Striant

STRIANT- testosterone tablet
Columbia Laboratories, Inc.

DESCRIPTION

Striant® (testosterone buccal system) is designed to adhere to the gum or inner cheek. It provides a controlled and sustained release of testosterone through the buccal mucosa as the buccal system gradually hydrates. Insertion of Striant® twice a day, in the morning and in the evening, provides continuous systemic delivery of testosterone.

Striant® is a white to off-white colored, monoconvex, tablet-like, mucoadhesive buccal system. Striant® adheres to the gum tissue above the incisors, with the flat surface facing the cheek mucosa.

The active ingredient in Striant® is testosterone. Each buccal system contains 30 mg of testosterone. Testosterone USP is practically white crystalline powder chemically described as 17-beta hydroxyandrost-4-en-3one.

Chemical Structure:

Chemical Structure
(click image for full-size original)

Other pharmacologically inactive ingredients in Striant® are anhydrous lactose NF, carbomer 934P, hypromellose USP, magnesium stearate NF, lactose monohydrate NF, polycarbophil USP, colloidal silicon dioxide NF, starch NF and talc USP.

CLINICAL PHARMACOLOGY

Striant® delivers physiologic amounts of testosterone to the systemic circulation, thereby producing circulating testosterone concentrations in hypogonadal males that approximate physiologic levels seen in healthy young men (300 — 1050 ng/dL).

Testosterone — General Androgen Effects

Endogenous androgens, including testosterone and dihydrotestosterone (DHT) are responsible for the normal growth and development of the male sex organs and for maintenance of secondary sex characteristics. These effects include the growth and maturation of prostate, seminal vesicles, penis, and scrotum; the development of male hair distribution, such as facial, pubic, chest, and axillary hair; laryngeal enlargement, vocal chord thickening, and alterations in body musculature and fat distribution. Testosterone and DHT are necessary for the normal development of secondary sex characteristics.

Male hypogonadism results from insufficient production of testosterone and is characterized by low serum testosterone concentrations. Symptoms associated with male hypogonadism include impotence and decreased sexual desire, fatigue and loss of energy, mood depression, regression of secondary sexual characteristics and osteoporosis. Hypogonadism is a risk factor for osteoporosis in men.

Drugs in the androgen class also promote retention of nitrogen, sodium, potassium, phosphorus, and decreased urinary excretion of calcium. Androgens have been reported to increase protein anabolism and decrease protein catabolism. Nitrogen balance is improved only when there is sufficient intake of calories and protein.

Androgens are responsible for the growth spurt of adolescence and for the eventual termination of linear growth brought about by fusion of the epiphyseal growth centers. In children, exogenous androgens accelerate linear growth rates but may cause a disproportionate advancement in bone maturation. Use by children and adolescents over long periods may result in fusion of the epiphyseal growth centers and termination of the growth process. Androgens have been reported to stimulate the production of red blood cells by enhancing the production of erythropoietin.

During exogenous administration of androgens, endogenous testosterone release may be inhibited through feedback inhibition of pituitary luteinizing hormone (LH). At large doses of exogenous androgens, spermatogenesis may also be suppressed through feedback inhibition of pituitary follicle-stimulating hormone (FSH).

Pharmacokinetics

Absorption

When applied to the buccal mucosa, Striant® slowly releases testosterone, allowing for absorption of testosterone through gum and cheek surfaces that are in contact with the buccal system. Since venous drainage from the mouth is to the superior vena cava, trans-buccal delivery of testosterone circumvents first-pass (hepatic) metabolism.

Following the initial application of Striant® , the serum testosterone concentration rises to a maximum within 10-12 hours. The mean maximum (C max ) and mean average serum total testosterone concentrations for the 12 hour dosing period (C avg(0-12) ) are within the normal physiologic range.

Striant® is intended for twice daily dosing. Serum concentrations of testosterone reach steady-state levels after the second dose of twice daily Striant® dosing. Following removal of Striant® , the serum testosterone concentration decreases to a level below the normal range within 2-4 hours.

With twice-daily repeated dosing, mean pharmacokinetic parameters at steady-state for total testosterone serum concentration were very similar between studies of 7-day and 12-week dosing durations. Mean C avg(0-24) across the studies ranged from 520 to 550 ng/dL and these mean values were within the physiologic range (see Table 1).

Table 1. Mean (±SD) Steady-State Serum Total Testosterone Concentrations During Treatment with Striant® (on Final Day of Treatment)
Study 1 Study 2
12-weeks(N=82) 7-days(N=29)
C avg(0-24) (ng/dL) 520 (±205) 550 (±169)
C max(0-24) (ng/dL) 970 (±442) 910 (±319)
C min(0-24) (ng/dL) 290 (±130) 320 (±131)

Although no specific food effect study was conducted, pivotal Phase 3 study results showed that consumption of food and beverage did not significantly affect the absorption of testosterone from Striant®.

The effects of toothbrushing, mouthwashing, chewing gum and alcoholic beverages on the use and absorption of Striant® were not investigated in controlled studies, however, Phase 3 clinical studies permitted patients to do these activities indicating the use of Striant® was not significantly affected by these activities.

Distribution

Circulating testosterone is chiefly bound in the serum to sex hormone-binding globulin (SHBG) and albumin. The albumin-bound fraction of testosterone easily dissociates from albumin and is presumed to be bioactive. The portion of testosterone bound to SHBG is not considered biologically active. The amount of SHBG in the serum and the total testosterone level will determine the distribution of bioactive and nonbioactive androgen. SHBG-binding capacity is high in prepubertal children, declines during puberty and adulthood, and increases again during the later decades of life. Approximately 40% of testosterone in plasma is bound to SHBG, 2% remains unbound (free) and the rest is bound to albumin and other proteins.

Metabolism

There is considerable variation in the half-life of testosterone as reported in the literature, ranging from ten to 100 minutes. Testosterone is metabolized to various 17-keto steroids through two different pathways, and the major active metabolites are estradiol and dihydrotestosterone (DHT). DHT binds with greater affinity to SHBG than does testosterone. In many tissues the activity of testosterone appears to depend on reduction to DHT, which binds to cytosol receptor proteins. The steroid-receptor complex is transported to the nucleus where it initiates transcription and cellular changes related to androgen action. In reproductive tissues, DHT is further metabolized to 3-alpha and 3-beta androstanediol.

Mean DHT concentrations increase in parallel with testosterone concentrations during Striant® treatment. After 24 hours of treatment, mean DHT serum concentrations are within normal range. The mean steady-state T/DHT ratio during treatment with Striant® remained within normal limits as determined by the analytical laboratory involved with the clinical trials. These ratios ranged from approximately 9-12.

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