Paroxetine

ADMINISTRATION ROUTES:

PO, NG

ALTERNATIVE NAMES:

Aropax, Loxamine

ICU INDICATIONS:

1. Antidepressant

Note: it is uncommon for antidepressants to be commenced in patients in the ICU. Many ICU patients have situational or reactive depressio and the risks of medication may outweigh the benefits (see WARNINGS).

PRESENTATION AND ADMINISTRATION:

PO:

Tablets:

Aropax 20 mg tablets (white), Loxamine 20 mg tablets (white)

NG:

Tablets can be crushed for administration via NG tube

DOSAGE:*

PO:

20 - 60 mg OD

DOSAGE IN RENAL FAILURE AND RENAL REPLACEMENT THERAPY:

Dose in renal impairment

Dose in renal replacement therapy

DOSAGE IN PAEDIATRICS:

0.4 mg/kg OD

Increase to max 1 mg/kg OD

CLINICAL PHARMACOLOGY:

Paroxetine is a potent & selective serotonin-reuptake inhibitor (SSRI) antidepressant. It blocks serotonin reabsorption leading to changes in brain receptor regulation. It is well absorbed from the gastrointestinal tract and undergoes first-pass metabolism. Steady state levels are reached 7 - 14 days after starting treatment. It is extensively distributed into tissues with only around 1% remaining in the plasma, of which 95% is protein bound once therapeutic concentrations have been reached.

CONTRAINDICATIONS:

1. Hypersensitivity to paroxetine or other SSRIs

WARNINGS:

Use in Patients With Concomitant Illness

Clinical experience with SSRIs in patients with concomitant systemic illness is limited. Caution is advised in using SSRIs in patients with diseases or conditions that could affect metabolism or haemodynamic responses.

Suicidality

Patients with major depressive disorder (MDD), both adult and paediatric, may experience worsening of their depression and/or the emergence of suicidal ideation and behaviour (suicidality) or unusual changes in behaviour, whether or not they are taking antidepressant medications, and this risk may persist until significant remission occurs.

Hyponatraemia

Cases of hyponatraemia (some with serum sodium < 110 mmol/L) have been reported. The hyponatraemia appeared to be reversible when the SSRI was discontinued.

PRECAUTIONS:

General:

Anaphylactoid events, including bronchospasm, angioedema, laryngospasm, and urticaria alone and in combination, have been reported.

Pulmonary events, including inflammatory processes of varying histopathology and/or fibrosis, have been reported rarely. These events have occurred with dyspnoea as the only preceding symptom.

Published case reports have documented the occurrence of bleeding episodes in patients treated with psychotropic drugs that interfere with serotonin reuptake. Subsequent epidemiological studies, both of the case-control and cohort design, have demonstrated an association between use of psychotropic drugs that interfere with serotonin reuptake and the occurrence of upper gastrointestinal bleeding.

Laboratory Tests:

No tests in addition to routine ICU tests are required.

Drug/Laboratory Test Interactions:

None noted.

IMPORTANT DRUG INTERACTIONS IN ICU:

The combination of tramadol and SSRIs should be used with caution due to the increased risk of serotonin syndrome with concomitant use.

Patients on stable doses of phenytoin and carbamazepine have developed elevated plasma anticonvulsant concentrations and clinical anticonvulsant toxicity following initiation of concomitant paroxetine treatment.

Serotonin release by platelets plays an important role in haemostasis. Epidemiological studies of the case-control and cohort design that have demonstrated an association between use of drugs that interfere with serotonin reuptake and the occurrence of upper gastrointestinal bleeding have also shown that concurrent use of an NSAID or aspirin potentiated the risk of bleeding.

ADVERSE REACTIONS:

Body as a Whole

Flu syndrome

Cardiovascular System

Vasodilatation

Digestive System

Nausea, diarrhoea, anorexia, dry mouth, dyspepsia

Nervous System

Insomnia, anxiety, nervousness, somnolence, tremor

Respiratory System

Pharyngitis, sinusitis

Skin and Appendages

Sweating, rash