Source: European Medicines Agency (EU) Revision Year: 2021 Publisher: N.V. Organon, Kloosterstraat 6, 5349 AB Oss, The Netherlands
Pharmacotherapeutic group: Drugs for treatment of bone diseases, Bisphosphonates, combinations
ATC code: M05BB03
Alendronate sodium is a bisphosphonate that inhibits osteoclastic bone resorption with no direct effect on bone formation. Preclinical studies have shown preferential localisation of alendronate to sites of active resorption. Activity of osteoclasts is inhibited, but recruitment or attachment of osteoclasts is not affected. The bone formed during treatment with alendronate is of normal quality.
Vitamin D3 is produced in the skin by conversion of 7-dehydrocholesterol to vitamin D3 by ultraviolet light. In the absence of adequate sunlight exposure, vitamin D3 is an essential dietary nutrient. Vitamin D3 is converted to 25-hydroxyvitamin D3 in the liver, and stored until needed. Conversion to the active calcium-mobilising hormone 1,25-dihydroxyvitamin D3 (calcitriol) in the kidney is tightly regulated. The principal action of 1,25-dihydroxyvitamin D3 is to increase intestinal absorption of both calcium and phosphate as well as regulate serum calcium, renal calcium and phosphate excretion, bone formation and bone resorption.
Vitamin D3 is required for normal bone formation. Vitamin D insufficiency develops when both sunlight exposure and dietary intake are inadequate. Insufficiency is associated with negative calcium balance, bone loss, and increased risk of skeletal fracture. In severe cases, deficiency results in secondary hyperparathyroidism, hypophosphataemia, proximal muscle weakness and osteomalacia, further increasing the risk of falls and fractures in osteoporotic individuals. Supplemental vitamin D reduces these risks and their consequences.
Osteoporosis is defined as bone mineral density (BMD) of the spine or hip 2.5 standard deviations (SD) below the mean value of a normal young population or as a previous fragility fracture, irrespective of BMD.
The effect of the lower dose of FOSAVANCE (alendronate 70 mg/vitamin D3 2,800 IU) on vitamin D status was demonstrated in a 15-week, multinational study that enrolled 682 osteoporotic post-menopausal women (serum 25-hydroxyvitamin D at baseline: mean, 56 nmol/l [22.3 ng/ml]; range, 22.5-225 nmol/l [9-90 ng/ml]). Patients received the lower strength (70 mg/2,800 IU) of FOSAVANCE (n=350) or FOSAMAX (alendronate) 70 mg (n=332) once a week; additional vitamin D supplements were prohibited. After 15 weeks of treatment, the mean serum 25-hydroxyvitamin D levels were significantly higher (26%) in the FOSAVANCE (70 mg/2,800 IU) group (56 nmol/l [23 ng/ml]) than in the alendronate-only group (46 nmol/l [18.2 ng/ml]). The percentage of patients with vitamin D insufficiency (serum 25-hydroxyvitamin D <37.5 nmol/l [<15 ng/ml]) was significantly reduced by 62.5% with FOSAVANCE (70 mg/2,800 IU) vs. alendronate-only (12% vs. 32%, respectively), through week 15. The percentage of patients with vitamin D deficiency (serum 25-hydroxyvitamin D 22.5 nmol/l [9 ng/ml]) was significantly reduced by 92% with FOSAVANCE (70 mg/2,800 IU) vs. alendronate-only (1% vs 13%, respectively). In this study, mean 25-hydroxyvitamin D levels in patients with vitamin D insufficiency at baseline (25-hydroxyvitamin D, 22.5 to 37.5 nmol/l [9 to <15 ng/ml]) increased from 30 nmol/l (12.1 ng/ml) to 40 nmol/l (15.9 ng/ml) at week 15 in the FOSAVANCE (70 mg/2,800 IU) group (n=75) and decreased from 30 nmol/l (12.0 ng/ml) at baseline to 26 nmol/l (10.4 ng/ml) at week 15 in the alendronate-only group (n=70). There were no differences in mean serum calcium, phosphate, or 24-hour urine calcium between treatment groups.
The effect of the lower dose of FOSAVANCE (alendronate 70 mg/vitamin D3 2,800 IU) plus an additional 2,800 IU Vitamin D3 for a total of 5,600 IU (the amount of vitamin D3 in the higher dose of FOSAVANCE) once weekly was demonstrated in a 24-week, extension study that enrolled 619 osteoporotic post-menopausal women. Patients in the Vitamin D3 2,800 group received FOSAVANCE (70 mg/2,800 IU) (n=299) and patients in the Vitamin D3 5,600 group received FOSAVANCE (70 mg/2,800 IU) plus an additional 2,800 IU vitamin D3 (n=309) once a week; additional vitamin D supplements were allowed. After 24-weeks of treatment, the mean serum 25-hydroxyvitamin D levels were significantly higher in the Vitamin D3 5,600 group (69 nmol/l [27.6 ng/ml]) than in the Vitamin D3 2,800 group (64 nmol/l [25.5 ng/ml]). The percentage of patients with vitamin D insufficiency was 5.4% in the Vitamin D3 2,800 group vs. 3.2% in the Vitamin D3 5,600 group through the 24-week extension. The percentage of patients with vitamin D deficiency was 0.3% in the Vitamin D3 2,800 group vs. zero in the Vitamin D3 5,600 group. There were no differences in mean serum calcium, phosphate, or 24-hour urine calcium between treatment groups. The percentage of patients with hypercalciuria at the end of the 24-week extension was not statistically different between treatment groups.
The therapeutic equivalence of alendronate once weekly 70 mg (n=519) and alendronate 10 mg daily (n=370) was demonstrated in a one-year multicentre study of post-menopausal women with osteoporosis. The mean increases from baseline in lumbar spine BMD at one year were 5.1% (95% CI: 4.8, 5.4%) in the 70 mg once-weekly group and 5.4% (95% CI: 5.0, 5.8%) in the 10 mg daily group. The mean BMD increases were 2.3% and 2.9% at the femoral neck and 2.9% and 3.1% at the total hip in the 70 mg once weekly and 10 mg daily groups, respectively. The two treatment groups were also similar with regard to BMD increases at other skeletal sites.
The effects of alendronate on bone mass and fracture incidence in post-menopausal women were examined in two initial efficacy studies of identical design (n=994) as well as in the Fracture Intervention Trial (FIT: n=6,459).
In the initial efficacy studies, the mean BMD increases with alendronate 10 mg/day relative to placebo at three years were 8.8%, 5.9% and 7.8% at the spine, femoral neck and trochanter, respectively. Total body BMD also increased significantly. There was a 48% reduction (alendronate 3.2% vs placebo 6.2%) in the proportion of patients treated with alendronate experiencing one or more vertebral fractures relative to those treated with placebo. In the two-year extension of these studies BMD at the spine and trochanter continued to increase and BMD at the femoral neck and total body were maintained.
FIT consisted of two placebo-controlled studies using alendronate daily (5 mg daily for two years and 10 mg daily for either one or two additional years):
In clinical studies, asymptomatic, mild and transient decreases in serum calcium and phosphate were observed in approximately 18% and 10%, respectively, of patients taking alendronate 10 mg/day versus approximately 12% and 3% of those taking placebo. However, the incidences of decreases in serum calcium to <8.0 mg/dl (2.0 mmol/l) and serum phosphate to 2.0 mg/dl (0.65 mmol/l) were similar in both treatment groups.
Alendronate sodium has been studied in a small number of patients with osteogenesis imperfecta under the age of 18 years. Results are insufficient to support the use of alendronate sodium in paediatric patients with osteogenesis imperfecta.
Relative to an intravenous reference dose, the oral mean bioavailability of alendronate in women was 0.64% for doses ranging from 5 to 70 mg when administered after an overnight fast and two hours before a standardised breakfast. Bioavailability was decreased similarly to an estimated 0.46% and 0.39% when alendronate was administered one hour or half an hour before a standardised breakfast. In osteoporosis studies, alendronate was effective when administered at least 30 minutes before the first food or beverage of the day.
The alendronate component in the FOSAVANCE (70 mg/2,800 IU) combination tablet and the FOSAVANCE (70 mg/5,600 IU) combination tablet is bioequivalent to the alendronate 70 mg tablet.
Bioavailability was negligible whether alendronate was administered with, or up to two hours after, a standardised breakfast. Concomitant administration of alendronate with coffee or orange juice reduced bioavailability by approximately 60%.
In healthy subjects, oral prednisone (20 mg three times daily for five days) did not produce a clinically meaningful change in oral bioavailability of alendronate (a mean increase ranging from 20% to 44%).
Studies in rats show that alendronate transiently distributes to soft tissues following 1 mg/kg intravenous administration but is then rapidly redistributed to bone or excreted in the urine. The mean steady-state volume of distribution, exclusive of bone, is at least 28 litres in humans. Concentrations of alendronate in plasma following therapeutic oral doses are too low for analytical detection (<5 ng/ml). Protein binding in human plasma is approximately 78%.
There is no evidence that alendronate is metabolised in animals or humans.
Following a single intravenous dose of [14C]alendronate, approximately 50% of the radioactivity was excreted in the urine within 72 hours and little or no radioactivity was recovered in the faeces. Following a single 10 mg intravenous dose, the renal clearance of alendronate was 71 ml/min, and systemic clearance did not exceed 200 ml/min. Plasma concentrations fell by more than 95% within six hours following intravenous administration. The terminal half-life in humans is estimated to exceed ten years, reflecting release of alendronate from the skeleton. Alendronate is not excreted through the acidic or basic transport systems of the kidney in rats, and thus it is not anticipated to interfere with the excretion of other medicinal products by those systems in humans.
In healthy adult subjects (males and females), following administration of FOSAVANCE 70 mg/2,800 IU tablets after an overnight fast and two hours before a meal, the mean area under the serum-concentration-time curve (AUC0-120hrs) for vitamin D3 (unadjusted for endogenous vitamin D3 levels) was 296.4 nghr/ml. The mean maximal serum concentration (Cmax) of vitamin D3 was 5.9 ng/ml, and the median time to maximal serum concentration (Tmax) was 12 hours. The bioavailability of the 2,800 IU vitamin D3 in FOSAVANCE is similar to 2,800 IU vitamin D3 administered alone.
In healthy adult subjects (males and females), following administration of FOSAVANCE 70 mg/5,600 IU after an overnight fast and two hours before a meal, the mean area under the serumconcentration-time curve (AUC0-80hrs) for vitamin D3 (unadjusted for endogenous vitamin D3 levels) was 490.2 nghr/ml. The mean maximal serum concentration (Cmax) of vitamin D3 was 12.2 ng/ml and the median time to maximal serum concentration (Tmax) was 10.6 hours. The bioavailability of the 5,600 IU vitamin D3 in FOSAVANCE is similar to 5,600 IU vitamin D3 administered alone.
Following absorption, vitamin D3 enters the blood as part of chylomicrons. Vitamin D3 is rapidly distributed mostly to the liver where it undergoes metabolism to 25-hydroxyvitamin D3, the major storage form. Lesser amounts are distributed to adipose and muscle tissue and stored as vitamin D3 at these sites for later release into the circulation. Circulating vitamin D3 is bound to vitamin D-binding protein.
Vitamin D3 is rapidly metabolised by hydroxylation in the liver to 25-hydroxyvitamin D3, and subsequently metabolised in the kidney to 1,25-dihydroxyvitamin D3, which represents the biologically active form. Further hydroxylation occurs prior to elimination. A small percentage of vitamin D3 undergoes glucuronidation prior to elimination.
When radioactive vitamin D3 was administered to healthy subjects, the mean urinary excretion of radioactivity after 48 hours was 2.4%, and the mean faecal excretion of radioactivity after 4 days was 4.9%. In both cases, the excreted radioactivity was almost exclusively as metabolites of the parent. The mean half-life of vitamin D3 in the serum following an oral dose of FOSAVANCE (70 mg/2,800 IU) is approximately 24 hours.
Preclinical studies show that alendronate that is not deposited in bone is rapidly excreted in the urine. No evidence of saturation of bone uptake was found after chronic dosing with cumulative intravenous doses up to 35 mg/kg in animals. Although no clinical information is available, it is likely that, as in animals, elimination of alendronate via the kidney will be reduced in patients with impaired renal function. Therefore, somewhat greater accumulation of alendronate in bone might be expected in patients with impaired renal function (see section 4.2).
Non-clinical studies with the combination of alendronate and colecalciferol have not been conducted.
Non-clinical data reveal no special hazard for humans based on conventional studies of safety pharmacology, repeated dose toxicity, genotoxicity and carcinogenic potential. Studies in rats have shown that treatment with alendronate during pregnancy was associated with dystocia in dams during parturition which was related to hypocalcaemia. In studies, rats given high doses showed an increased incidence of incomplete foetal ossification. The relevance to humans is unknown.
At doses far higher than the human therapeutic range, reproductive toxicity has been observed in animal studies.
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