July 27, 2016
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Discontinued Warning IconPlease Note: This Brand Name drug is no longer available in the US.
(Generic versions may still be available.)



Pentothal (Thiopental Sodium for Injection, USP) is an ultrashort-acting depressant of the central nervous system which induces hypnosis and anesthesia, but not analgesia. It produces hypnosis within 30 to 40 seconds of intravenous injection. Recovery after a small dose is rapid, with some somnolence and retrograde amnesia. Repeated intravenous doses lead to prolonged anesthesia because fatty tissues act as a reservoir; they accumulate Pentothal (thiopental sodium) in concentrations 6 to 12 times greater than the plasma concentration, and then release the drug slowly to cause prolonged anesthesia.

The half-life of the elimination phase after a single intravenous dose is three to eight hours.

The distribution and fate of Pentothal (thiopental sodium) (as with other barbiturates) is influenced chiefly by its lipid solubility (partition coefficient), protein binding and extent of ionization. Pentothal (thiopental sodium) has a partition coefficient of 580.

Approximately 80% of the drug in the blood is bound to plasma protein. Pentothal (thiopental sodium) is largely degraded in the liver and to a smaller extent in other tissues, especially the kidney and brain. It has a pKa of 7.4.

Concentration in spinal fluid is slightly less than in the plasma.

Biotransformation products of thiopental are pharmacologically inactive and mostly excreted in the urine.

Diluents in Pentothal (thiopental sodium) ® Kits

Ready-To-Mix Syringes and Vials
(For preparing solutions of Thiopental Sodium for Injection, USP)

Sterile Water for Injection, USP serves only as a pharmaceutic aid for diluting or dissolving drugs prior to administration.

Water is an essential constituent of all body tissues and accounts for approximately 70% of total body weight. Average normal adult daily requirement ranges from two to three liters (1.0 to 1.5 liters each for insensible water loss by perspiration and urine excretion).

Water balance is maintained by various regulatory mechanisms. Water distribution depends primarily on the concentration of dissociated electrolytes in the body compartments and sodium (Na+) plays a major role in maintaining a physiologic equilibrium between fluid intake and output.

0.9% Sodium Chloride Injection, USP serves only as an isotonic vehicle for drugs prior to administration.

Sodium chloride in water is an electrolyte solution of sodium (Na+) and chloride (Cl-) ions. These ions are normal constituents of the body fluids (principally extracellular) and are essential for maintaining electrolyte balance.

The distribution and excretion of sodium (Na+) and chloride (Cl-) are largely under the control of the kidney which maintains a balance between intake and output of these ions.

The small volumes of fluid and amounts of sodium chloride provided by 0.9% Sodium Chloride Injection in Ready-to-Mix Syringes are unlikely to produce a significant effect on fluid or electrolyte balance.

Last reviewed on RxList: 12/8/2004
This monograph has been modified to include the generic and brand name in many instances.

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