Dosing and uses of Mellaril (thioridazine)
Adult dosage forms and strengths
tablet
- 10mg
- 25mg
- 50mg
- 100mg
Schizophrenia
Initial 50-100 mg PO q8hr, THEn
200-800 mg/day PO divided q6-12hr
Depressive Disorders
25 mg PO q8hr; may titrate to effect (20-200 mg/day)
Renal Impairment
Dose adjustment not necessary in dialysis
Hepatic Disease
Initiate treatment at lower dose and titrate to effect (monitor)
Other Indications & Uses
Psychotic disorders, geriatric psychoneurotic manifestations, pediatric behavioral disorders
Pediatric dosage forms and strengths
tablet
- 10mg
- 25mg
- 50mg
- 100mg
Schizophrenia
<2 years: Safety and efficacy not established
2-12 years: 0.5-3 mg/kg/day divided q8hr PO, no more than 3 mg/kg/day
>12 years: Initial 50-100 mg PO q8hr; titrate to 200-800 mg/day PO divided q6-12hr
Potential toxic dose <6 years old: 3 mg/kg
Geriatric dosage forms and strengths
Initiate treatment at lower dose and titrate to effect (monitor)
Schizophrenia
Initial 50-100 mg PO q8hr, THEn
200-800 mg/day PO divided q6-12hr
Debilitated patients: Initiate treatment at lower dose
Depressive disorders
25 mg PO q8hr; may titrate to effect (20-200 mg/day)
Mellaril (thioridazine) adverse (side) effects
Frequency not defined
EPS (muscle stiffness, dystonia, parkinsonism, tardive dyskinesia, akathisia) (60%)
NMS (infrequent but serious)
Sedation
Anticholinergic effects
Weight gain
Oligomenorrhea/amenorrhea
Erectile dysfunction
Insomnia
Restlessness
Anxiety
Euphoria
Agitation
Depression
Weakness
Headache
Cerebral edema
Poikilothermia
Orthostatic hypotension
Tachycardia
Dizziness
Lens opacities (prolonged use)
Anorexia
Dyspepsia
Constipation
Ileus
Blood dyscrasia
ECG changes
Photosensitivity
Pruritis
Diarrhea
Galactorrhea
Ejaculatory disorder
Seizure (rare)
Priapism (rare)
Cholestatic jaundice (rare)
Warnings
Black box warnings
Patients with dementia-related psychosis who are treated with antipsychotic drugs are at an increased risk of death as shown in short-term controlled trials. The deaths appeared to be either cardiovascular (eg, heart failure, sudden death) or infectious (eg, pneumonia) in nature
This drug is not approved for the treatment of patients with dementia-related psychosis
Contraindications
Documented hypersensitivity to phenothiazines
Coma, severe hypotension, severe CNS depression, concurrency with large amounts of CNS depressants, poorly controlled seizure disorder, myelosuppression, subcortical brain damage
Any drugs or conditions that prolong QTc intervaL
Lactation
Cautions
Avoid using in children with suspected Reye's syndrome
Glaucoma, prostatic hypertrophy, stenosing PUD, tardive dyskinesia, history of NMS, Parkinson's disease, hypocalcemia, renal/hepatic impairment, patients who have exhibited a severe reaction to insulin or ECT, history of seizures, asthma, respiratory tract infections, cardiovascular disease
Risk of EPS, NMS, hypotension
Hypotension may be particularly severe in patients with pheochromocytoma or mitral insufficiency
Depresses hypothalamic thermoregulatory mechanism; exposure to extreme temperatures may cause hypo- or hyperthermia
In case of severe hypotension, use norepinephrine or phenylepinephrine, do NOT use epinephrine or dopamine
May need anticholinergic antiparkinsonian agent to counter EPs
Sales being discontinued in Canada
FDA Warning regarding off-label use for dementia in elderly
Pregnancy and lactation
Pregnancy category: C
Lactation: unknown
Pregnancy categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA: Information not available.
Pharmacology of Mellaril (thioridazine)
Mechanism of action
Piperazine phenothiazine agent; antagonist for the postsynaptic mesolimbic dopaminergic D2 receptors in the brain; decreases the release of hypothalamic and hypophyseal hormones
Pharmacokinetics
Half-Life elimination: 24 hr
Metabolism: Hepatic P450 enzyme CYP2D6
Enzymes inhibited: CYP2D6
Protein bound: 95%
Duration: 4-5 days
