Usage
- Alendronic acid is primarily prescribed for the treatment and prevention of osteoporosis in postmenopausal women. It is also used in men for the treatment of osteoporosis. Additionally, it’s indicated for the treatment of glucocorticoid-induced osteoporosis and Paget’s disease of bone.
- Pharmacological Classification: Bisphosphonate
- Mechanism of Action: Alendronic acid inhibits osteoclast activity, reducing bone resorption and turnover. This allows osteoblasts (bone-forming cells) to work more effectively, leading to increased bone mineral density and reduced fracture risk.
Alternate Names
- Alendronate sodium (salt form)
- Brand Names: Fosamax, Binosto
How It Works
- Pharmacodynamics: Alendronic acid binds to hydroxyapatite crystals on bone surfaces, inhibiting osteoclast activity. This reduces bone resorption and turnover, leading to a net increase in bone mineral density.
- Pharmacokinetics:
- Absorption: Oral absorption is low (less than 1%) and further reduced by food and certain medications.
- Distribution: Distributes rapidly to bone surfaces.
- Metabolism: Not metabolized.
- Elimination: Primarily excreted unchanged in urine; a small portion is taken up by bone. The elimination half-life is estimated to be more than 10 years due to its slow release from the skeletal system.
- Mode of Action: Alendronic acid inhibits farnesyl pyrophosphate synthase, an enzyme essential for osteoclast function and survival. This disruption of the mevalonate pathway in osteoclasts leads to their apoptosis (programmed cell death), thus decreasing bone resorption.
Dosage
Standard Dosage
Adults:
- Osteoporosis (Treatment): 70 mg orally once weekly OR 10 mg orally once daily.
- Osteoporosis (Prevention): 35 mg orally once weekly OR 5 mg orally once daily (postmenopausal women).
- Glucocorticoid-Induced Osteoporosis: 5 mg orally once daily, OR 10 mg orally once daily in postmenopausal women not receiving estrogen.
- Paget’s Disease: 40 mg orally once daily for 6 months.
Children:
- Alendronate is not recommended for use in children under 18 years old due to insufficient data on safety and efficacy.
Special Cases:
- Elderly Patients: No dosage adjustment is necessary.
- Patients with Renal Impairment: No dosage adjustment is needed for creatinine clearance greater than 35 mL/min. Not recommended for patients with creatinine clearance less than 35 mL/min.
- Patients with Hepatic Dysfunction: No dosage adjustment is necessary.
Clinical Use Cases The provided sources do not mention clinical use cases for alendronic acid with Intubation, Surgical Procedures, Mechanical Ventilation, Intensive Care Unit (ICU) Use, or Emergency Situations.
Dosage Adjustments Dose adjustments may be necessary for patients with severe renal impairment (creatinine clearance < 35 mL/min). In these cases, alendronate is generally not recommended.
Side Effects
Common Side Effects
- Abdominal pain
- Acid regurgitation
- Constipation
- Diarrhea
- Dyspepsia
- Esophageal ulcer
- Flatulence
- Headache
- Musculoskeletal pain
Rare but Serious Side Effects
- Atypical femoral fractures
- Esophageal cancer
- Osteonecrosis of the jaw
Long-Term Effects
- Potential for atypical femoral fractures and osteonecrosis of the jaw with prolonged use.
Adverse Drug Reactions (ADR)
- Esophageal reactions (esophagitis, erosions, ulcers)
- Musculoskeletal pain (severe and incapacitating)
- Hypocalcemia
- Osteonecrosis of the jaw
- Atypical femur fractures
- Ocular inflammation (uveitis, scleritis)
Contraindications
- Hypersensitivity to alendronic acid or any component of the formulation.
- Hypocalcemia
- Abnormalities of the esophagus which delay esophageal emptying (e.g., stricture, achalasia).
- Inability to stand or sit upright for at least 30 minutes.
Drug Interactions
- Antacids, calcium supplements, and other medications containing multivalent cations (e.g., iron, magnesium) interfere with alendronate absorption and should be taken at least 2 hours apart.
- Nonsteroidal anti-inflammatory drugs (NSAIDs) may increase the risk of gastrointestinal irritation.
- Certain medications can affect calcium levels and interact with alendronate.
Pregnancy and Breastfeeding
- Pregnancy: Alendronate is generally avoided during pregnancy due to limited data on safety for the developing fetus.
- Breastfeeding: Alendronate is excreted in breast milk in small amounts. The risk to the breastfed infant is considered low, but caution is advised.
Drug Profile Summary
- Mechanism of Action: Inhibits osteoclast-mediated bone resorption.
- Side Effects: Abdominal pain, musculoskeletal pain, esophageal irritation, osteonecrosis of the jaw, atypical femoral fractures.
- Contraindications: Hypocalcemia, esophageal abnormalities, inability to sit upright for 30 minutes, hypersensitivity.
- Drug Interactions: Antacids, calcium supplements, NSAIDs.
- Pregnancy & Breastfeeding: Use with caution. Generally avoided during pregnancy.
- Dosage: Variable depending on indication; 70 mg once weekly or 10 mg once daily for osteoporosis treatment.
- Monitoring Parameters: Bone mineral density, serum calcium and phosphate, renal function.
Popular Combinations
- Alendronate is often combined with vitamin D (colecalciferol) to enhance calcium absorption and bone health. Calcium supplements may also be prescribed if dietary intake is insufficient.
Precautions
- General Precautions: Ensure adequate calcium and vitamin D intake. Perform dental examination prior to treatment and encourage good oral hygiene.
- Specific Populations: As described above.
- Lifestyle Considerations: Advise patients to avoid smoking and excessive alcohol consumption.
FAQs (Frequently Asked Questions)
Q1: What is the recommended dosage for Alendronic Acid?
A: The dosage depends on the indication. For osteoporosis treatment in adults, it’s 70 mg once weekly or 10 mg once daily. For prevention of osteoporosis in postmenopausal women, it’s 35 mg once weekly or 5 mg once daily.
Q2: How should Alendronic Acid be taken?
A: Take alendronate first thing in the morning, at least 30 minutes before any food, beverage, or other medication, with a full glass of plain water (6-8 ounces). Remain upright (sitting or standing) for at least 30 minutes after taking the medication.
Q3: What are the most common side effects of Alendronic Acid?
A: Common side effects include abdominal pain, acid regurgitation, musculoskeletal pain, nausea, and difficulty swallowing.
Q4: What are the serious side effects of Alendronic Acid?
A: Rare but serious side effects include osteonecrosis of the jaw, atypical femur fractures, and severe esophageal reactions.
Q5: Who should not take Alendronic Acid?
A: Patients with hypocalcemia, esophageal abnormalities, inability to sit upright for 30 minutes, or hypersensitivity to alendronate should not take this medication.
Q6: Can Alendronic Acid be taken during pregnancy or breastfeeding?
A: Alendronate should generally be avoided during pregnancy. It is excreted in breast milk in small amounts. Consult with a physician regarding use during breastfeeding.
Q7: What are the drug interactions with Alendronic Acid?
A: Antacids, calcium supplements, iron supplements, and certain other medications can interfere with alendronate absorption.
Q8: How long should Alendronic Acid be taken?
A: The optimal duration of therapy varies depending on individual risk factors. Re-evaluation of the need for continued treatment is recommended, particularly after 5 years of use.
Q9: What should I do if I miss a dose of Alendronic Acid?
A: If you miss a weekly dose, take it the morning after you remember. Do not take two doses on the same day. Return to your regular weekly schedule on your chosen day. If you miss a daily dose, skip the missed dose and take your next dose as scheduled.
Q10: What are some important precautions to take while on Alendronic Acid?
A: Maintain adequate calcium and vitamin D intake. Have regular dental check-ups and inform your dentist about alendronate use. Report any unusual bone pain, especially in the thigh or groin area.
