ACTONEL
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ACTONEL (ACTONEL).
Bisphosphonate that inhibits osteoclast-mediated bone resorption by binding to hydroxyapatite in bone and interfering with osteoclast activity.
| Metabolism | Not metabolized; excreted unchanged in urine. |
| Excretion | Renal: 50-60% unchanged via glomerular filtration and active tubular secretion; Fecal: minor, biliary excretion negligible. |
| Half-life | Terminal elimination half-life: 1.5-2 hours (short for bisphosphonates due to rapid renal clearance); however, bone retention half-life is prolonged (>1 year) due to binding to hydroxyapatite. |
| Protein binding | ~24% bound to plasma proteins (primarily albumin). |
| Volume of Distribution | Vd: 0.5-1 L/kg, indicating distribution primarily into bone and extracellular fluid. |
| Bioavailability | Oral: 0.5-1% under fasting conditions (low due to poor intestinal absorption and high first-pass effect); reduced by 60-90% with food or calcium-containing beverages. |
| Onset of Action | Oral: 1-2 months (reduction in bone turnover markers); IV: not applicable (oral only). |
| Duration of Action | Duration of clinical effect: 3-6 months after single dose due to prolonged bone binding; requires weekly dosing for sustained effect. |
| Action Class | Bone resorption inhibitor -Bisphosphonates |
| Brand Substitutes | Fossical 35mg Tablet, Bone C Fos 35mg Tablet, Risoweek 35mg Tablet, Osteo Plus 35 Tablet, Risofos 35 Tablet |
35 mg orally once weekly or 5 mg orally once daily for osteoporosis; also 30 mg orally once weekly for Paget disease.
| Dosage form | TABLET |
| Renal impairment | Contraindicated if CrCl <30 mL/min. If CrCl 30-49 mL/min, no adjustment needed. If CrCl <30 mL/min, do not use. |
| Liver impairment | No dose adjustment required for mild to moderate hepatic impairment. Not studied in severe hepatic impairment (Child-Pugh C); use caution. |
| Pediatric use | Safety and efficacy not established in pediatric patients. Not recommended for use in children. |
| Geriatric use | No dose adjustment based on age alone. Monitor renal function. Ensure adequate calcium and vitamin D intake. Same dosing as adults. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ACTONEL (ACTONEL).
| Breastfeeding | Unknown if excreted in human milk. M/P ratio not established. Caution advised; consider alternative treatments during breastfeeding. |
| Teratogenic Risk | Pregnancy Category C. No adequate studies in pregnant women. In animal studies, bisphosphonates cause fetal skeletal abnormalities at high doses. Risk cannot be ruled out; use only if clearly needed. First trimester: potential for skeletal effects; second and third trimesters: risk of fetal hypocalcemia and skeletal retardation. Discontinue if pregnancy occurs. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Hypocalcemia","Inability to stand or sit upright for at least 30 minutes","Severe renal impairment (CrCl <30 mL/min)","Hypersensitivity to risedronate or any component"]
| Precautions | ["Hypocalcemia must be corrected before therapy","Esophageal irritation and potential for esophageal cancer","Renal impairment (creatinine clearance <30 mL/min) requires dose adjustment or avoidance","Osteonecrosis of the jaw (usually with cancer treatments)","Atypical femur fractures with long-term use","Musculoskeletal pain"] |
| Food/Dietary | Calcium, magnesium, iron, and aluminum (e.g., antacids) bind risedronate and reduce absorption. Separate by at least 30 minutes after taking risedronate. Avoid mineral water, dairy products, and calcium-fortified juices within 30 minutes of dosing. |
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| Fetal Monitoring |
| Monitor serum calcium, phosphate, and magnesium. Assess renal function. Consider fetal ultrasound if exposed during pregnancy. |
| Fertility Effects | No human data; animal studies show no significant effects on fertility at therapeutic doses. |
| Clinical Pearls | Actonel (risedronate) is a bisphosphonate for osteoporosis and Paget's disease. Administer on an empty stomach with plain water (not mineral water) at least 30 minutes before the first food, beverage, or other medication. Avoid in CrCl <30 mL/min. Monitor for hypocalcemia before treatment. Counsel on atypical femur fractures and osteonecrosis of the jaw (ONJ), especially with dental procedures. |
| Patient Advice | Take Actonel first thing in the morning with a full glass of plain water (6-8 oz) at least 30 minutes before any food, drink, or other medicine. · Do not lie down for at least 30 minutes after taking to reduce risk of esophageal irritation. · Avoid mineral water, coffee, tea, juice, or calcium-rich beverages as they can reduce absorption. · Report severe bone, joint, or muscle pain; jaw pain or numbness; or signs of hypocalcemia (muscle cramps, tingling). · Maintain adequate calcium and vitamin D intake as directed by your doctor. · If you miss a dose, skip it and resume next morning; do not take two doses on the same day. |