TENATHAN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for TENATHAN (TENATHAN).
TENATHAN is a selective serotonin reuptake inhibitor (SSRI) that potentiates serotonergic activity in the central nervous system by inhibiting the reuptake of serotonin at the presynaptic neuronal membrane, leading to increased serotonin levels in the synaptic cleft.
| Metabolism | TENATHAN is extensively metabolized in the liver, primarily via cytochrome P450 enzymes CYP2D6 and CYP3A4. The major metabolite is N-desmethyltenathan, which has minimal pharmacological activity. Renal excretion of metabolites and unchanged drug accounts for elimination. |
| Excretion | Primarily renal excretion as unchanged drug (60-70%) and metabolites (20-30%); biliary/fecal elimination accounts for <10%. |
| Half-life | Terminal elimination half-life is 4-6 hours; in severe renal impairment (CrCl <30 mL/min) may extend to 8-12 hours, requiring dose adjustment. |
| Protein binding | 90-95% bound primarily to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Vd 1.5-2.0 L/kg, indicating extensive tissue distribution. Higher in obesity (up to 2.5 L/kg) due to lipophilicity. |
| Bioavailability | Oral: 40-60% (first-pass effect); Intramuscular: 75-85%; Intravenous: 100%. |
| Onset of Action | Oral: 30-45 minutes; Intravenous: 2-5 minutes; Intramuscular: 10-20 minutes. |
| Duration of Action | Oral: 4-6 hours; Intravenous: 2-4 hours; duration prolonged in hepatic impairment. Not recommended for long-term use due to tolerance development. |
| Molecular Weight | 353.4 |
1 tablet (40 mg) orally once daily, increased to 80 mg once daily if needed after 4 weeks.
| Dosage form | TABLET |
| Renal impairment | GFR ≥30 mL/min: no adjustment; GFR <30 mL/min: contraindicated. |
| Liver impairment | Child-Pugh A: no adjustment; Child-Pugh B: reduce dose to 20 mg once daily; Child-Pugh C: contraindicated. |
| Pediatric use | Not approved in pediatric patients; no established dosing. |
| Geriatric use | Initiate at 20 mg once daily due to increased sensitivity; titrate cautiously. |
| 1st trimester | TENATHAN is contraindicated in the first trimester due to documented teratogenicity in animal studies and potential for fetal harm. Use only if no alternative therapy exists and benefit justifies risk. |
| 2nd trimester | Use only if clearly needed; may cause fetal nephrotoxicity and oligohydramnios. Monitor amniotic fluid index if prolonged use. |
| 3rd trimester | Avoid in third trimester; may cause premature closure of ductus arteriosus and neonatal pulmonary hypertension. Use only if benefit outweighs risk. |
Clinical note
Comprehensive clinical and safety monograph for TENATHAN (TENATHAN).
| Placental transfer | TENATHAN crosses the placenta readily; cord blood concentrations approximate maternal levels. Animal studies show rapid transfer with accumulation in fetal tissues. |
| Breastfeeding | TENATHAN is excreted into breast milk in low concentrations. Due to potential for serious adverse reactions in nursing infants, decide whether to discontinue nursing or discontinue drug, taking into account importance of drug to mother. |
■ FDA Black Box Warning
WARNING: SUICIDAL THOUGHTS AND BEHAVIORS. Antidepressants increased the risk of suicidal thoughts and behaviors in pediatric and young adult patients in short-term studies. Closely monitor for clinical worsening, suicidality, or unusual changes in behavior. Advise families and caregivers about the need for close observation and communication with the prescriber.
| Serious Effects |
Hypersensitivity to TENATHAN or any componentThird trimester of pregnancyActive peptic ulcer diseaseCoagulation disorders including hemophilia or thrombocytopeniaSevere hepatic impairment (Child-Pugh class C)
| Precautions | 1. Serotonin syndrome: potentially life-threatening condition with co-administration of other serotonergic agents. 2. Discontinuation syndrome: gradual dose reduction recommended. 3. QT prolongation: caution in patients with risk factors for QT prolongation. 4. Hyponatremia: monitor in elderly and volume-depleted patients. 5. Bone fracture risk: increased risk in older adults. 6. Seizures: use with caution in patients with seizure disorders. |
| Food/Dietary |
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| Lactation Rating | L4 (Possibly Hazardous) |
| Teratogenic Risk | There is no data on TENATHAN in pregnancy. Animal studies have not been conducted. The fetal risk is unknown; therefore, use during pregnancy only if the potential benefit justifies the potential risk. |
| Fetal Monitoring | Monitor pregnancy status prior to initiation and throughout treatment. If pregnancy occurs during therapy, immediate discontinuation and fetal assessment should be considered. |
| Fertility Effects | In animal studies, TENATHAN demonstrated no adverse effects on fertility. Human data are lacking. |
| Avoid alcohol as it may enhance CNS depression and increase risk of liver toxicity. Grapefruit may increase drug levels; avoid excessive intake. No specific dietary restrictions, but a low-fat meal may reduce absorption delay. |
| Clinical Pearls | TENATHAN is a selective norepinephrine reuptake inhibitor (SNRI) used for neuropathic pain and fibromyalgia. Monitor for hypertension due to noradrenergic effects; baseline and periodic BP checks recommended. Avoid abrupt discontinuation to prevent withdrawal symptoms (dizziness, nausea, headache). Dose adjustment needed in renal impairment (CrCl <30 mL/min). |
| Patient Advice | Take TENATHAN exactly as prescribed, usually once daily with or without food. · Do not stop abruptly; taper under doctor's guidance to avoid side effects. · Report any signs of hypertensive crisis: severe headache, blurred vision, chest pain. · Avoid driving or operating machinery until you know how TENATHAN affects you. · If you miss a dose, take it as soon as you remember unless it's close to next dose; do not double up. |