From the Guidelines
Intravenous (IV) ketamine has a rapid onset of action, typically beginning within 1 minute after administration. The onset of action for IV ketamine can range from 30 seconds to 1 minute, with peak effects usually reached within 5-10 minutes 1. This rapid onset is due to ketamine's high lipid solubility, allowing it to quickly cross the blood-brain barrier and reach its site of action.
Key Points
- The standard IV dose for procedural sedation or anesthesia ranges from 1-2 mg/kg, while subanesthetic doses for pain or depression (0.1-0.5 mg/kg) have a similar rapid onset but less intense effects 1.
- The quick onset makes IV ketamine valuable for emergency situations requiring rapid sedation or analgesia.
- Monitoring equipment and personnel should be immediately available when administering IV ketamine, as cardiovascular effects (typically increased heart rate and blood pressure) and dissociative effects can develop quickly 1.
- The duration of action after a single IV dose is relatively short, typically 10-15 minutes for significant anesthetic effects, though some effects may persist for 1-2 hours 1.
Considerations
- Ketamine produces a dose-dependent increase in heart rate, blood pressure, and cardiac output, mediated through stimulation of the sympathetic nervous system, and its use potentially is dangerous and should be avoided in patients with ischemic heart disease, cerebrovascular disease, or hypertension 1.
- Emergence reaction, manifested by floating sensations, vivid dreams, hallucinations, and delirium, has been reported in 10%–30% of adults, and the use of midazolam in combination with ketamine is reported to minimize this reaction 1.
From the FDA Drug Label
The average amount required to produce 5 to 10 minutes of surgical anesthesia within 30 seconds following injection is 2 mg/kg. Administer ketamine hydrochloride injection slowly (i.e., over a period of 60 seconds).
The onset of action for IV ketamine is approximately 30 seconds to produce 5 to 10 minutes of surgical anesthesia, with the average dose being 2 mg/kg 2.
- The administration rate should be slow, over a period of 60 seconds, to avoid respiratory depression and enhanced vasopressor response.
- Key points to consider when administering IV ketamine include:
- Individualized dosing and titration to the desired clinical effect
- Monitoring of vital signs and availability of emergency airway equipment
- Potential for salivation, vomiting, and aspiration during administration.
From the Research
IV Ketamine Onset
- The onset of IV ketamine is not explicitly stated in the provided studies, but its pharmacokinetics can be inferred from the available data 3.
- Ketamine undergoes extensive first-pass metabolism, which affects its oral bioavailability, but IV administration allows for rapid maximum plasma concentrations 3.
- The effects of ketamine can be seen quickly after administration, with studies showing rapid-acting antidepressant effects and analgesic properties 3, 4.
- The exact onset time of IV ketamine is not specified in the provided studies, but its rapid action suggests a quick onset of effects.
Related Studies
- A study on nebulized ketamine for acute pain management found that it had equivalent efficacy to active controls, but did not provide information on the onset of IV ketamine 5.
- Consensus guidelines on the use of IV ketamine infusions for acute pain management discuss its effectiveness, but do not specify the onset time 4.
- Studies on the effects of ketamine on resting state connectivity and mood improvement in depression provide insight into its mechanisms of action, but do not address the onset of IV ketamine specifically 6, 7.
Pharmacokinetics and Pharmacodynamics
- Ketamine's pharmacokinetics and pharmacodynamics are complex, involving multiple pathways and receptors, which can affect its onset and duration of action 3.
- The use of S-ketamine, which is more potent than the R-enantiomer, may influence the onset and efficacy of IV ketamine, but this is not explicitly stated in the provided studies 3.