Thiopental sodium is administered intravenously as :
**Core Concept**
Thiopental sodium is a barbiturate-based anesthetic agent used for inducing general anesthesia. Its pharmacological action is primarily through the modulation of neuronal activity in the central nervous system (CNS).
**Why the Correct Answer is Right**
Thiopental sodium acts by enhancing the inhibitory neurotransmission mediated by GABA (gamma-aminobutyric acid), the principal inhibitory neurotransmitter in the CNS. This is achieved through the binding of thiopental to the GABA_A receptor, a ligand-gated chloride channel. The binding of thiopental to the receptor increases the frequency of opening of the chloride channel, leading to an influx of chloride ions into the neuron, which hyperpolarizes the membrane and reduces neuronal excitability. This results in a rapid onset of sedation and unconsciousness.
**Why Each Wrong Option is Incorrect**
**Option A:** Thiopental sodium is not administered orally because its rapid onset of action requires a rapid increase in blood concentration, which is not feasible with oral administration.
**Option B:** Thiopental sodium is not administered intraarterially because it is not necessary to deliver the anesthetic directly to the arterial system for its intended effect.
**Option C:** Thiopental sodium is not administered intraperitoneally because it is not necessary to deliver the anesthetic directly into the peritoneal cavity for its intended effect.
**Clinical Pearl / High-Yield Fact**
Thiopental sodium is a highly lipid-soluble anesthetic agent, which allows it to rapidly cross the blood-brain barrier and induce unconsciousness within 15-30 seconds of administration. This rapid onset of action makes it an ideal choice for induction of general anesthesia.
**Correct Answer: C. Intravenously**