Risedronic acid

Oral
Postmenopausal osteoporosis
Adult: As conventional tab: Treatment and prophylaxis: 5 mg once daily. Alternatively, 35 mg once weekly, or 75 mg taken on 2 consecutive days per month, or 150 mg once monthly. As delayed-release tab: Treatment: 35 mg once weekly. Re-evaluate the need for continued therapy periodically according to individual benefits and potential risks.
Renal impairment:

CrCl (ml/min)	Dosage Recommendation
<30	Contraindicated.

Oral
Corticosteroid-induced osteoporosis
Adult: Treatment and prophylaxis in patients who are receiving chronic systemic corticosteroid therapy (prednisone ≥7.5 mg daily or equivalent): As conventional tab: 5 mg once daily. Re-evaluate the need for continued therapy periodically according to individual benefits and potential risks.
Renal impairment:

CrCl (ml/min)	Dosage Recommendation
<30	Contraindicated.

Oral
Paget's disease of bone
Adult: As conventional tab: 30 mg once daily for 2 months; may be repeated if necessary after at least 2 months post-treatment observation period. For retreatment, the same dose and duration of therapy may be given.
Renal impairment:

CrCl (ml/min)	Dosage Recommendation
<30	Contraindicated.

Oral
Osteoporosis in men
Adult: As conventional tab: 35 mg once weekly. Re-evaluate the need for continued therapy periodically according to individual benefits and potential risks.
Renal impairment:

CrCl (ml/min)	Dosage Recommendation
<30	Contraindicated.

Hypocalcaemia, abnormalities of the oesophagus which may delay emptying (e.g. stricture, achalasia); inability to stand or sit upright for at least 30 minutes. Severe renal impairment (CrCl <30 mL/minute). Pregnancy and lactation.

Patient with active upper gastrointestinal disease (e.g. dysphagia, known Barrett's oesophagus or other oesophageal diseases, gastritis, duodenitis, ulcers), risk factors for developing osteonecrosis of the jaw (e.g. cancer, anaemia, coagulopathy, ill-fitting dentures, poor oral hygiene, invasive dental procedures, history of dental or periodontal disease) or external auditory canal (e.g. infection, trauma, steroid use); other disturbances affecting bone and mineral metabolism (e.g. hypovitaminosis D, parathyroid dysfunction). Mild to moderate renal impairment. Patient Counselling Ensure adequate Ca and vitamin D intake; supplements may be considered if dietary intake is insufficient. Monitoring Parameters Correct hypocalcaemia or other disturbances of bone and mineral metabolism, and evaluate sex steroid hormonal status prior to therapy initiation. Monitor serum Ca and 25-hydroxyvitamin D; specific biochemical markers of bone turnover. Osteoporosis: Evaluate serial bone mineral density (BMD) at baseline and every 1-3 years during treatment, then every 2-4 years during a drug holiday. In patients on combined risedronate and glucocorticoid therapy: Assess BMD at the start of glucocorticoid therapy, after 6-12 months, then every 2-3 years if patient continues to have significant osteoporosis risk. Monitor height and weight yearly; signs of chronic back pain. Perform dental examination before treatment in patients at risk of osteonecrosis of the jaw. Paget's disease: Monitor serum total alkaline phosphatase at 6-12 weeks and potentially at 6 months, then at approx 6-12-month intervals following treatment completion.

Significant: Atypical subtrochanteric and diaphyseal femoral fractures (prolonged use); severe bone, joint or muscle pain; upper gastrointestinal mucosa irritation (e.g. dysphagia, oesophagitis, oesophageal or gastric ulcers, oesophageal erosions or stricture), ocular effects (e.g. iritis, uveitis), hypocalcaemia, osteonecrosis of the jaw and external auditory canal. Gastrointestinal disorders: Abdominal pain, constipation, diarrhoea, dyspepsia, nausea, vomiting. Infections and infestations: Infection. Investigations: Decreased serum phosphate levels (transient and mild). Musculoskeletal and connective tissue disorders: Back pain, pain in the extremity. Nervous system disorders: Headache. Renal and urinary disorders: Urinary tract infection. Skin and subcutaneous tissue disorders: Rash; bullous skin reactions, Stevens-Johnson syndrome, toxic epidermal necrolysis. Vascular disorders: Hypertension.

Symptoms: Hypocalcaemia and hypophosphataemia. Management: May give milk or antacids to reduce absorption. Gastric lavage may be considered in cases of substantial overdose. May administer IV Ca to relieve signs and symptoms of hypocalcaemia.

Decreased absorption with antacids, mineral supplements or other medicinal products containing polyvalent cations (e.g. Ca, Al, Fe, Mg). Delayed-release tab: Agents that elevate stomach pH (e.g. histamine 2 [H₂] receptor blockers, PPIs) may cause rapid drug release which may increase plasma risedronic acid concentrations.

Reduced absorption with food and drinks including mineral water.

May interfere with diagnostic imaging agents (e.g. technetium-99m-diphosphonate) in bone scans.

Risedronic acid, a pyridinyl bisphosphonate analogue, binds to hydroxyapatite and inhibits bone resorption via actions on osteoclast or osteoclast precursors. It reduces the increased rate of bone turnover while osteoblast activity and bone mineralisation are preserved.
Absorption: Poorly absorbed from the gastrointestinal tract. Decreased absorption when administered with food, or products containing Ca or other polyvalent cations. Bioavailability: Approx 0.54-0.75%. Time to peak plasma concentration: Approx 1 hour (conventional tab); approx 3 hours (delayed-release tab).
Distribution: Volume of distribution: Approx 6.3-13.8 L/kg. Plasma protein binding: Approx 24%.
Metabolism: Not metabolised.
Excretion: Via urine (approx half of the absorbed dose); faeces (unabsorbed drug). Terminal elimination half-life: 480-561 hours.

Oral: Store between 20-25°C.

Agents Affecting Bone Metabolism

M05BA07 - risedronic acid ; Belongs to the class of bisphosphonates. Used in the treatment of bone diseases.