunteers, concomitant administration with a 1000 calorie, high-fat, high-protein meal that included dairy products, resulted in a decrease in the rate and extent of absorption (Cmax and AUC) by about 45% and 22%, respectively, compared to dosing under fasted conditions. This decrease in systemic exposure can be clinically significant, and therefore if ORACEA is taken close to meal times, it is recommended that it be taken at least one hour prior to or two hours after meals.

Distribution: Doxycycline is greater than 90% bound to plasma proteins.

Metabolism: Major metabolites of doxycycline have not been identified. However, enzyme inducers such as barbiturates, carbamazepine, and phenytoin decrease the half-life of doxycycline.

Excretion: Doxycycline is excreted in the urine and feces as unchanged drug. It is reported that between 29% and 55.4% of an administered dose can be accounted for in the urine by 72 hours. Terminal half-life averaged 21.2 hours in subjects receiving a single dose of ORACEA.

Special Populations

Geriatric: Doxycycline pharmacokinetics have not been evaluated in geriatric patients.

Pediatric: Doxycycline pharmacokinetics have not been evaluated in pediatric patients [see Warnings and Precautions (5.1)].

Gender: The pharmacokinetics of ORACEA were compared in 16 male and 14 female subjects under fed and fasted conditions. While female subjects had a higher Cmax and AUC than male subjects, these differences were thought to be due to differences in body weight/lean body mass.

Race: Differences in doxycycline pharmacokinetics among racial groups have not been evaluated.

Renal Insufficiency: Studies have shown no significant difference in serum half-life of doxycycline in patients with normal and severely impaired renal function. Hemodialysis does not alter the serum half-life of doxycycline.

Hepatic Insufficiency: Doxycycline pharmacokinetics have not been evaluated in patients with hepatic insufficiency.

Gastric Insufficiency: In a study in healthy volunteers (N=24) the bioavailability of doxycycline is reported to be reduced at high pH. This reduced bioavailability may be clinically significant in patients with gastrectomy, gastric bypass surgery or who are otherwise deemed achlorhydric.

Drug Interactions: [see Drug Interactions (7)].

Microbiology

Doxycycline is a member of the tetracycline-class of drugs. The plasma concentrations of doxycycline achieved with ORACEA during administration [see Clinical Pharmacology (12.3) and Dosage and Administration (2.2)] are less than the concentration required to treat bacterial diseases. ORACEA should not be used for treating bacterial infections, providing antibacterial prophylaxis, or reducing the numbers or eliminating microorganisms associated with any bacterial disease [see Indications and Usage (1.2)]. In vivo microbiological studies utilizing a similar drug exposure for up to 18 months demonstrated no detectable long term effects on bacterial flora of the oral cavity, skin, intestinal tract and vagina.

NONCLINICAL TOXICOLOGY


Carcinogenesis, Mutagenesis, Impairment of Fertility

Doxycycline was assessed for potential to induce carcinogenesis in a study in which the compound was administered to Sprague-Dawley rats by gavage at dosages of 20, 75, and 200 mg/kg/day for two years. An increased incidence of uterine polyps was observed in female rats that received 200 mg/kg/day, a dosage that resulted in a systemic exposure to doxycycline approximately 12.2 times that observed in female humans who use ORACEA [exposure comparison based upon area under the curve (AUC) values]. No impact upon tumor incidence was observed in male rats up to at 200 mg/kg/day, or in females at the lower dosages studied.

Doxycyline was assessed for potential to induce carcinogenesis in CD-1 mice by gavage at dosages 20, 75, and 150 mg/kg/day in males and at dosages of 20, 100, and 300 mg/kg/day in females. No impact upon tumor incidence was observed in male and female mice at systemic exposures approximately 4.2 and 8.3 times that observed in humans, respectively.

Doxycycline demonstrated no potential to cause genetic toxicity in an in vitro point mutation study with mammalian cells (CHO/HGPRT forward mutation assay) or in an in vivo micronucleus assay conducted in CD-1 mice. However, data from an in vitro mammalian chromosomal aberration assay conducted with CHO cells suggest that doxycycline is a weak clastogen. Oral administration of doxycycline to male and female Sprague-Dawley rats adversely affected fertility and reproductive performance, as evidenced by increased time for mating to occur, reduced sperm motility, velocity, and concentration, abnormal sperm morphology, and increased pre-and post-implantation losses. Doxycycline induced reproductive toxicity at all dosages that were examined in this study, as even the lowest dosage tested (50 mg/kg/day) induced a statistically significant reduction in sperm velocity. Note that 50 mg/kg/day is approximately 3.6 times the amount of doxycycline contained in the recommended daily dose of ORACEA when compared on the basis of AUC estimates. Although doxycycline impairs the fertility of rats when administered at sufficient dosage, the effect of ORACEA on human fertility is unknown.

CLINICAL STUDIES

The safety and efficacy of ORACEA in the treatment of only inflammatory lesions (papules and pustules) of rosacea was evaluated in two randomized, placebo-controlled, multi-centered, double-blind, 16-week Phase 3 trials involving 537 subjects (total of 269 subjects on ORACEA from the two trials) with rosacea (10 to 40 papules and pustules and two or fewer nodules). Pregnant and nursing women, subjects <18 years of age, and subjects with ocular rosacea and/or blepharitis/meibomianitis who require ophthalmologic treatment were excluded from trial. Mean baseline lesion counts were 20 and 21 for ORACEA and placebo subject groups respectively.

At Week 16, subjects in the ORACEA group were evaluated using co-primary endpoints of mean reduction in lesion counts and a dichotomized static Investigators Global Assessment of Clear or Almost Clear (defined as 1 to 2 small papules or pustules) when compared to the placebo group in both Phase 3 trials.

Table 3: Clinical Results of ORACEA versus Placebo
Study 1 Study 2
ORACEA Placebo ORACEA Placebo

40 mg

N=127

N=124

40 mg

N=142

N=144

Mean Change in

Lesion Count from Baseline

-11.8 -5.9 -9.5 -4.3

No. (%) of Subjects Clear

or Almost Clear in the IGA*

39 (30.7%) 24 (19.4%) 21 (14.8%) 9 (6.3%)

*Investigator’s Global Assessment

Subjects treated with ORACEA did not demonstrate significant improvement in erythema when compared to those treated with placebo.

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