Tetracaine

As with all anesthetics, the dosage varies and depends upon the area to be anesthetized, the number of neuronal segments to be blocked, individual tolerance, and the technique of anesthesia. The lowest dosage needed to provide effective anesthesia should be administered. For specific techniques and procedures, refer to standard textbooks.

Suggested Dosage for Spinal Anesthesia Using 1% Tetracaine HCl Injection, USP

* For vaginal delivery (saddle block), from 2 mg to 5 mg in dextrose.

† Doses exceeding 15 mg are rarely required and should be used only in exceptional cases. Inject solution at rate of about 1 mL per 5 seconds.

Extent of Dose of solution Volume of spinal fluid Site of injection Anesthesia (mL) (mL) (lumbar interspace) Perineum 0.5 (= 5 mg)* 0.5 4th Perineum and 1.0 (= 10 mg) 1.0 3rd or 4th lower extremities Up to costal 1.5 to 2.0 1.5 to 2.0 2nd, 3rd, or 4th margin(= 15 mg to 20 mg)†

The extent and degree of spinal anesthesia depend upon dosage, specific gravity of the anesthetic solution, volume of solution used, force of the injection, level of puncture, position of the patient during and immediately after injection, etc.

When spinal fluid is added to 1% tetracaine hydrochloride injection, some turbidity results, the degree depending on the pH of the spinal fluid, the temperature of the solution during mixing, as well as the amount of drug and diluent employed. Liberation of base (which is completed within the spinal canal) is held to be essential for satisfactory results with any spinal anesthetic.

The specific gravity of spinal fluid at 25°C/25°C varies under normal conditions from 1.0063 to 1.0075. The 1% concentration in saline solution has a specific gravity of 1.0060 to 1.0074 at 25°C/25°C.

A hyperbaric solution may be prepared by mixing equal volumes of the 1% solution and Dextrose Solution 10%.

Examine ampules carefully before use. Do not use solution if crystals, cloudiness, or discoloration is observed.

This formulation of tetracaine hydrochloride does not contain antimicrobial or bacteriostatic agents; therefore, unused portions should be discarded.

Sterilization of Ampules

The tetracaine hydrochloride injection is sterile within an undamaged ampule. To destroy bacteria on the exterior of ampules use heat sterilization (autoclaving) before opening. Immersion in antiseptic solution is not recommended.

Autoclave at 15-pounds pressure, at 121°C (250°F), for 15 minutes.

Autoclaving increases likelihood of crystal formation. Unused autoclaved ampules should be discarded. Under no circumstances should unused ampules which have been autoclaved be returned to stock.