AVINZA
Clinical safety rating
cautionComprehensive clinical and safety monograph for AVINZA (AVINZA).
AVINZA (morphine sulfate) is a full opioid agonist that binds to mu-opioid receptors in the CNS, producing analgesia by altering pain perception and emotional response to pain.
| Metabolism | Primarily hepatic via glucuronidation by UGT2B7 to morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G); minor CYP2C9 involvement. |
| Excretion | Primarily renal (approximately 90% as morphine metabolites, mainly morphine-3-glucuronide and morphine-6-glucuronide); biliary/fecal excretion accounts for less than 10%. |
| Half-life | Terminal elimination half-life of morphine is approximately 1.5-2 hours; however, due to the extended-release formulation, the effective half-life is prolonged to about 9-11 hours, allowing once-daily dosing. |
| Protein binding | Approximately 30-40% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Approximately 3-4 L/kg, indicating extensive tissue distribution. |
| Bioavailability | Oral bioavailability of morphine is variable (approximately 20-40%) due to extensive first-pass metabolism; the extended-release formulation provides consistent absorption over 24 hours. |
| Onset of Action | Oral: Peak analgesic effect occurs at 4-6 hours after administration; initial effects may be seen within 30-60 minutes but full effect is delayed due to extended-release properties. |
| Duration of Action | Analgesic duration is approximately 24 hours with once-daily dosing; steady-state is achieved within 3-5 days. |
| Molecular Weight | 285.34 |
Oral, 30 mg once daily (q24h) for opioid-naïve patients; titrate based on response. Maximum daily dose 160 mg. Administer with food to minimize peak effects.
| Dosage form | CAPSULE, EXTENDED RELEASE |
| Renal impairment | For GFR 30-59 mL/min: initiate at 50% of usual dose and titrate carefully; GFR <30 mL/min: initiate at 25% of usual dose; avoid in severe renal impairment (GFR <15 mL/min). |
| Liver impairment | Child-Pugh Class A: initiate at 50% of usual dose; Class B: initiate at 25% of usual dose; Class C: avoid use. |
| Pediatric use | Not recommended in pediatric patients <18 years; safety and efficacy not established. For adolescent patients (≥18 kg), off-label use: 0.1-0.2 mg/kg/dose q4-6h PRN; extended-release formulations not intended for children. |
| Geriatric use | For patients ≥65 years: initiate at 50% of adult dose (15 mg once daily) and titrate cautiously due to increased sensitivity, reduced renal/hepatic function, and higher risk of respiratory depression. Consider lower starting doses and extended intervals. |
| 1st trimester | Not recommended due to risk of neural tube defects and congenital anomalies; use only if benefit outweighs risk. |
| 2nd trimester | May cause fetal dependence and withdrawal; use only if clearly needed. |
| 3rd trimester | Prolonged use may lead to neonatal opioid withdrawal syndrome; avoid near term. |
Clinical note
Comprehensive clinical and safety monograph for AVINZA (AVINZA).
| Placental transfer | Morphine crosses the placenta readily; fetal concentrations can be similar to maternal. |
| Breastfeeding | Avinza (morphine) is excreted in breast milk; monitor infant for respiratory depression and sedation; avoid use in breastfeeding mothers if possible. |
| Lactation Rating | L3 (Moderately Safe) - caution advised |
| Teratogenic Risk | First trimester: Limited human data; animal studies show no evidence of teratogenicity at clinically relevant doses. Second and third trimesters: Prolonged use may cause neonatal opioid withdrawal syndrome (NOWS) and respiratory depression at birth. Avoid chronic use near term. |
| Fetal Monitoring | Monitor maternal respiratory status, sedation level, and bowel function. Fetal monitoring for growth and well-being; assess for signs of NOWS in neonates post-delivery. Consider umbilical cord blood or meconium drug testing if indicated. |
| Fertility Effects | No established effect on fertility in humans. Animal studies show no impairment of fertility at therapeutic doses. Chronic opioid use may contribute to hormonal alterations (e.g., hypogonadism) that could affect fertility. |
■ FDA Black Box Warning
WARNING: ADDICTION, ABUSE, AND MISUSE; LIFE-THREATENING RESPIRATORY DEPRESSION; ACCIDENTAL INGESTION; NEONATAL OPIOID WITHDRAWAL SYNDROME; AND RISKS FROM CONCOMITANT USE WITH BENZODIAZEPINES OR OTHER CNS DEPRESSANTS.
| Serious Effects |
Hypersensitivity to morphine or any componentRespiratory depression (in unmonitored settings)Acute or severe bronchial asthmaParalytic ileusConcurrent use of MAOIs or within 14 days
| Precautions | Risk of life-threatening respiratory depression; addiction, abuse, and misuse; neonatal opioid withdrawal syndrome; interactions with CNS depressants; severe hypotension; gastrointestinal obstruction; seizure risk; impaired mental or physical abilities. |
| Food/Dietary | Avoid alcohol and alcohol-containing products (e.g., some mouthwashes, extracts) due to risk of dose dumping. Grapefruit juice may increase morphine bioavailability; limit intake. High-fat meals may delay absorption but not significantly alter overall exposure. |
| Clinical Pearls | AVINZA is an extended-release morphine formulation using the SODAS (Spheroidal Oral Drug Absorption System) technology, consisting of immediate-release and sustained-release beads. It must be taken whole; crushing or chewing can lead to rapid release and fatal overdose. Do not use in opioid-naïve patients; initiate with lower strengths if converting from other opioids. Monitor for signs of serotonin syndrome when co-administered with serotonergic drugs. Avoid alcohol consumption; ethanol can cause dose dumping. |
| Patient Advice | Take this medication exactly as prescribed; do not crush, chew, or break the capsules. · Swallow the capsules whole; if you have trouble swallowing, you may open the capsules and sprinkle the beads onto a small amount of soft food (e.g., applesauce) and swallow immediately without chewing. · Do not consume alcohol or any products containing alcohol while taking AVINZA, as it can lead to a dangerous increase in morphine levels. · This medication has a high risk of addiction, abuse, and misuse; store it safely and dispose of unused tablets properly. · Common side effects include constipation, nausea, drowsiness, and dizziness; report severe or persistent symptoms to your doctor. · Do not stop suddenly; withdrawal symptoms may occur; your doctor will guide you on tapering the dose. · Avoid driving or operating heavy machinery until you know how this medication affects you. |
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