Psychopharmacology Exam 3 Study Guide

Sedative-Hypnotic and Anxiolytic Medications: Historical Background

Ever wondered how people managed anxiety before modern medicine? In the 19th century, doctors prescribed bromide and chloral hydrate as sleep-inducing agents. Then came barbiturates (or "barbs") like phenobarbital, which were widely used but had serious safety issues.

By the 1950s, carbamates like meprobamate (Equanil, Miltown) emerged as anxiety treatments, and carisoprodol (Soma) as muscle relaxers. Unfortunately, these weren't any safer than barbiturates.

The 1960s brought a major breakthrough with benzodiazepines (benzos). Starting with chlordiazepoxide (Librium), these medications quickly became popular, with familiar names like diazepam (Valium), alprazolam (Xanax), clonazepam (Klonopin), and lorazepam (Ativan).

Quick Fact: Both barbiturates and benzodiazepines work by binding to GABA receptors in the brain's limbic system, creating an overall sedative effect.

Neurobiology of Anxiety and Sedatives

Your brain has specific regions that control fear and anxiety. The amygdala, OFC, and insula are key players in your anxiety response. When something's wrong with these areas, anxiety disorders can develop - PET scans show increased blood flow in the amygdala during anxiety, and MRI scans reveal abnormalities in people with panic disorder.

GABA (gamma-aminobutyric acid) is the star neurotransmitter here. When GABA doesn't work properly, your amygdala becomes overly sensitive, making you anxious about things that shouldn't be stressful. Benzodiazepines help "reset" your amygdala to respond normally.

Barbiturates produce several effects beyond just making you sleepy. They suppress REM sleep and impair cognitive functions like memory and judgment. While they don't relieve pain (they're not analgesics), they do produce alcohol-like effects on behavior.

Warning: Barbiturates have a high overdose risk, making them dangerous for both accidental overdose and suicide attempts.

Barbiturates: Clinical Use and Risks

Barbiturates have largely fallen out of favor in modern medicine, and for good reasons. They have a narrow therapeutic window - meaning the difference between an effective dose and a lethal dose is dangerously small.

These medications develop tolerance in two main ways: your liver starts breaking them down faster (enzyme induction), and your neurons adapt to their presence. This means you need more of the drug to get the same effect over time.

Physical dependence is a serious concern with barbiturates. Even normal prescribed doses can lead to dependence, and withdrawal from high doses can trigger psychosis. This makes them risky for people with a history of substance abuse.

Important note: Pregnant women taking barbiturates as anti-epileptic drugs (AEDs) should use the lowest effective dose possible, as these medications may cause developmental issues.

Common barbiturates include phenobarbital (for seizures, insomnia, and anxiety), secobarbital (Seconal), amobarbital (Amytal), and pentobarbital (Nembutal) - some of which are now primarily used for animal euthanasia.

From Barbiturates to Benzodiazepines

Since the 1960s, benzodiazepines have largely replaced barbiturates as the go-to medications for anxiety. They quickly became synonymous with terms like "tranquilizer" and "anxiolytic," and are now among the most commonly prescribed psychotropic drugs.

Benzos offer significant advantages over older medications - they work immediately, unlike antidepressants (SSRIs) which take weeks to become effective. However, they come with their own risks - dependence occurs in about 10% of users, and that rate jumps to 34% in people with depression.

Many patients prefer benzos because they provide immediate relief. While cognitive behavioral therapy (CBT) may be more effective in the long run, it often takes months to see results. The instant relief benzos provide makes them attractive despite their risks.

Reality Check: Benzodiazepines offer quick anxiety relief, but their potential for dependence means they're typically prescribed for short-term use only.

Benzodiazepine Risks and Side Effects

Benzodiazepines pose special risks for older adults. Seniors have reduced ability to metabolize these drugs, leading to stronger and longer-lasting effects. This increases their risk of falls, hip fractures, and can worsen dementia and depression.

The way benzos work is by enhancing GABA's inhibitory effects in your brain. This produces several effects: sedation (feeling calm and sleepy), anxiolysis (reduced anxiety), some anticonvulsant action (for seizures), and cognitive and psychomotor inhibition (slowed thinking and movement).

Common side effects include excessive sedation, ataxia (loss of coordination), lethargy, impaired thinking, and amnesia. Physical and psychological dependence is a serious concern, especially for people with substance use disorders. Benzos also dangerously interact with alcohol and other sedatives.

Safety Alert: High doses of benzodiazepines during pregnancy can cause "floppy infant syndrome," where babies are born dependent on the drug and experience withdrawal symptoms.

Benzodiazepines and Related Medications

Common benzodiazepines you might recognize include diazepam (Valium), alprazolam (Xanax), triazolam (Halcion), lorazepam (Ativan), and clonazepam (Klonopin). Each has slightly different properties that make them suitable for different conditions.

Beyond traditional benzos, there are medications called Benzodiazepine Receptor Agonists (BZRAs) or "hypnotics." These drugs activate the same receptors as benzos but have different chemical structures. They're mainly prescribed for insomnia and have limited use as anti-epileptic drugs.

The popular "Z Drugs" fall into this category. Zolpidem (Ambien) is widely prescribed for insomnia but can cause daytime impairment and is concerning for older adults. These medications can create amnesia-like states where people appear awake but have no memory of their actions.

Did you know? Some people taking hypnotic medications have reported "sleep driving" - driving a car while in a drug-induced amnestic state - along with other complex behaviors like making phone calls or preparing food with no memory of doing so.

Z-Drugs and Anesthetics

Among the "Z drugs," zaleplon (Sonata) induces rapid sleep with fewer lingering effects. It's unlikely to cause dependence and only has abuse potential at extremely high doses. Eszopiclone (Lunesta) has more prolonged action, making it better for maintaining sleep throughout the night.

Sleep-related activities while on these medications can be dangerous. The FDA has issued advisories about sleep driving and other complex behaviors performed while in a drug-induced amnestic state - you're technically awake but have no memory afterward.

Anesthetics are another important class of GABA-activating drugs. These include ultrashort-acting barbiturates like thiopental (Pentothal), as well as propofol (Diprovan) and etomidate (Amidate). They take effect immediately but have little analgesic (pain-relieving) or euphoric activity.

Chemistry Connection: Many general anesthetics used in surgery, like isoflurane and sevoflurane, are administered through inhalation and work by depressing the central nervous system to produce unconsciousness.

Anxiolytics Beyond Benzodiazepines

Not all anxiety medications work on GABA. Some researchers believe anxiety may result partly from serotonin $5-HT$ deficits, which is why SSRIs (selective serotonin reuptake inhibitors) are now first-choice drugs for many anxiety disorders, despite taking weeks to become effective.

Buspirone (BuSpar) represents a unique approach to treating anxiety. As a selective 5-HT1A agonist approved in 1986 for Generalized Anxiety Disorder (GAD), it works differently than benzos. It causes minimal sedation, doesn't impair memory or coordination, and doesn't interact dangerously with other sedatives.

What makes buspirone special is its low addiction potential. It doesn't substitute for benzodiazepines in dependent individuals and has no cross-tolerance with them. It also has some antidepressant effects, though it works gradually rather than immediately and won't help with sleep issues.

Patient Benefit: Buspirone offers anxiety relief without the risks of dependence and cognitive impairment that come with benzodiazepines, making it a good option for long-term anxiety management.

Cannabis and the Endocannabinoid System

Let's switch gears to discuss cannabis. While "marijuana" is a commonly used term, it has roots in racism and social stigma. Scientists prefer terms like cannabis (the plant genus), cannabinoids (compounds found in the plant), and endocannabinoids (natural neurotransmitters in our brains).

Your brain has specific cannabinoid receptors - CB1 in the central nervous system and CB2 in the immune system. These are G-protein coupled receptors similar in number to those for GABA and glutamate. The primary endocannabinoid neurotransmitter is anandamide.

THC (delta-9 tetrahydrocannabinol) is the main psychoactive ingredient in cannabis. Its effects vary depending on how it's administered - whether inhaled (smoked or vaped), ingested (edibles), or absorbed (tinctures, sublingual products). The amount that reaches your brain depends on both potency and dose.

Science Fact: Your body actually produces its own cannabinoid-like chemicals (endocannabinoids) that play important roles in regulating mood, memory, appetite, and pain sensation.

Cannabis: Effects and Impacts

The effects of cannabis vary widely depending on dose, how you use it, your personal experience, individual vulnerability, and your environment. Many users report positive effects like increased well-being, euphoria, relaxation, reduced anxiety, enhanced senses, and altered time perception.

However, cannabis can also cause negative effects, particularly in inexperienced users. Anxiety and paranoia sometimes occur, possibly related to increased heart rate. The drug impairs coordination and reaction time, making activities like driving dangerous even after the high seems to fade.

Cognitive impairment is another concern - cannabis affects memory, attention, and motivation. Physically, it increases heart rate and dilates some blood vessels while constricting arteries in the brain. The dilated blood vessels in the eyes create the classic "bloodshot" appearance.

Safety Reminder: Driving under the influence of cannabis is dangerous and illegal in most places, even if you feel the effects have worn off. THC can impair coordination and reaction time for hours after use.