Fosamax 35 mg Tablets

Brand Name

The medication is marketed under the brand name Fosamax, a well-established label in the field of bone health and metabolic disorder management.

International Nonproprietary Name (INN)

The active ingredient in this product is identified globally as alendronate sodium, a name standardized for consistency across international pharmacological practices.

Form of Release

Fosamax is available as oral tablets, designed for convenient administration. These tablets come in strengths of 5 mg, 10 mg, 35 mg, 40 mg, and 70 mg, typically packaged in blister packs to ensure proper dosing and storage.

Composition

Each tablet of Fosamax contains alendronate sodium as the primary active substance, with dosages varying by strength (5 mg, 10 mg, 35 mg, 40 mg, or 70 mg, equivalent to alendronic acid). The formulation includes several inactive ingredients, such as microcrystalline cellulose, which provides structural support, and lactose anhydrous, acting as a filler. Additional excipients like magnesium stearate serve as lubricants to aid in tablet production, while croscarmellose sodium facilitates disintegration. Small amounts of other stabilizers may be present to maintain the drug’s integrity and effectiveness throughout its shelf life.

Pharmacologic Properties

Pharmacodynamics

Fosamax belongs to the bisphosphonate class, exerting its therapeutic effects by inhibiting osteoclast-mediated bone resorption. It binds preferentially to hydroxyapatite in bone tissue, particularly at sites of active remodeling, where it disrupts the mevalonate pathway in osteoclasts. This disruption impairs the prenylation of proteins essential for osteoclast function, reducing their activity and lifespan, which in turn decreases bone breakdown. The result is a net increase in bone mineral density (BMD) and a reduction in fracture risk, particularly in trabecular and cortical bone.

The medication does not interfere with bone formation directly, allowing osteoblasts to continue mineralization, though the overall remodeling rate slows. Clinical studies demonstrate its ability to increase BMD by 5–10% over several years in postmenopausal women, significantly lowering the incidence of vertebral and hip fractures. Its anti-resorptive action also stabilizes bone architecture, offering long-term skeletal protection. This targeted mechanism makes it a cornerstone in managing conditions characterized by excessive bone loss.

Pharmacokinetics

Following oral administration, Fosamax is poorly absorbed from the gastrointestinal tract, with bioavailability averaging less than 1% in a fasting state. Absorption drops further if taken with food or beverages other than water, necessitating strict administration guidelines. The drug distributes primarily to bone tissue, binding to hydroxyapatite, with minimal uptake in soft tissues, and exhibits plasma protein binding of about 78%.

Metabolism is negligible, as alendronate is not processed by cytochrome P450 enzymes or other hepatic pathways, remaining largely unchanged in the body. The half-life in bone is estimated at over 10 years due to its strong skeletal affinity, while the plasma half-life is short, around 1–2 hours. Elimination occurs primarily via the kidneys, with approximately 50% of the absorbed dose excreted unchanged in urine within 72 hours, and the remainder sequestered in bone for gradual release over time.

Indications for Use

Fosamax is prescribed primarily for the treatment and prevention of osteoporosis in postmenopausal women, where it increases bone density and reduces fracture risk. It is also indicated for osteoporosis in men, addressing age-related or steroid-induced bone loss. The medication is used to manage glucocorticoid-induced osteoporosis in patients on long-term corticosteroid therapy, helping maintain skeletal integrity under these conditions.

Another key indication is the treatment of Paget’s disease of bone, where it normalizes excessive bone turnover, alleviating pain and reducing deformity risk. It may be employed in specific cases of hypercalcemia associated with malignancy, though this is less common and typically involves higher doses. These applications underscore its role in supporting bone health across diverse metabolic disorders.

Contraindications

Fosamax is contraindicated in patients with esophageal abnormalities, such as stricture or achalasia, that delay emptying, due to risks of irritation or ulceration. It is also prohibited in those unable to stand or sit upright for at least 30 minutes post-dose, as this position minimizes esophageal exposure. Hypersensitivity to alendronate or any tablet component, like lactose, precludes its use, with potential reactions ranging from mild rashes to severe allergic responses.

Severe renal impairment (creatinine clearance below 35 mL/min) is a strict limitation, given its renal excretion profile. Hypocalcemia must be corrected before initiation, as the drug may exacerbate low calcium levels. Use is restricted in individuals with active upper gastrointestinal issues, such as Barrett’s esophagus or severe reflux, due to potential exacerbation.

Method of Administration and Dosage

Administration Guidelines

The tablets should be taken orally, swallowed whole with a full glass of plain water (6–8 ounces) at least 30 minutes before the first food, beverage, or medication of the day. Patients must remain upright (standing or sitting) for at least 30 minutes post-dose to reduce esophageal irritation. Taking it with food, coffee, or juice severely impairs absorption and should be avoided.

Dosage for Adults and Children

For postmenopausal osteoporosis, the typical dose of Fosamax is 10 mg daily or 70 mg once weekly. Prevention in this group uses 5 mg daily or 35 mg weekly. Men with osteoporosis follow the 10 mg daily or 70 mg weekly regimen. Glucocorticoid-induced osteoporosis requires 5 mg daily, or 10 mg daily for postmenopausal women not on estrogen. Paget’s disease involves 40 mg daily for 6 months. Children are not typically prescribed this therapy, as safety and efficacy are unestablished in pediatric populations.

Dose Adjustment in Specific Conditions

In mild to moderate renal impairment (creatinine clearance 35–60 mL/min), no adjustment is needed, but severe impairment (below 35 mL/min) contraindicates use. Liver dysfunction does not require dose changes, as metabolism is minimal. Elderly patients or those with swallowing difficulties may need alternative formulations or therapies if the upright requirement is unfeasible. Calcium and vitamin D supplementation should accompany treatment to optimize efficacy.

Side Effects

Fosamax may cause a variety of side effects, though many patients tolerate it well with proper administration. Common reactions include gastrointestinal discomfort, such as abdominal pain, dyspepsia, or acid reflux, often linked to esophageal irritation if dosing instructions are not followed. Musculoskeletal pain, including bone, joint, or muscle discomfort, is also reported, typically mild and transient.

Less frequent effects include headache, nausea, or flatulence, which usually resolve with continued use. Rare but serious issues, such as osteonecrosis of the jaw (ONJ), atypical femoral fractures, or severe esophageal ulceration, require immediate medical attention, particularly in long-term users or those with predisposing factors. Hypocalcemia or rash may occur infrequently, warranting monitoring. Adherence to dosing guidelines minimizes these risks significantly.

Overdose

Symptoms of Overdose

Excessive intake of Fosamax may lead to hypocalcemia, hypophosphatemia, and upper gastrointestinal distress, such as severe nausea, vomiting, or esophageal pain. These effects stem from exaggerated pharmacological action and poor absorption, with no acute life-threatening profile established. Symptoms typically reflect electrolyte imbalance or mucosal irritation.

First Aid Measures

In case of overdose, medical consultation is recommended, with immediate administration of milk or antacids to bind the drug and reduce absorption. Patients should avoid lying down to minimize esophageal damage and seek care for electrolyte correction if needed. Dialysis is ineffective due to bone binding, so supportive measures focus on symptom relief until stability returns.

Drug Interactions

Effects on Other Medications

Fosamax has minimal impact on cytochrome P450 enzymes, as it is not metabolized hepatically, reducing pharmacokinetic interactions. However, it can chelate with calcium-containing drugs, antacids, or multivitamins, impairing its own absorption if taken concurrently. Nonsteroidal anti-inflammatory drugs (NSAIDs) may increase gastrointestinal irritation risk when co-administered, though systemic effects remain unchanged.

Drugs like proton pump inhibitors or H2 blockers do not directly interact but may exacerbate underlying esophageal issues. Patients should space administration of other medications by at least 30 minutes post-dose to avoid interference.

Compatibility with Alcohol and Food

Moderate alcohol use does not affect the drug’s efficacy, though excessive consumption may worsen gastrointestinal tolerance. Food, beverages (except plain water), or calcium-rich supplements severely reduce absorption if taken within 30 minutes, necessitating strict fasting adherence pre-dose for optimal effect.

Special Precautions

Use During Pregnancy and Breastfeeding

Fosamax is not recommended in pregnancy, as animal studies suggest potential fetal skeletal effects, and human data are lacking. It falls under Category C, reserved for cases where benefits outweigh risks, though such scenarios are rare. During breastfeeding, it may pass into milk in small amounts and incorporate into infant bone, so use is discouraged unless essential, with alternatives preferred.

Women of childbearing age should ensure non-pregnant status before starting and use contraception during therapy to avoid unintended exposure.

Impact on Driving and Operating Machinery

The medication does not typically impair cognitive or motor functions, making it safe for most patients to drive or operate machinery. Rare musculoskeletal pain or dizziness may suggest caution in affected individuals until symptoms subside, particularly early in treatment.

Considerations for Elderly and Pediatric Populations

Elderly patients, a primary group for osteoporosis treatment, tolerate Fosamax well, with no significant efficacy differences, though renal function monitoring is key. Children are not prescribed this therapy, as safety and efficacy remain untested in pediatric populations, limiting its use to adults.