In 1970's the people used Intravenous saline water with barbiturates & paralytic .
But now in most states three separate injections (in sequential order) are used :
1. Sodium thiopental: ultra-short action barbiturate, an anaesthetic agent capable of rendering the offender unconscious in a few seconds.
2. Pancuronium: non-depolarizing muscle relaxant, causes complete, fast and sustained paralysis of the skeletal striated muscles, including the diaphragm and the rest of the respiratory muscles; this would eventually cause death by asphyxiation.
3. Potassium chloride: stops the heart, and thus causes death by cardiac arrest.
The drugs are not mixed externally as that can cause them to precipitate
All states and the federal government use lethal injection as their primary method of execution. Some states use a three-drug protocol, others use a single-drug process. The three-drug protocol uses an anesthetic, followed by pancuronium bromide to paralyze the inmate and potassium chloride to stop the inmate's heart. The one-drug protocol uses a lethal dose of an anesthetic.
intravenous bolus, a relatively large dose of medication administered into a vein in a short period, usually within 1 to 30 minutes. The IV bolus is commonly used when rapid administration of a medication is needed, such as in an emergency; when drugs that cannot be diluted, such as many cancer chemotherapeutic drugs, are administered; and when the therapeutic purpose is to achieve a peak drug level in the bloodstream of