Depnox SR150 mg

Depnox SR is an atypical antidepressant approved for the following indications:

• Major depressive disorder (MDD) - an established, FDA-approved indication for the acute and maintenance treatment of depression in adults.
• Prevention of seasonal affective disorder (SAD) - the extended-release formulation is FDA-approved to prevent seasonal major depressive episodes in patients with a history of SAD, when started before the onset of symptoms in autumn/winter.
• Smoking cessation aid - a specific sustained-release formulation and dosing regimen of Depnox SR is FDA-approved as an aid to smoking cessation treatment, used together with counselling and behavioral support.

Off-label uses (based on clinical experience and limited evidence, not FDA-approved) include adjunctive treatment of antidepressant-associated sexual dysfunction and adjunctive use for weight management in select patients under specialist supervision. Off-label use should only be undertaken on a physician's advice.

Each tablet contains Bupropion Hydrochloride as the active pharmaceutical ingredient, available in immediate-release, sustained-release (SR), and extended-release (XL) formulations in various strengths (commonly 100 mg, 150 mg, and 300 mg), along with standard pharmaceutical excipients.

Depnox SR is a synthetic aminoketone antidepressant, chemically and pharmacologically distinct from tricyclic, tetracyclic, selective serotonin reuptake inhibitor (SSRI), and other commonly used antidepressant classes. It is classified as a norepinephrine-dopamine reuptake inhibitor (NDRI).

Depnox SR is used in the management of major depressive disorder, prevention of seasonal affective disorder, and as an aid to smoking cessation. It is notable among antidepressants for having a low incidence of sexual side effects and weight gain.

Depnox SR belongs to the class of atypical antidepressants, specifically a norepinephrine-dopamine reuptake inhibitor (NDRI), also used as a smoking cessation aid.

Mechanism of Action

The precise mechanism by which Bupropion Hydrochloride exerts its antidepressant and smoking-cessation effects is not fully known, but it is thought to be mediated through its inhibition of the neuronal reuptake of norepinephrine and dopamine, with minimal effect on serotonin reuptake. It does not inhibit monoamine oxidase.

Pharmacokinetics

Bupropion Hydrochloride is well absorbed orally and extensively metabolized in the liver, primarily via CYP2B6, to an active metabolite (hydroxybupropion) that contributes to its clinical effect. It is a notable inhibitor of the CYP2D6 enzyme. Elimination is mainly renal, as metabolites.

Tablets of Depnox SR should be swallowed whole with water and must not be crushed, split, or chewed, particularly the sustained-release and extended-release formulations, as this can increase the risk of seizures and side effects due to rapid drug release. May be taken with or without food. Doses should be evenly spaced as recommended for each formulation to minimize seizure risk.

Depnox SR has several well-established, clinically significant interactions:

• Monoamine oxidase inhibitors (MAOIs): Concurrent use or use within 14 days of stopping an MAOI is contraindicated due to risk of hypertensive reactions; allow at least 14 days between stopping an MAOI and starting Depnox SR.
• Drugs that lower seizure threshold (e.g. antipsychotics, other antidepressants, theophylline, systemic corticosteroids, tramadol): increased seizure risk when combined with Depnox SR.
• CYP2D6 substrates (e.g. certain tricyclic antidepressants, tamoxifen, beta-blockers, antiarrhythmics): Depnox SR is a potent CYP2D6 inhibitor and can raise plasma levels of these drugs, requiring dose adjustment.
• Drugs that induce or inhibit CYP2B6 (e.g. ritonavir, efavirenz, carbamazepine): may alter Depnox SR plasma concentrations.
• Alcohol: concurrent heavy alcohol use may increase the risk of seizures and neuropsychiatric adverse effects; abrupt discontinuation of alcohol while on Depnox SR is contraindicated (see Contraindications).
• Nicotine replacement therapy: combined use may increase blood pressure; monitoring is advised, particularly when Depnox SR is used for smoking cessation.

Common side effects of Depnox SR include:

• Dry mouth
• Insomnia and vivid dreams
• Headache
• Nausea and vomiting
• Constipation
• Tremor
• Dizziness
• Agitation, anxiety, or irritability
• Excessive sweating
• Weight loss (rather than the weight gain seen with some other antidepressants)

Less common but serious effects include dose-dependent seizures, increased blood pressure (sometimes marked, especially with concurrent nicotine replacement therapy), and activation of mania/hypomania in susceptible individuals. As with all antidepressants, worsening depression or emergence of suicidal thoughts can occur, particularly early in treatment (see Precautions and Warnings). Unlike many other antidepressants, Depnox SR has a comparatively low incidence of sexual dysfunction.

Pregnancy: Data on Depnox SR use in pregnancy are limited. Depnox SR should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus; use only if clearly needed and under a physician's guidance. Untreated depression itself carries risks, so the decision to continue or stop treatment during pregnancy should be individualized with a physician.

Lactation: Depnox SR and its metabolites are excreted into human breast milk. Because of the potential for serious adverse reactions in a nursing infant, a decision should be made whether to discontinue breastfeeding or discontinue Depnox SR, taking into account the importance of the drug to the mother; consult a physician before use while breastfeeding.

Boxed Warning: Suicidal Thoughts and Behaviors

Antidepressants, including Depnox SR, increase the risk of suicidal thinking and behavior in children, adolescents, and young adults (up to age 24) with major depressive disorder and other psychiatric disorders. Patients of all ages should be monitored closely for clinical worsening, and for emergence of suicidal thoughts and behaviors, especially during the first few months of therapy and following dose changes.

Seizure Risk

Depnox SR is associated with a dose-dependent risk of seizures, which is higher than with many other antidepressants. The risk increases with dose, so the maximum recommended dose should not be exceeded, and doses should be divided/spaced as directed for each formulation. Risk factors include predisposing conditions, high doses, and concomitant use of other drugs that lower seizure threshold.

Activation, Insomnia, and Agitation

Restlessness, agitation, anxiety, and insomnia are relatively common; taking the last daily dose earlier in the day can reduce sleep disturbance.

Hypertension

Depnox SR can cause or worsen high blood pressure, sometimes severely; this is particularly notable when combined with nicotine replacement therapy for smoking cessation. Blood pressure should be measured before starting treatment and monitored periodically thereafter.

Neuropsychiatric Symptoms

Monitor for worsening depression, mania/hypomania activation, or emergence of suicidal thoughts, especially early in treatment or after dose changes (see Boxed Warning).

Drug Interactions via CYP2D6

Depnox SR is a notable inhibitor of the CYP2D6 enzyme; other medicines metabolized by this pathway should be reviewed for dose adjustment (see Interactions).

Depnox SR is generally favored in patients where avoiding the sexual side effects or weight gain associated with some other antidepressant classes is a treatment priority.

Overdose with Depnox SR can cause seizures, hallucinations, loss of consciousness, tachycardia, and in severe cases cardiac arrhythmias or cardiac arrest. Overdose is a medical emergency. If overdose is suspected, seek immediate medical attention or contact emergency services/poison control right away. Treatment is supportive and should be provided in a hospital setting with cardiac monitoring; do not attempt specific home treatment.

Store at room temperature (below 30°C), away from light and moisture. Keep out of reach of children.

Pediatric Use

Safety and efficacy of Depnox SR for depression have not been established in patients under 18 years of age. It is not approved for use in children.

Geriatric Use

Elderly patients may be more sensitive to the central nervous system effects of Depnox SR; use the lowest effective dose and monitor closely, particularly in those with renal or hepatic impairment.

Renal Impairment

Use a reduced dose and/or frequency; see Dosage and Administration.

Hepatic Impairment

Use with caution and reduced dose, particularly in severe hepatic cirrhosis; see Dosage and Administration.

Duration of treatment with Depnox SR depends on the indication: depression treatment is typically continued for at least several months after response to reduce relapse risk, and long-term maintenance may be recommended by the treating physician; seasonal affective disorder prevention is used seasonally (autumn to early spring); smoking cessation treatment is typically given for 7-12 weeks. Do not stop treatment abruptly without medical advice, as gradual tapering may be recommended.

Bupropion Hydrochloride is classified as an atypical antidepressant / norepinephrine-dopamine reuptake inhibitor (NDRI), and is also used as a smoking cessation aid.

Bupropion Hydrochloride inhibits the neuronal reuptake of norepinephrine and dopamine, with minimal effect on serotonin reuptake, thereby increasing the availability of these neurotransmitters in the central nervous system. It does not inhibit monoamine oxidase.

Category C (legacy FDA classification)

Depnox SR is not approved for the treatment of depression in patients under 18 years of age; safety and efficacy have not been established in this population. Use in children and adolescents should only occur under close specialist supervision when considered clinically necessary.