Teriparatide (rDNA origin) 003579

Categories, Drug Classes, Brand Names & Cost Of Therapy

Categories: Osteoporosis; Pregnancy Category C; FDA Approved 2002 Nov

Drug Classes: Hormones/hormone modifiers

Brand Names: Forteo

Warning

Description

Teriparatide has a molecular weight of 4117.8 daltons.

Teriparatide (rDNA origin) is manufactured by Eli Lilly and Company using a strain of Escherichia coli modified by recombinant DNA technology. Forteo is supplied as a sterile, colorless, clear, isotonic solution in a glass cartridge which is pre-assembled into a disposable pen device for subcutaneous injection. Each prefilled delivery device is filled with 3.3 ml to deliver 3 ml. Each ml contains 250 µg teriparatide (corrected for acetate, chloride, and water content), 0.41 mg glacial acetic acid, 0.10 mg sodium acetate (anhydrous), 45.4 mg mannitol, 3.0 mg metacresol, and water for injection. In addition, hydrochloric acid solution 10% and/or sodium hydroxide solution 10% may have been added to adjust the product to pH 4.

Each cartridge pre-assembled into a pen device delivers 20 µg of teriparatide per dose each day for up to 28 days.

See User Manual: Instructions for Use that accompany the package insert.

Clinical Pharmacology

Endogenous 84-amino-acid parathyroid hormone (PTH) is the primary regulator of calcium and phosphate metabolism in bone and kidney. Physiological actions of PTH include regulation of bone metabolism, renal tubular reabsorption of calcium and phosphate, and intestinal calcium absorption. The biological actions of PTH and teriparatide are mediated through binding to specific high-affinity cell-surface receptors. Teriparatide and the 34 N-terminal amino acids of PTH bind to these receptors with the same affinity and have the same physiological actions on bone and kidney. Teriparatide is not expected to accumulate in bone or other tissues.

The skeletal effects of teriparatide depend upon the pattern of systemic exposure. Once-daily administration of teriparatide stimulates new bone formation on trabecular and cortical (periosteal and/or endosteal) bone surfaces by preferential stimulation of osteoblastic activity over osteoclastic activity. In monkey studies, teriparatide improved trabecular microarchitecture and increased bone mass and strength by stimulating new bone formation in both cancellous and cortical bone. In humans, the anabolic effects of teriparatide are manifest as an increase in skeletal mass, an increase in markers of bone formation and resorption, and an increase in bone strength. By contrast, continuous excess of endogenous PTH, as occurs in hyperparathyroidism, may be detrimental to the skeleton because bone resorption may be stimulated more than bone formation.

Human Pharmacokinetics

Teriparatide is extensively absorbed after subcutaneous injection; the absolute bioavailability is approximately 95% based on pooled data from 20-, 40-, and 80 µg doses. The rates of absorption and elimination are rapid. The peptide reaches peak serum concentrations about 30 minutes after subcutaneous injection of a 20 µg dose and declines to non-quantifiable concentrations within 3 hours.

Systemic clearance of teriparatide (approximately 62 L/h in women and 94 L/h in men) exceeds the rate of normal liver plasma flow, consistent with both hepatic and extra-hepatic clearance. Volume of distribution, following intravenous injection, is approximately 0.12 L/kg. Intersubject variability in systemic clearance and volume of distribution is 25-50%. The half-life of teriparatide in serum is 5 minutes when administered by intravenous injection and approximately 1 hour when administered by subcutaneous injection. The longer half-life following subcutaneous administration reflects the time required for absorption from the injection site.

No metabolism or excretion studies have been performed with teriparatide. However, the mechanisms of metabolism and elimination of PTH(1-34) and intact PTH have been extensively described in published literature. Peripheral metabolism of PTH is believed to occur by non-specific enzymatic mechanisms in the liver followed by excretion via the kidneys.

Special Populations

Pediatric

Pharmacokinetic data in pediatric patients are not available (see WARNINGS).

Geriatric

No age-related differences in teriparatide pharmacokinetics were detected (range 31-85 years).

Gender

Although systemic exposure to teriparatide was approximately 20-30% lower in men than women, the recommended dose for both genders is 20 µg/day.

Race

The populations included in the pharmacokinetic analyses were 98.5% Caucasian. The influence of race has not been determined.

Renal Insufficiency

No pharmacokinetic differences were identified in 11 patients with mild or moderate renal insufficiency [creatinine clearance (CrCl) 30-72 ml/min] administered a single dose of teriparatide. In 5 patients with severe renal insufficiency (CrCl <30 ml/min), the AUC and T_½ of teriparatide were increased by 73% and 77%, respectively. Maximum serum concentration of teriparatide was not increased. No studies have been performed in patients undergoing dialysis for chronic renal failure (see PRECAUTIONS).

Heart Failure

No clinically relevant pharmacokinetic, blood pressure, or pulse rate differences were identified in 13 patients with stable New York Heart Association Class I to III heart failure after the administration of two 20 µg doses of teriparatide.

Hepatic Insufficiency

Non-specific proteolytic enzymes in the liver (possibly Kupffer cells) cleave PTH(1-34) and PTH(1-84) into fragments that are cleared from the circulation mainly by the kidney. No studies have been performed in patients with hepatic impairment.

Drug Interactions

Hydrochlorothiazide

In a study of 20 healthy people, the coadministration of hydrochlorothiazide 25 mg with teriparatide did not affect the serum calcium response to teriparatide 40 µg. The 24 hour urine excretion of calcium was reduced by a clinically unimportant amount (15%). The effect of coadministration of a higher dose of hydrochlorothiazide with teriparatide on serum calcium levels has not been studied.

Furosemide

In a study of 9 healthy people and 17 patients with mild, moderate, or severe renal insufficiency (CrCl 13-72 ml/min), coadministration of intravenous furosemide (20-100 mg) with teriparatide 40 µg resulted in small increases in the serum calcium (2%) and 24 hour urine calcium (37%) responses to teriparatide that did not appear to be clinically important.

Human Pharmacodynamics

Effects on Mineral Metabolism

Teriparatide affects calcium and phosphorus metabolism in a pattern consistent with the known actions of endogenous PTH (e.g., increases serum calcium and decreases serum phosphorus).

Serum Calcium Concentrations

When teriparatide 20 µg is administered once daily, the serum calcium concentration increases transiently, beginning approximately 2 hours after dosing and reaching a maximum concentration between 4 and 6 hours (median increase, 0.4 mg/dl). The serum calcium concentration begins to decline approximately 6 hours after dosing and returns to baseline by 16-24 hours after each dose.

In a clinical study of postmenopausal women with osteoporosis, the median peak serum calcium concentration measured 4-6 hours after dosing with teriparatide 20 µg was 2.42 mmol/L (9.68 mg/dl) at 12 months. The peak serum calcium remained below 2.76 mmol/L (11.0 mg/dl) in >99% of women at each visit. Sustained hypercalcemia was not observed.

In this study, 11.1% of women treated with teriparatide had at least 1 serum calcium value above the upper limit of normal [2.64 mmol/L (10.6 mg/dl)] compared with 1.5% of women treated with placebo. The percentage of women treated with teriparatide whose serum calcium was above the upper limit of normal on consecutive 4-6 hour post-dose measurements was 3.0% compared with 0.2% of women treated with placebo. In these women, calcium supplements and/or teriparatide doses were reduced. The timing of these dose reductions was at the discretion of the investigator. Teriparatide dose adjustments were made at varying intervals after the first observation of increased serum calcium (median 21 weeks). During these intervals, there was no evidence of progressive increases in serum calcium.

In a clinical study of men with either primary or hypogonadal osteoporosis, the effects on serum calcium were similar to those observed in postmenopausal women. The median peak serum calcium concentration measured 4-6 hours after dosing with teriparatide was 2.35 mmol/L (9.44 mg/dl) at 12 months. The peak serum calcium remained below 2.76 mmol/L (11.0 mg/dl) in 98% of men at each visit. Sustained hypercalcemia was not observed.

In this study, 6.0% of men treated with teriparatide daily had at least 1 serum calcium value above the upper limit of normal [2.64 mmol/L (10.6 mg/dl)] compared with none of the men treated with placebo. The percentage of men treated with teriparatide whose serum calcium was above the upper limit of normal on consecutive measurements was 1.3% (2 men) compared with none of the men treated with placebo. Although calcium supplements and/or teriparatide doses could have been reduced in these men, only calcium supplementation was reduced (see PRECAUTIONS and ADVERSE REACTIONS).

In a clinical study of women previously treated for 18-39 months with raloxifene (n=26) or alendronate (n=33), mean serum calcium >12 hours after teriparatide injection was increased by 0.09-0.14 mmol/L (0.36-0.56 mg/dl), after 1-6 months of teriparatide treatment compared with baseline. Of the women pretreated with raloxifene, 3 (11.5%) had a serum calcium >2.76 mmol/L (11.0 mg/dl), and of those pretreated with alendronate, 3 (9.1%) had a serum calcium >2.76 mmol/L (11.0 mg/dl). The highest serum calcium reported was 3.12 mmol/L (12.5 mg/dl). None of the women had symptoms of hypercalcemia. There were no placebo controls in this study.

Urinary Calcium Excretion

In a clinical study of postmenopausal women with osteoporosis who received 1000 mg of supplemental calcium and at least 400 IU of vitamin D, daily teriparatide increased urinary calcium excretion. The median urinary excretion of calcium was 4.8 mmol/day (190 mg/day) at 6 months and 4.2 mmol/day (170 mg/day) at 12 months. These levels were 0.76 mmol/day (30 mg/day) and 0.30 mmol/day (12 mg/day) higher, respectively, than in women treated with placebo. The incidence of hypercalciuria (>7.5 mmol Ca/day or 300 mg/day) was similar in the women treated with teriparatide or placebo.

In a clinical study of men with either primary or hypogonadal osteoporosis who received 1000 mg of supplemental calcium and at least 400 IU of vitamin D, daily teriparatide had inconsistent effects on urinary calcium excretion. The median urinary excretion of calcium was 5.6 mmol/day (220 mg/day) at 1 month and 5.3 mmol/day (210 mg/day) at 6 months. These levels were 0.50 mmol/day (20 mg/day) higher and 0.20 mmol/day (8.0 mg/day) lower, respectively, than in men treated with placebo. The incidence of hypercalciuria (>7.5 mmol Ca/day or 300 mg/day) was similar in the men treated with teriparatide or placebo.

Phosphorus and Vitamin D

In single-dose studies, teriparatide produced transient phosphaturia and mild transient reductions in serum phosphorus concentration. However, hypophosphatemia (<0.74 mmol/L or 2.4 mg/dl) was not observed in clinical trials with teriparatide.

In clinical trials of daily teriparatide, the median serum concentration of 1,25-dihydroxyvitamin D was increased at 12 months by 19% in women and 14% in men, compared with baseline. In the placebo group, this concentration decreased by 2% in women and increased by 5% in men. The median serum 25-hydroxyvitamin D concentration at 12 months was decreased by 19% in women and 10% in men compared with baseline. In the placebo group, this concentration was unchanged in women and increased by 1% in men.

Effects on Markers of Bone Turnover

Daily administration of teriparatide to men and postmenopausal women with osteoporosis in clinical studies stimulated bone formation, as shown by increases in the formation markers serum bone-specific alkaline phosphatase (BSAP) and procollagen I carboxy-terminal propeptide (PICP). Data on biochemical markers of bone turnover were available for the first 12 months of treatment. Peak concentrations of PICP at 1 month of treatment were approximately 41% above baseline, followed by a decline to near-baseline values by 12 months. BSAP concentrations increased by 1 month of treatment and continued to rise more slowly from 6 through 12 months. The maximum increases of BSAP were 45% above baseline in women and 23% in men. After discontinuation of therapy, BSAP concentrations returned toward baseline. The increases in formation markers were accompanied by secondary increases in the markers of bone resorption: urinary N-telopeptide (NTX) and urinary deoxypyridinoline (DPD), consistent with the physiological coupling of bone formation and resorption in skeletal remodeling. Changes in BSAP, NTX, and DPD were lower in men than in women, possibly because of lower systemic exposure to teriparatide in men.

Clinical Studies

The safety and efficacy of once-daily teriparatide, median exposure of 19 months, were examined in a double-blind, placebo-controlled clinical study of 1637 postmenopausal women with osteoporosis (teriparatide 20 µg, n=541).

This multicenter study was performed in the US and 16 other countries. All women received 1000 mg of calcium per day and at least 400 IU of vitamin D per day. Baseline and endpoint spinal radiographs were evaluated using the semiquantitative scoring method of Genant et al [J Bone Miner Res 1993;8(9):1137-48]. Ninety percent (90%) of the women in the study had 1 or more radiographically diagnosed vertebral fractures at baseline. The primary efficacy endpoint was the occurrence of new radiographically diagnosed vertebral fractures defined as changes in the height of previously undeformed vertebrae. Such fractures are not necessarily symptomatic.

Effect on Fracture Incidence

New Vertebral Fractures

Teriparatide, when taken with calcium and vitamin D and compared with calcium and vitamin D alone, reduced the risk of 1 or more new vertebral fractures from 14.3% of women in the placebo group to 5.0% in the teriparatide group. This difference was statistically significant (p <0.001); the absolute reduction in risk was 9.3% and the relative reduction was 65%. Teriparatide was effective in reducing the risk for vertebral fractures regardless of age, baseline rate of bone turnover, or baseline BMD.

New Nonvertebral Osteoporotic Fractures

TABLE 2 shows the effect of teriparatide on the risk of nonvertebral fractures. Teriparatide significantly reduced the risk of any nonvertebral fracture from 5.5% in the placebo group to 2.6% in the teriparatide group (p <0.05). The absolute reduction in risk was 2.9% and the relative reduction was 53%.

The cumulative percentage of postmenopausal women with osteoporosis who sustained new nonvertebral fractures was lower in women treated with teriparatide than in women treated with placebo.

Effect on Bone Mineral Density (BMD)

Teriparatide increased lumbar spine BMD in postmenopausal women with osteoporosis. Statistically significant increases were seen at 3 months and continued throughout the treatment period.

Postmenopausal women with osteoporosis who were treated with teriparatide also had statistically significant increases in BMD at the femoral neck, total hip, and total body (see TABLE 3).

Teriparatide treatment increased lumbar spine BMD from baseline in 96% of postmenopausal women treated. Seventy-two percent (72%) of patients treated with teriparatide achieved at least a 5% increase in spine BMD, and 44% gained 10% or more.

Both treatment groups lost height during the trial. The mean decreases were 3.61 and 2.81 mm in the placebo and teriparatide groups, respectively.

Bone Histology

The effects of teriparatide on bone histology were evaluated in iliac crest biopsies of 35 postmenopausal women treated for 12-24 months with calcium and vitamin D and teriparatide 20 or 40 µg/day. Normal mineralization was observed with no evidence of cellular toxicity. The new bone formed with teriparatide was of normal quality (as evidenced by the absence of woven bone and marrow fibrosis).

Treatment to Increase Bone Mass in Men With Primary or Hypogonadal Osteoporosis

The safety and efficacy of once-daily teriparatide, median exposure of 10 months, were examined in a double-blind, placebo-controlled clinical study of 437 men with either primary (idiopathic) or hypogonadal osteoporosis (teriparatide 20 µg, n=151). This multicenter efficacy study was performed in the US and 10 other countries. All men received 1000 mg of calcium per day and at least 400 IU of vitamin D per day. The primary efficacy endpoint was change in lumbar spine BMD.

Teriparatide increased lumbar spine BMD in men with primary or hypogonadal osteoporosis. Statistically significant increases were seen at 3 months and continued throughout the treatment period. Teriparatide was effective in increasing lumbar spine BMD regardless of age, baseline rate of bone turnover, and baseline BMD. The effects of teriparatide at additional skeletal sites are shown in TABLE 4.

Teriparatide treatment for a median of 10 months increased lumbar spine BMD from baseline in 94% of men treated. Fifty-three percent (53%) of patients treated with teriparatide achieved at least a 5% increase in spine BMD, and 14% gained 10% or more.

Indications And Usage

Teriparatide is indicated to increase bone mass in men with primary or hypogonadal osteoporosis who are at high risk for fracture. These include men with a history of osteoporotic fracture, or who have multiple risk factors for fracture, or who have failed or are intolerant to previous osteoporosis therapy, based upon physician assessment (see BOXED WARNING). In men with primary or hypogonadal osteoporosis, teriparatide increases BMD. The effects of teriparatide on risk for fracture in men have not been studied.

Contraindications

Warnings

The following categories of patients have increased baseline risk of osteosarcoma and therefore should not be treated with teriparatide:

Patients with bone metastases or a history of skeletal malignancies should be excluded from treatment with teriparatide.

Patients with metabolic bone diseases other than osteoporosis should be excluded from treatment with teriparatide.

Teriparatide has not been studied in patients with pre-existing hypercalcemia. These patients should be excluded from treatment with teriparatide because of the possibility of exacerbating hypercalcemia.

Precautions

The safety and efficacy of teriparatide have not been evaluated beyond 2 years of treatment. Consequently, use of the drug for more than 2 years is not recommended.

In clinical trials, the frequency of urolithiasis was similar in patients treated with teriparatide and placebo. However, teriparatide has not been studied in patients with active urolithiasis. If active urolithiasis or pre-existing hypercalciuria are suspected, measurement of urinary calcium excretion should be considered. Teriparatide should be used with caution in patients with active or recent urolithiasis because of the potential to exacerbate this condition.

Hypotension

In short-term clinical pharmacology studies with teriparatide, transient episodes of symptomatic orthostatic hypotension were observed infrequently. Typically, an event began within 4 hours of dosing and spontaneously resolved within a few minutes to a few hours. When transient orthostatic hypotension occurred, it happened within the first several doses, it was relieved by placing the person in a reclining position, and it did not preclude continued treatment.

Concomitant Treatment With Digitalis

In a study of 15 healthy people administered digoxin daily to steady state, a single teriparatide dose did not alter the effect of digoxin on the systolic time interval (from electrocardiographic Q-wave onset to aortic valve closure, a measure of digoxin’s calcium-mediated cardiac effect). However, sporadic case reports have suggested that hypercalcemia may predispose patients to digitalis toxicity. Because teriparatide transiently increases serum calcium, teriparatide should be used with caution in patients taking digitalis.

Hepatic, Renal, and Cardiac

Limited information is available to evaluate safety in patients with hepatic, renal, and cardiac disease.

Information for the Patient

For safe and effective use of teriparatide, the physician should inform patients about the following:

Laboratory Tests

Serum Calcium

Teriparatide transiently increases serum calcium, with the maximal effect observed at approximately 4-6 hours post-dose. By 16 hours post-dose, serum calcium generally has returned to or near baseline. These effects should be kept in mind because serum calcium concentrations observed within 16 hours after a dose may reflect the pharmacologic effect of teriparatide. Persistent hypercalcemia was not observed in clinical trials with teriparatide. If persistent hypercalcemia is detected, treatment with teriparatide should be discontinued pending further evaluation of the cause of hypercalcemia.

Patients known to have an underlying hypercalcemic disorder, such as primary hyperparathyroidism, should not be treated with teriparatide (see WARNINGS).

Urinary Calcium

Teriparatide increases urinary calcium excretion, but the frequency of hypercalciuria in clinical trials was similar for patients treated with teriparatide and placebo (see CLINICAL PHARMACOLOGY, Human Pharmacodynamics).

Renal Function

No clinically important adverse renal effects were observed in clinical studies. Assessments included creatinine clearance; measurements of blood urea nitrogen (BUN), creatinine, and electrolytes in serum; urine specific gravity and pH; and examination of urine sediment. Long-term evaluation of patients with severe renal insufficiency, patients undergoing acute or chronic dialysis, or patients who have functioning renal transplants has not been performed.

Serum Uric Acid

Teriparatide increases serum uric acid concentrations. In clinical trials, 2.8% of teriparatide patients had serum uric acid concentrations above the upper limit of normal compared with 0.7% of placebo patients. However, the hyperuricemia did not result in an increase in gout, arthralgia, or urolithiasis.

Carcinogenesis, Mutagenesis, and Impairment of Fertility

Carcinogenesis

Two carcinogenicity bioassays were conducted in Fischer 344 rats. In the first study, male and female rats were given daily subcutaneous teriparatide injections of 5, 30, or 75 µg/kg/day for 24 months from 2 months of age. These doses resulted in systemic exposures that were, respectively, 3, 20, and 60 times higher than the systemic exposure observed in humans following a subcutaneous dose of 20 µg (based on AUC comparison). Teriparatide treatment resulted in a marked dose-related increase in the incidence of osteosarcoma, a rare malignant bone tumor, in both male and female rats. Osteosarcomas were observed at all doses and the incidence reached 40-50% in the high-dose groups. Teriparatide also caused a dose-related increase in osteoblastoma and osteoma in both sexes. No osteosarcomas, osteoblastomas or osteomas were observed in untreated control rats. The bone tumors in rats occurred in association with a large increase in bone mass and focal osteoblast hyperplasia.

The second 2 year study was carried out in order to determine the effect of treatment duration and animal age on the development of bone tumors. Female rats were treated for different periods between 2 and 26 months of age with subcutaneous doses of 5 and 30 µg/kg (equivalent to 3 and 20 times the human exposure at the 20 µg dose, based on AUC comparison). The study showed that the occurrence of osteosarcoma, osteoblastoma and osteoma was dependent upon dose and duration of exposure. Bone tumors were observed when immature 2 month old rats were treated with 30 µg/kg/day for 24 months or with 5 or 30 µg/kg/day for 6 months. Bone tumors were also observed when mature 6 month old rats were treated with 30 µg/kg/day for 6 or 20 months. Tumors were not detected when mature 6 month old rats were treated with 5 µg/kg/day for 6 or 20 months. The results did not demonstrate a difference in susceptibility to bone tumor formation, associated with teriparatide treatment, between mature and immature rats.

The relevance of these rat findings to humans is uncertain.

Mutagenesis

Teriparatide was not genotoxic in any of the following test systems: the Ames test for bacterial mutagenesis; the mouse lymphoma assay for mammalian cell mutation; the chromosomal aberration assay in Chinese hamster ovary cells, with and without metabolic activation; and the in vivo micronucleus test in mice.

Impairment of Fertility

No effects on fertility were observed in male and female rats given subcutaneous teriparatide doses of 30, 100, or 300 µg/kg/day prior to mating and in females continuing through gestation Day 6 (16-160 times the human dose of 20 µg based on surface area, µg/m² ).

Pregnancy Category C

In pregnant rats given subcutaneous teriparatide doses up to 1000 µg/kg/day, there were no findings. In pregnant mice given subcutaneous doses of 225 or 1000 µg/kg/day (≥60 times the human dose based on surface area, µg/m² ) from gestation Day 6 through 15, the fetuses showed an increased incidence of skeletal deviations or variations (interrupted rib, extra vertebra or rib).

Developmental effects in a perinatal/postnatal study in pregnant rats given subcutaneous doses of teriparatide from gestation Day 6 through postpartum Day 20 included mild growth retardation in female offspring at doses ≥225 µg/kg/day (≥120 times the human dose based on surface area, µg/m² ), and in male offspring at 1000 µg/kg/day (540 times the human dose based on surface area, µg/m² ). There was also reduced motor activity in both male and female offspring at 1000 µg/kg/day. There were no developmental or reproductive effects in mice or rats at a dose of 30 µg/kg (8 or 16 times the human dose based on surface area, µg/m² ). The effect of teriparatide treatment on human fetal development has not been studied. Teriparatide is not indicated for use in pregnancy.

Nursing Mothers

Because teriparatide is indicated for the treatment of osteoporosis in postmenopausal women, it should not be administered to women who are nursing their children. There have been no clinical studies to determine if teriparatide is secreted into breast milk.

Pediatric Use

The safety and efficacy of teriparatide have not been established in pediatric populations. Teriparatide is not indicated for use in pediatric patients (see WARNINGS).

Geriatric Use

Of the patients receiving teriparatide in the osteoporosis trial of 1637 postmenopausal women, 75% were 65 years of age and over and 23% were 75 years of age and over. Of the patients receiving teriparatide in the osteoporosis trial of 437 men, 39% were 65 years of age and over and 13% were 75 years of age and over. No significant differences in bone response or adverse reactions were seen in geriatric patients receiving teriparatide as compared with younger patients. Nonetheless, as with many medications, elderly patients may have greater sensitivity to the adverse effects of teriparatide.

Adverse Reactions

In the two Phase 3 placebo-controlled clinical trials in men and postmenopausal women, early discontinuation due to adverse events occurred in 5.6% of patients assigned to placebo and 7.1% of patients assigned to teriparatide. Reported adverse events that appeared to be increased by teriparatide treatment were dizziness and leg cramps.

TABLE 5 lists adverse events that occurred in the two Phase 3 placebo-controlled clinical trials in men and postmenopausal women at a frequency ≥2.0% in the teriparatide groups and in more teriparatide-treated patients than in placebo-treated patients, without attribution of causality.

Serum Calcium

Teriparatide transiently increases serum calcium, with the maximal effect observed at approximately 4-6 hours post-dose. Serum calcium measured at least 16 hours post-dose was not different from pretreatment levels. In clinical trials, the frequency of at least 1 episode of transient hypercalcemia in the 4-6 hours after teriparatide administration was increased from 1.5% of women and none of the men treated with placebo to 11.1% of women and 6.0% of men treated with teriparatide. The number of patients treated with teriparatide whose transient hypercalcemia was verified on consecutive measurements was 3.0% of women and 1.3% of men.

Immunogenicity

In a large clinical trial, antibodies that cross-reacted with teriparatide were detected in 2.8% of women receiving teriparatide. Generally, antibodies were first detected following 12 months of treatment and diminished after withdrawal of therapy. There was no evidence of hypersensitivity reactions, allergic reactions, effects on serum calcium, or effects on BMD response.

Overdosage

In single-dose rodent studies using subcutaneous injection of teriparatide, no mortality was seen in rats given doses of 1000 µg/kg (540 times the human dose based on surface area, µg/m² ) or in mice given 10,000 µg/kg (2700 times the human dose based on surface area, µg/m² ).

Overdose Management

There is no specific antidote for teriparatide. Treatment of suspected overdose should include discontinuation of teriparatide, monitoring of serum calcium and phosphorus, and implementation of appropriate supportive measures, such as hydration.

Dosage And Administration

Teriparatide should be administered initially under circumstances in which the patient can sit or lie down if symptoms of orthostatic hypotension occur (see PRECAUTIONS, Information for the Patient).

Teriparatide is a clear and colorless liquid. Do not use if solid particles appear or if the solution is cloudy or colored. The teriparatide pen should not be used past the stated expiration date.

No data are available on the safety or efficacy of intravenous or intramuscular injection of teriparatide.

The safety and efficacy of teriparatide have not been evaluated beyond 2 years of treatment. Consequently, use of the drug for more than 2 years is not recommended.

Instructions for Pen Use

Patients and caregivers who administer teriparatide should receive appropriate training and instruction on the proper use of the teriparatide pen from a qualified health professional. It is important to read, understand, and follow the instructions in the teriparatide pen User Manual for priming the pen and dosing. Failure to do so may result in inaccurate dosing. Each teriparatide pen can be used for up to 28 days after the first injection. After the 28 day use period, discard the teriparatide pen, even if it still contains some unused solution. Never share a teriparatide pen.

How Supplied

Storage

The Forteo pen should be stored under refrigeration at 2-8°C (36-46°F) at all times. Recap the pen when not in use to protect the cartridge from physical damage and light. During the use period, time out of the refrigerator should be minimized; the dose may be delivered immediately following removal from the refrigerator.

Do not freeze. Do not use Forteo if it has been frozen.