Risedronic acid (risedronate)
Bisphosphonates
BisphosphonatesPregnancy: avoid
Not used in pregnancy; stopped if pregnancy is recognised, and stored drug in bone is a theoretical risk for the fetal skeleton.
An oral bisphosphonate for osteoporosis and Paget disease, taken under the same strict rules as alendronate to protect the oesophagus.
Also called: Risedronate sodium
Quick facts
- Group
- Bisphosphonates
- Target
- Farnesyl pyrophosphate synthase (FPPS), an enzyme of the mevalonate pathway in osteoclasts
- Used for
- Treatment and prevention · Osteoporosis in men
- Key effects
- Nausea · Diarrhoea or constipation · Headache
- Monitor
- Calcium and vitamin D before starting · Dental health
- ATC
- M05BA07
No doses: the clinician sets them by the current guideline.
Mechanism of action
The figure shows risedronate itself in the active site of human farnesyl pyrophosphate synthase, with magnesium ions.
Risedronate is a pyridinyl (nitrogen-containing) bisphosphonate. It binds hydroxyapatite and, once taken up by osteoclasts, inhibits farnesyl pyrophosphate synthase. Osteoclast activity and bone turnover fall, bone density rises and fractures become less frequent.
- Risedronate binds bone mineral at resorption sites
- Osteoclasts take it up as they resorb bone
- It blocks farnesyl pyrophosphate synthase
- Bone turnover falls and density rises
Indications
- Treatment and prevention of postmenopausal osteoporosis Osteoporosis →
- Osteoporosis in men and glucocorticoid-induced osteoporosis
- Paget disease of bone Paget disease of bone →
Adverse effects
Common
- Nausea, abdominal pain, dyspepsia
- Diarrhoea or constipation
- Back and joint pain
- Headache
Contraindications
- Oesophageal abnormalities that delay emptying, such as stricture or achalasia
- Inability to stand or sit upright for at least 30 minutes
- Hypocalcaemia
- Hypersensitivity to risedronate
- Not recommended with severe kidney impairment
Key interactions
- Calcium, antacids, iron and other divalent cations
- Lower risedronate absorption; they are taken at a different time
- Food and any drink other than plain water
- Much lower absorption; the immediate-release tablet is taken before food or drink
What is monitored
- Calcium and vitamin D before starting
- Kidney function
- Bone density and fracture risk over time
- Swallowing symptoms and heartburn
- Dental health; thigh or groin pain
Administration and safety
- Immediate-release tablets: first thing in the morning, before any food or drink, with plain water
- The delayed-release form is the exception: it is taken right after breakfast
- Swallowed whole, not chewed or sucked; the person stays upright for at least 30 minutes
- Calcium, antacids and other oral medicines are separated from the dose
Pregnancy and breastfeeding
Not used in pregnancy; stopped if pregnancy is recognised, and stored drug in bone is a theoretical risk for the fetal skeleton.
Nursing care
- Confirm which form is ordered (immediate or delayed release), because the timing with food is opposite
- Check that the person can stay upright
- Teach to report pain on swallowing, new heartburn or chest pain
- Review calcium and vitamin D intake and dental care
- Report thigh or groin pain
Pharmacokinetics
- Absorption
- Very low oral absorption, reduced further by food
- Metabolism
- Not metabolised; it neither induces nor inhibits CYP enzymes
- Elimination
- By the kidney; clearance falls with kidney impairment
Test yourself
Think of the answer, then tap the question to see it.
How does the timing of delayed-release risedronate differ from the usual tablets?
The usual tablets are taken before any food or drink in the morning; the delayed-release form is taken right after breakfast.
Why is risedronate avoided in severe kidney impairment?
It is cleared by the kidney, so the drug accumulates; the label does not recommend it below a low creatinine clearance.
Which bisphosphonate group does risedronate belong to, and what does it inhibit?
It is a pyridinyl, nitrogen-containing bisphosphonate that inhibits farnesyl pyrophosphate synthase in osteoclasts.
Connections
← Back to the class: Bisphosphonates
Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.
Sources: Risedronate: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); DailyMed - RISEDRONATE SODIUM tablet, film coated (DailyMed (U.S. National Library of Medicine), 2026); ATCDDD - ATC/DDD Index (WHO Collaborating Centre for Drug Statistics Methodology, 2026).
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Representative model, for educational purposes only.