>>213892575
If we focus on fastest-acting drugs when injected intravenously, the main factor is how quickly they reach the brain and produce their effects. Here’s a ranked breakdown:
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Fastest-Acting IV Drugs
1. Ultra-Short Barbiturates
Examples: Thiopental, methohexital, pentobarbital
Onset: 10-15 seconds
Effect: Loss of consciousness, anesthesia
Notes: Extremely dangerous in uncontrolled doses respiratory arrest, death
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2. Propofol
Onset: 15–30 seconds
Effect: Rapid sedation, full unconsciousness
Notes: Only used in hospitals; overdose causes immediate respiratory and cardiac arrest
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3. Opioids (potent IV forms)
Examples: Fentanyl, remifentanil
Onset: 1–3 minutes
Effect: Euphoria, analgesia, sedation; high doses respiratory depression
Notes: Fentanyl is extremely potent; micrograms can be fatal
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4. Cocaine (IV)
Onset: <1 minute
Effect: Intense euphoria, increased heart rate and blood pressure
Notes: High cardiovascular risk heart attack, stroke
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5. Other IV Benzodiazepines
Examples: Midazolam, lorazepam
Onset: 1–5 minutes
Effect: Sedation, anxiolysis, amnesia
Notes: Safer than barbiturates; deadly when combined with alcohol or opioids
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6. Potassium Chloride (Cardiotoxic)
Onset: Seconds to minutes
Effect: Stops the heart
Notes: Extremely lethal; used in lethal injection or extreme medical scenarios
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Takeaway:
Thiopental, propofol, and IV fentanyl are among the fastest-acting depressants/sedatives.
Potassium chloride acts almost immediately but is not a recreational drug—it’s purely toxic.
Speed of action is why IV use is extremely dangerous; effects are rapid and often irreversible without medical support.
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