KETAMINE 50MG/ML INJECTION

Ketamine Hydrochloride 50 mg/mL is a rapid-acting parenteral anaesthetic that produces a distinctive dissociative anaesthetic state characterised by profound analgesia, sedation, amnesia, and catalepsy, while pharyngeal-laryngeal protective reflexes are maintained.

Ketamine Hydrochloride 50 mg/mL acts primarily as a non-competitive antagonist at N-methyl-D-aspartate (NMDA) receptors in the central nervous system, interrupting associative pathways in the brain before producing somesthetic sensory blockade, a state often described as "dissociative anaesthesia."

Ketamine is indicated for: induction and maintenance of general anaesthesia (IV or IM) for diagnostic and surgical procedures; induction prior to administration of other general anaesthetic agents; supplementation of low-potency anaesthetic agents; procedural sedation and analgesia (e.g., wound debridement, dressing changes, burn care, orthopaedic manipulations); and analgesia in sub-anaesthetic doses. Off-label applications include treatment-resistant depression and management of acute pain in emergency settings.

Ketamine 50 mg/mL is administered exclusively by healthcare professionals trained in anaesthesia and airway management. Resuscitation equipment, oxygen, and a specific reversal agent must be available at all times.

General Anaesthesia, Intravenous

•     Induction: 1–4.5 mg/kg IV administered slowly over 60 seconds. A dose of 2 mg/kg typically produces surgical anaesthesia within 30 seconds, lasting 5–10 minutes.

•     When used with adjuvant drugs (e.g., midazolam): 0.5–2 mg/kg IV.

•     Maintenance: supplemental doses of 50% of the induction dose as required, or 0.1–0.5 mg/kg/min IV continuous infusion.

General Anaesthesia, Intramuscular

•     Induction: 6.5–13 mg/kg IM. A dose of 10 mg/kg typically produces surgical anaesthesia within 3–4 minutes, lasting 12–25 minutes.

•     When adjuvant drugs are used: 4–10 mg/kg IM.

Sub-anaesthetic Analgesia (Off-label)

•     0.1–0.5 mg/kg IV (sub-anaesthetic doses for acute pain management in emergency and procedural settings).

•     Paediatric procedural sedation: 4–5 mg/kg IM (specialist guidance required).

Pre-medication

•     An anticholinergic agent (atropine, glycopyrrolate) should be administered before induction to reduce ketamine-induced hypersalivation.

•     A benzodiazepine (e.g., midazolam or diazepam) is commonly co-administered to reduce the incidence of emergence reactions.

Side effects vary in frequency and severity. Not every patient will experience all listed effects. Seek immediate medical attention for any serious or unexpected reactions.

•     Respiratory monitoring: Ketamine preserves airway reflexes but does not guarantee against aspiration. Opioids or benzodiazepines used concomitantly increase respiratory depression risk; monitoring with pulse oximetry is mandatory.

•     Cardiovascular stimulation: Blood pressure and heart rate increases can be pronounced; use with extreme caution in patients with established cardiovascular disease.

•     Emergence reactions: Occur in a significant proportion of patients, particularly adults. Reducing environmental stimuli, quiet recovery, and benzodiazepine premedication significantly reduce frequency and severity.

•     Intraocular pressure: Avoid in patients with open globe injuries or conditions sensitive to IOP elevation.

•     Abuse potential: Ketamine is subject to diversion and non-medical use. It is a controlled substance in Kenya under the Pharmacy and Poisons Act.

•     Pregnancy and lactation: Safety has not been established. Use only if potential benefit justifies potential fetal risk. Crosses the placental barrier.

The following interactions are clinically significant. Always inform your healthcare provider of ALL medicines, supplements, and herbal products you are taking.

•     CNS depressants (opioids, benzodiazepines, barbiturates): Enhanced CNS and respiratory depression; dose reduction may be necessary.

•     Thyroid hormones: May cause hypertension and tachycardia.

•     Antihypertensive agents: Blunted cardiovascular stimulation; monitor blood pressure carefully.

Store below 25°C. Protect from light. Do not freeze. Keep in original packaging until use. Diluted solutions should be used immediately after preparation and should not be stored.

Ketamine 50 mg/mL must be stored in a locked, controlled substance cupboard in accordance with Kenyan regulations. Verify prescription validity and prescriber registration before dispensing. The 50 mg/mL concentration may be administered IV without dilution; the 100 mg/mL formulation requires dilution before IV use. Premedication with an anticholinergic and a benzodiazepine is standard practice to reduce adverse emergence effects. Alert prescribers to any concurrent cardiovascular, psychotic, or hepatic conditions. Document dispensing in the controlled drugs register.

Q1: What makes ketamine different from other anaesthetics?

A: Ketamine produces "dissociative anaesthesia", the patient appears conscious (eyes may be open) but is deeply sedated, amnesic, and free from pain. Crucially, it maintains airway reflexes and supports breathing and blood pressure, unlike most other general anaesthetics.

Q2: Can ketamine be used at health centres without a specialist anaesthetist?

A: In Kenya, ketamine is used at secondary and tertiary facilities where staff are trained in its administration and emergency airway management is available. In very remote settings, it may be used by clinical officers trained in procedural anaesthesia following established protocols.

Q3: Why might I feel strange or see things after ketamine?

A: Ketamine can cause "emergence reactions", vivid dreams, hallucinations, or a feeling of unreality as you wake up. These effects are brief and can be minimised by reducing light and noise stimulation, or by giving an additional sedative.

Q4: Is ketamine the same as what is misused recreationally?

A: Yes. Medical-grade ketamine is the same compound misused recreationally as "Special K." For this reason it is a controlled substance in Kenya and is only available under strict prescription and storage controls.

Q5: How quickly does ketamine work?

A: When given IV, anaesthesia is usually achieved within 30 seconds. When given IM, onset takes 3–4 minutes. The effect of a single dose typically lasts 5–25 minutes depending on the dose and route.