Names and pronunciation
(meth-il-nal-trex′one) Relistor
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Drug reference
(meth-il-nal-trex′one) Relistor
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Func. class.: GI agent
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Chem. class.: Opioid antagonist
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ACTION: Peripheral μ-opioid recep- tor antagonist that reduces constipation associated with opiate agonists
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USES: Treatment of opioid-induced constipation in patients with advanced ill- ness who are receiving palliative care when response to laxative therapy has been insuf- ficient; treatment of opioid-induced consti- pation in chronic noncancer pain
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CONTRAINDICATIONS: Hyper- sensitivity, GI obstruction, IV route, eclampsia, elective induction of labor, hypertension, preeclampsia, pregnancy Precautions: Pregnancy, breastfeeding, children, geriatric patients, renal dis- ease, diarrhea, driving, operating machinery, neoplastic disease, Crohn’s disease, peptic ulcer, ulcerative colitis
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SIDE EFFECTS CNS: Dizziness GI: Nausea, vomiting, diarrhea, flatu- lence, abdominal pain, GI perforation
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DOSAGE AND ROUTES Opiate-agonist–induced constipation • Adult >114 kg: SUBCUT 0.15 mg/kg every other day prn, max 0.15 mg/kg/24 hours • Adult 62-114 kg: SUBCUT 12 mg every other day prn, max 12 mg/24 hr • Adult 38-<62 kg: SUBCUT 8 mg every other day prn, max 8 mg/24 hr • Adult <38 kg: SUBCUT 0.15 mg/kg every other day prn, max 0.15 mg/kg/24 hr Renal dose • Adult: SUBCUT CCr <60 mL/min, re- duce normal adult dose by 50%; PO 150 mg/day
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Available forms: Sol for inj 12 mg/0.6 mL (single-use vials), 8 mg/0.4 mL (pre- filled syringes); tab 150 mg
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Administer: PO route • Take on empty stomach at least 30 min before first meal of the day SUBCUT route Do not give IV; IV dosing for urinary re- tention investigational • Store at 59°F-86°F (15°C-30°C); do not freeze • Store away from light • Inspect sol before use; should be clear, colorless to pale yellow aqueous sol; do not use if particulate matter or discoloration is present • Withdraw needed amount of sol into sterile syringe; syringe may be kept at room temperature for ≤24 hr; immedi- ately discard any unused portion in vial; no preservatives are present • Administer into upper arm, abdomen, or thigh ≤1×/24 hr; rotate inj sites; do not inject in same spot each time; do not inject into areas where skin is tender, bruised, red, or hard; avoid areas with scars or stretch marks • If using with retractable needle, slowly push down on plunger past resistance point until the syringe is empty and click is heard PO route • Give with water on empty stomach 30 min before morning meal
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Assess: • Serum creatinine, BUN, baseline and periodically • Opioid-induced constipation: stool characteristics, bowel sounds during treatment • Pain: monitor characteristics of pain; this product does not affect analgesics • Beers: avoid in older adults unless safer alternatives are unavailable; may cause ataxia, impaired psychomotor function M • Pregnancy/breastfeeding: avoid use in pregnancy, withdrawal in fetus may occur; do not breastfeed
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Evaluate: • Therapeutic response: decreasing constipation
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CLINICAL CONSIDERATIONS
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Patient and caregiver information: • That, after 30 min, to remain near toilet facilities because bowel relaxation occurs; not to use more than 1 dose in 24 hr • To notify prescriber of abdominal pain, continuous or severe diarrhea, nausea, vomiting • Pregnancy/breastfeeding: to avoid use in pregnancy unless absolutely neces- sary; to avoid in breastfeeding • To notify prescriber before taking all other OTC, prescription, or herbal products • Not to drive or perform other hazard- ous activities until response is known; dizziness may occur • To continue other products for consti- pation unless directed by prescriber not to • Opioid withdrawal: to report severe diarrhea, abdominal pain, chills
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PHARMACOKINETICS Half-life 8 hr, protein binding 11%- 15.3%; dose adjustment is required for patients with CCr <60 mL/min SUBCUT: Peak 30 min
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• Adult >114 kg: SUBCUT 0.15 mg/kg every other day prn, max 0.15 mg/kg/24 hours
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• Adult 62-114 kg: SUBCUT 12 mg every other day prn, max 12 mg/24 hr
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• Adult 38-<62 kg: SUBCUT 8 mg every other day prn, max 8 mg/24 hr
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• Adult <38 kg: SUBCUT 0.15 mg/kg every other day prn, max 0.15 mg/kg/24 hr Renal dose
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• Adult: SUBCUT CCr <60 mL/min, re- duce normal adult dose by 50%; PO 150 mg/day
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