She is complaining of vomiting and dizziness. On Exmination ;vitals signs HR 120 , BP 150/60, afebrile, RR 20,Spo2 100% in R.A
Blood sugars is 6 mmol/l . Systematic exam unremarkable apart from her being drowsy with GCS 14/15 and she is noted to have tremor.
Q1.What are the expected toxicity?
Q2.How will you manage this patient?
Depressed Lady Cont'
Thank you all for your excellent comments
•Venlafaxine are serotonin-norepinephrine reuptake inhibitors ( SNRI)
•Toxicity includes CNS: ataxia , sedation ,Tremor and seizure are common after SNRI
•CVS: effects are usually not life threatening and includes tachycardia , hypotension , SNRI can cause hypertension , severe venlafaxine overdose have been associated with QRS and QT prolongation and cardiac conduction defect
•Serotonin Syndrome is described with overdose of SNRI
Management:
•Laboratory investigation includes : electrolytes , glucose , ABG , ECG , and ruling out other co ingestion
•Usually supportive with CNS and cardiac monitoring
•Activated charcoal can be given if appropriate conditions and if no contraindication, this patient is already drowsy so not indicated
•For serotonin syndrome benzo can be used for tremor and agitation and seizure
•Severe serotonin syndrome with hyperthermia needs aggressive cooling and intubation with paralysis
•Cyproheptadine is also reported to be effective in severe serotonin syndrome
•Symptomatic patient need admission for observation
References:
•Olson’s Poisoning and Drug Overdose , 6th edition ,
• Venlafaxine is an antidepressant within the serotonin-norepinephrine reuptake inhibitor (SNRI) class of medications. It exerts its effects primarily by blocking the transporters involved in the reuptake of the neurotransmitters serotonin and norepinephrine, therefore leaving more active neurotransmitter in the synapse.
• All SNRIs cause sympathetic nervous system stimulation via inhibition of norepinephrine reuptake, which predisposes patients to tachycardia,
hypertension, diaphoresis, tremor, and mydriasis .
In overdose :
• CVS
- Large overdoses of venlafaxine can produce severe global impairment of left ventricular systolic contraction with a markedly
reduced ejection fracture .
-ECG abnormalities are common following intentional SNRI overdose . Sinus tachycardia is the most common ECG abnormality observed, but QRS widening and QT interval prolongation have also been reported.
• CNS
Generalized seizures t'end to occur early after ingestion and are more common after overdose with venlafaxine compared to SSRI exposures .
*Treatment
• Asymptotic:
-observed for 6 hours.
-Patients ingesting extended-release preparations require additional observation for at least
24 hours due to the possibility of delayed
• Symptomatic
-patients should be admitted to a monitored bed.
-IV access, cardiac rhythm monitor, and ECG
-Single-dose activated charcoal if ingestion within 1 h
-Consider whole-bowel irrigation with large (>4000 milligrams)
-Treat seizures with IV benzodiazepines
-Sodium bicarbonate for prolonged QRS complex
-Magnesium sulfate for QTc interval prolongation
-IV fluids and direct-acting vasopressors for hypotension
Gastric lavage and ipecac syrup are contraindicated due to the potential for seizures and aspiration
SNRI TOXICITY
MILD TO MODERATE
INCLUDE tachycardia, hypertension, diaphoresis, tremor, mydriasis, SEDATION,RHABDOMYOLYSIS,QRS widening, QT prolongation.
Management
admission+monitoring
Cardiac monitoring
A single dose of activated charcoal 50 g.