Perigen5 mg/ml

Perigen is a first-generation (typical) antipsychotic of the butyrophenone class. Its evidence-based indications are classified below by strength of evidence.

Established / FDA-approved uses

• Schizophrenia: management of manifestations of acute and chronic psychotic disorders, including schizophrenia.
• Tourette's disorder: control of tics and vocal utterances in moderate-to-severe cases that fail to respond to standard treatment.
• Severe behavioural problems in children (short-term): combative, explosive hyperexcitability that cannot be accounted for by immediate provocation.
• Hyperactive children with severe conduct disorders: short-term adjunctive treatment when other measures have failed, in children who show excessive motor activity with accompanying conduct disorders.

Guideline-supported / commonly used off-label

• Acute agitation and acute psychotic episodes (including in emergency and psychiatric-inpatient settings), often via the injectable formulation, based on long-standing clinical practice and guideline support rather than a specific labelled indication for this exact use.
• Persistent hiccups unresponsive to other measures - a long-standing off-label use.
• Delirium-related agitation in hospitalised patients (off-label; evidence is mixed and use should be short-term with careful monitoring).

Perigen is not FDA-approved for treatment of dementia-related psychosis or behavioural disturbances in elderly patients with dementia (see Precautions and Warnings).

Each formulation of Haloperidol contains haloperidol as the active pharmaceutical ingredient. Available forms typically include:

• Tablets: Haloperidol 0.5 mg, 1.5 mg, 2 mg, 5 mg, and 10 mg
• Oral solution/drops: Haloperidol 2 mg/mL
• Injection (immediate-release, lactate salt): Haloperidol 5 mg/mL for IM use
• Injection (long-acting decanoate salt): Haloperidol decanoate 50 mg/mL or 100 mg/mL for deep IM use

Excipients vary by manufacturer and formulation.

Perigen is a butyrophenone-derivative, first-generation ('typical') antipsychotic that has been used in psychiatric practice for decades. It works primarily by blocking post-synaptic dopamine D2 receptors in the brain, which reduces the positive symptoms of psychosis (hallucinations, delusions, disordered thinking). It is available as oral tablets, an oral solution, an immediate-release injection for acute agitation, and a long-acting depot injection for maintenance therapy.

Perigen is a high-potency typical antipsychotic, meaning it is associated with a comparatively higher risk of extrapyramidal symptoms and a lower risk of sedation and anticholinergic effects relative to some low-potency agents.

Perigen belongs to the butyrophenone class of first-generation (typical/conventional) antipsychotics, also referred to as neuroleptics.

Mechanism of Action

Haloperidol exerts its antipsychotic effect mainly through potent, non-selective antagonism of post-synaptic dopamine D2 receptors, particularly in the mesolimbic and mesocortical pathways, which is thought to underlie its efficacy against positive psychotic symptoms. Blockade of D2 receptors in the nigrostriatal pathway accounts for its prominent extrapyramidal side effects, while blockade in the tuberoinfundibular pathway raises prolactin levels. Haloperidol also has weaker antagonist activity at alpha-1 adrenergic receptors, contributing to orthostatic hypotension, and minimal anticholinergic or antihistaminic activity compared with low-potency typical antipsychotics.

Pharmacokinetics

• Absorption: Oral bioavailability approximately 60-70%; peak plasma concentration in 2-6 hours after oral dosing.
• Distribution: Highly lipophilic, crosses the blood-brain barrier and placenta, and is distributed into breast milk; plasma protein binding is approximately 90%.
• Metabolism: Extensively hepatic, mainly via CYP3A4 and CYP2D6 and via glucuronidation; forms an active reduced metabolite.
• Elimination half-life: Approximately 14-26 hours (oral); longer for the decanoate depot formulation (weeks).
• Excretion: Primarily via bile/faeces and urine as metabolites.

Perigen tablets and oral solution may be taken with or without food; taking with food or milk may reduce stomach upset. The oral solution should be measured with the calibrated dropper/dispenser provided. The immediate-release injection is given by deep intramuscular injection only (not intended for intravenous use - see Precautions and Warnings regarding QT prolongation risk with unapproved IV administration). The decanoate depot injection is given by deep intramuscular injection only and must never be given intravenously. Do not stop or change the dose of Perigen without consulting your physician.

Perigen has several clinically significant drug interactions:

• Other QT-prolonging drugs (e.g. certain antiarrhythmics, some antibiotics such as macrolides and fluoroquinolones, some antidepressants): additive risk of QT prolongation and torsades de pointes; combination should generally be avoided (see Precautions and Warnings).
• CNS depressants and alcohol (opioids, benzodiazepines, sedative-hypnotics): additive sedation and risk of respiratory depression.
• CYP2D6 and CYP3A4 inhibitors (e.g. fluoxetine, paroxetine, ketoconazole, ritonavir): can increase plasma levels of Perigen, increasing risk of side effects including QT prolongation; dose adjustment may be needed.
• CYP3A4/2D6 inducers (e.g. carbamazepine, rifampin, phenobarbital): may reduce plasma levels of Perigen, reducing efficacy.
• Levodopa and other dopamine agonists: Perigen antagonises their therapeutic effect due to opposing dopaminergic actions.
• Lithium: rare reports of an encephalopathic syndrome (confusion, extrapyramidal symptoms, high fever) with concurrent high-dose use; monitor closely if combined.
• Anticholinergic drugs: additive anticholinergic effects; may also increase risk of tardive dyskinesia with prolonged combined use.

Common

• Extrapyramidal symptoms - dystonia, akathisia (restlessness), drug-induced parkinsonism (tremor, rigidity, bradykinesia); notably more frequent with Perigen than with many other antipsychotics due to its high D2-receptor potency
• Sedation/drowsiness
• Dry mouth, constipation, blurred vision
• Insomnia, headache, anxiety, agitation
• Orthostatic hypotension
• Hyperprolactinemia - galactorrhea, gynecomastia, menstrual irregularities, sexual dysfunction
• Weight change

Serious (less common but important)

• Tardive dyskinesia - potentially irreversible involuntary movements, risk increases with dose and duration of treatment (see Precautions and Warnings).
• Neuroleptic malignant syndrome (NMS) - rare, potentially fatal (see Precautions and Warnings).
• QT prolongation and torsades de pointes, which can be fatal (see Precautions and Warnings).
• Seizures (lowered seizure threshold).
• Leukopenia, neutropenia, and rarely agranulocytosis.
• Severe hypersensitivity reactions, laryngospasm, or bronchospasm (rare).

Pregnancy: Perigen should be used during pregnancy only if clearly needed and if the potential benefit justifies the potential risk to the fetus; please consult a physician. Neonates exposed to antipsychotic drugs, including Perigen, during the third trimester are at risk of extrapyramidal and/or withdrawal symptoms after delivery (agitation, abnormal muscle tone, tremor, feeding difficulty, respiratory distress), which may vary in severity and may require extended hospital monitoring.

Lactation: Perigen is excreted into breast milk and has been associated with adverse effects (drowsiness, extrapyramidal symptoms) in some breastfed infants. It should be used during breastfeeding only if the potential benefit outweighs the potential risk, and only under medical advice, with the infant monitored for sedation and abnormal movements.

Boxed warning-level risks

• Increased mortality in elderly patients with dementia-related psychosis: Elderly patients with dementia-related psychosis treated with antipsychotic drugs, including Perigen, are at increased risk of death compared with placebo, most commonly from cardiovascular causes (e.g. heart failure, sudden death) or infection (e.g. pneumonia). Perigen is not approved for the treatment of dementia-related psychosis.
• QT prolongation and torsades de pointes: Perigen can prolong the QT interval, and cases of torsades de pointes and sudden death have been reported, particularly with intravenous administration (a route not FDA-approved for this drug) and at doses higher than recommended. ECG monitoring is advised in patients with risk factors for QT prolongation, and concurrent use with other QT-prolonging drugs should generally be avoided.

Other important warnings

• Neuroleptic malignant syndrome (NMS): a rare but potentially fatal reaction presenting with hyperthermia, muscle rigidity, altered mental status, and autonomic instability; requires immediate discontinuation and supportive treatment.
• Tardive dyskinesia: may develop with prolonged treatment and may be irreversible; risk increases with cumulative dose and duration; use the lowest effective dose for the shortest necessary duration.
• Extrapyramidal symptoms requiring dose adjustment or additional treatment (e.g. anticholinergic agents) in some patients.
• Use with caution in patients with cardiovascular disease, electrolyte disturbances (hypokalemia, hypomagnesemia), history of seizures, severe hepatic impairment, or in those at risk of aspiration pneumonia.
• May impair mental/physical abilities; caution advised with driving or operating machinery until effects are known.

Overdose of Perigen may present with exaggerated pharmacological effects, including severe extrapyramidal symptoms, sedation, coma, hypotension, respiratory depression, and QT prolongation with risk of serious ventricular arrhythmia. There is no specific antidote. In case of suspected overdose, seek immediate medical attention or contact a poison control center/emergency services right away; treatment is supportive, with cardiac (ECG) monitoring and airway/circulatory support as needed in a hospital setting.

Store Perigen at room temperature (below 30°C), protected from light and moisture. Keep out of reach of children. Do not freeze the injectable formulations.

Elderly

Perigen should be used with caution in elderly patients, starting with lower doses, due to increased sensitivity to sedation, orthostatic hypotension, and extrapyramidal effects. Elderly patients with dementia-related psychosis have an increased risk of death with antipsychotic use (see Precautions and Warnings) - Perigen is not approved for this use.

Pediatric

Perigen is approved for use in children 3 years of age and older for specific indications (psychotic disorders, Tourette's disorder, severe behavioural problems), using weight-based dosing with careful titration. Safety and efficacy in children under 3 years of age have not been established.

Hepatic impairment

Use with caution and lower starting doses; Perigen is extensively metabolised by the liver.

Renal impairment

No formal dose-adjustment schedule is established; use with caution and monitor closely.

Duration of treatment with Perigen depends on the indication: acute agitation/psychosis may require only short-term use (days), while schizophrenia and Tourette's disorder often require longer-term maintenance therapy under ongoing psychiatric supervision, using the lowest effective dose for the shortest duration necessary to minimize risks such as tardive dyskinesia. Any decision to continue, adjust, or stop Perigen should be made by the treating physician.

Haloperidol is classified as a first-generation (typical) antipsychotic, butyrophenone derivative.

Haloperidol acts primarily as a potent antagonist at post-synaptic dopamine D2 receptors in the central nervous system, reducing dopaminergic neurotransmission in the mesolimbic pathway to relieve positive psychotic symptoms. It has weaker antagonist effects at alpha-1 adrenergic receptors and minimal anticholinergic/antihistaminic activity relative to low-potency typical antipsychotics.

C

Perigen is approved for children 3 years of age and older for the management of psychotic disorders, Tourette's disorder (moderate-to-severe, refractory tics), and severe behavioural problems (combative, explosive hyperexcitability) or hyperactivity with conduct disorders, using cautious weight-based dosing (approximately 0.05-0.075 mg/kg/day, divided). Children should be started on the lowest possible dose, with gradual titration and close monitoring for extrapyramidal symptoms and sedation. Safety and efficacy of Perigen in children below 3 years of age have not been established, and it should not be used in this age group.