PROTRIPTYLINE HYDROCHLORIDE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PROTRIPTYLINE HYDROCHLORIDE (PROTRIPTYLINE HYDROCHLORIDE).
Tricyclic antidepressant; inhibits reuptake of norepinephrine and serotonin at presynaptic neuronal membrane, increasing their concentrations in the synaptic cleft. May also downregulate beta-adrenergic and serotonin receptors.
| Metabolism | Hepatic; primarily via CYP2D6, with minor contributions from CYP1A2, CYP2C19, and CYP3A4. Metabolites: naphthalene ring hydroxylation, glucuronidation. |
| Excretion | Primarily renal (50-70% as metabolites, <5% unchanged); biliary/fecal elimination accounts for ~10-20%. |
| Half-life | Terminal elimination half-life: 54-92 hours (mean ~74 hours); due to long half-life, steady-state is reached in 11-18 days. |
| Protein binding | 92% bound primarily to alpha1-acid glycoprotein and albumin. |
| Volume of Distribution | Vd: 15-20 L/kg; indicates extensive tissue distribution (e.g., brain, lungs, liver). |
| Bioavailability | Oral: ~75% due to first-pass metabolism. |
| Onset of Action | Oral: anticholinergic effects within 1-2 hours; antidepressant effect begins after 1-2 weeks. |
| Duration of Action | Oral: single dose effects may persist 24-48 hours; antidepressant effects require continued dosing for weeks. |
| Molecular Weight | 263.38 |
15 mg orally 3 to 4 times daily, not to exceed 60 mg per day.
| Dosage form | TABLET |
| Renal impairment | GFR 30-89 mL/min: no adjustment required. GFR <30 mL/min: use with caution, reduce dose by 50%. Hemodialysis: supplemental dose not required. Peritoneal dialysis: insufficient data. |
| Liver impairment | Child-Pugh A: no adjustment. Child-Pugh B: reduce dose by 50%. Child-Pugh C: contraindicated. |
| Pediatric use | Adolescents (12-18 years): 5 mg orally 3 times daily; maximum 20 mg per day. Children <12 years: not recommended (safety and efficacy not established). |
| Geriatric use | Initiate at 5 mg orally 3 times daily; increase slowly. Maximum 20 mg per day. Monitor for orthostatic hypotension, cardiac arrhythmias, and anticholinergic effects. |
| 1st trimester | Limited human data; risk cannot be excluded. Animal studies have shown adverse effects. Use only if potential benefit justifies risk. |
| 2nd trimester | Limited human data; risk cannot be excluded. Consider risk-benefit. |
| 3rd trimester | Use in third trimester may cause adverse effects in neonate (e.g., irritability, respiratory depression). Avoid or use with caution. |
Clinical note
Comprehensive clinical and safety monograph for PROTRIPTYLINE HYDROCHLORIDE (PROTRIPTYLINE HYDROCHLORIDE).
| Placental transfer | Protriptyline crosses the placenta; degree not well quantified but expected to be significant based on lipophilicity and molecular weight. |
| Breastfeeding | Protriptyline is excreted into breast milk in small amounts. Monitor infant for drowsiness, irritability, and poor feeding. Consider risk-benefit; avoid if possible, especially in premature infants or those with impaired metabolism. |
■ FDA Black Box Warning
Increased risk of suicidal thinking and behavior in children, adolescents, and young adults with major depressive disorder and other psychiatric disorders. Not approved for use in pediatric patients.
| Serious Effects |
Hypersensitivity to protriptylineConcomitant use with MAOIs (risk of serotonin syndrome)Recent myocardial infarctionCoadministration with cisapride (risk of QT prolongation)
| Precautions | Activation of mania/hypomania, exacerbation of schizophrenia, cardiovascular toxicity (arrhythmias, QT prolongation, orthostatic hypotension), anticholinergic effects (urinary retention, constipation, blurred vision), seizures, serotonin syndrome, hypoglycemia, antagonism of guanethidine and clonidine. |
| Food/Dietary | Avoid high-tyramine foods (aged cheese, cured meats, pickled foods, broad beans) if taking MAOIs concurrently; however, protriptyline alone does not typically require tyramine restriction. Grapefruit juice may increase protriptyline levels; limit or avoid. Alcohol may potentiate CNS depression. |
Loading safety data…
| Lactation Rating | L3 (Moderately Safe) |
| Teratogenic Risk | First trimester: Limited data; animal studies show developmental toxicity at high doses; clinical data insufficient to rule out risk. Second and third trimesters: Risk of neonatal withdrawal (irritability, respiratory distress) if used near term; no structural abnormalities clearly associated. |
| Fetal Monitoring | Monitor maternal blood pressure, heart rate, mental status; fetal ultrasound for growth; neonatal assessment for withdrawal symptoms, respiratory depression, and anticholinergic effects (e.g., feeding difficulty, constipation). |
| Fertility Effects | In animal studies, protriptyline did not alter fertility significantly; human data are limited. May cause menstrual irregularities and sexual dysfunction, potentially affecting fertility. |
| Clinical Pearls | Protriptyline is a secondary amine tricyclic antidepressant (TCA) with greater CNS stimulation than sedation. It is unique among TCAs for its activating effects, making it useful in withdrawn or anergic patients. Monitor for orthostatic hypotension and anticholinergic effects (constipation, urinary retention, blurred vision). Due to its long half-life (54-92 hours), dose adjustments should be made cautiously. Avoid use in patients with glaucoma, prostatic hypertrophy, or recent myocardial infarction. |
| Patient Advice | Take exactly as prescribed; do not stop abruptly to avoid withdrawal symptoms. · May cause drowsiness or dizziness; avoid driving until you know how it affects you. · Report any urinary retention, severe constipation, or eye pain immediately. · Avoid alcohol and other CNS depressants. · Full therapeutic effect may take 2-4 weeks; do not stop if you don't feel better right away. · Use caution when rising from sitting or lying position to prevent falls. |