Ketamine dosage is largely affected by the weight of the recipient, by whether the drug is being administered intravenously or intramuscularly, and by age. In adults, 1 milligram (mg) of ketamine per pound (0.45 kg) in weight will provide between five and 10 minutes of anesthesia, suitable for performing surgery. If the drug is administered intramuscularly, 5 mg per pound in weight will generally put the patient into surgical anesthesia for between 12 and 25 minutes. To maintain anesthesia, smaller ketamine doses such as 0.1 to 0.5 mg per minute can be administered on a drip.
Ketamine is used as an anesthetic in surgical operations where the skeletal muscles do not have to be relaxed. Sometimes the drug is combined with other substances such as diazepam, but this cannot be done in the same syringe. The psychological effect of the drug is reduced by combining ketamine with diazepam. Ketamine can cause side effects such as nausea, vomiting, confusion, blurred vision and mood changes.
Weight is the main factor that affects ketamine dosage, and the dosages are usually supplied according to weight, rather than by a basic adult dosage. This is simply because more of the drug is required to anesthetize patients who are heavier. Other factors can affect the recommended dosage of ketamine, however, and intravenous ketamine dosage can range from 0.5 mg to 2 mg per pound.
The method of administration is another key factor in determining the correct ketamine dosage. If the drug is to be administered intramuscularly, then the dosage must be around 5 mg per pound of weight for 12 to 25 minutes of anesthesia. As with the intravenous administration, this can also change depending on the physician’s recommendation. Generally, intramuscular administrations of ketamine should be between 3 and 6 milligrams per pound.
The age of the patient is one other factor which can affect ketamine dosage. Ketamine must be administered slowly. Generally it is advised that intravenous ketamine be administered through a period of around one minute to avoid possible side effects such as respiratory depression. After the dose has been administered, the drug acts quickly. In an ordinary 1 mg per pound intravenous ketamine dosage, anesthesia will occur in around 30 seconds.