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Providing straightforward information pertaining to drugs, drug use & drug policy. The Grey Pages promotes drug-related literacy and advocates a system of viable and tolerant drug policies. This is my personal collection of commentaries, essays, tid-bits, and other such writings on everything ranging from drug use, drug policy and drug-myths, to drug-science, addiction, human behavior, and the workings of the human brain. I started this blog with a particular focus on opioids, and over the past year have found my interest gravitate toward the intriguing, ever-changing world of designer intoxicants (i.e. "research chemicals" or "designer drugs").

Saturday, March 17, 2012

Barbiturate Vault


General:

Barbiturates are a class of drugs that depress the central nervous system. They are known for their sedative-hypnotic, anxiolytic, anticonvulsant, analgetic, and anaesthetic properties. The name of this class of compounds originates in that they are derivatives of barbituric acid. Though they are largely non-euphorigenic, drugs of this type have a high potential for physical dependence and habituation.

Safety:

Barbiturates are a high-risk drug. Their therapeutic index is slim, meaning there is a narrow margin between the minimally effective therapeutic dose and the toxic or lethal dose. In addition to acute risk factors, barbiturate dependence is characterized by a particularly severe abstinence syndrome upon discontinuation - untreated withdrawal in heavy users is known to cause serious complications and death.

Pharmacology:

Like other depressants, barbiturates target the GABA receptor, specifically the GABA-a-beta subtype. They do not directly agonize GABA receptors, but act as positive allosteric modulators to potentiate GABAergic transmission - in a manner not identical but analogous to benzodiazepines. Barbiturate binding alters the GABA receptor to a conformation with higher affinity for its inhibitory neurotransmitter gamma-amino-butyric-acid. This serves to enhance GABA-activity, leading to reduced communication between neurons. Result being an inhibitory or calming effect on areas of the brain and CNS. Barbiturates also block the AMPA receptor (a subtype of glutamatergic receptor), and therefore inhibit the binding of the excitatory neurotransmitter glutamate.

Though barbiturates target the same receptor type as benzodiazepines and similarly act as positive allosteric modulators for GABA-a, they elicit a cellular response which slightly differs from that of benzodiazepines; Barbiturates increase the amount of time which ion channels of the GABA-a receptor remain opened, increasing the efficacy of GABA; while benzodiazepines cause ion channels to open more frequently, enhancing the potency of GABA. The specific action of barbiturates at this ion channel leads to a greater toxicity compared to benzodiazepines (particularly in cases of overdose).

Use:

Barbiturates were at one time heavily used to treat anxiety and insomnia. They have been largely replaced since the advent of benzodiazepines, which are preferred for their favorable safety profile and lower capacity for producing dependence. They are however still available, but their use is limited mostly to surgical anaesthesia, seizure disorders, severe alcohol & opioid withdrawal, hastening death (i.e. assisted suicide), and execution by lethal injection.

Common Barbiturates, Past or Present Include:

Barbital

Thiopental

Amobarbital

Pentobarbital

Secobarbital

Phenobarbital

Betabarbital

Methohexital

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