Drugs

Learning objectives What is drug misuse and drug abuse? What is addiction? Understand basic ideas about how drugs may influence transmission of action potentials from pre-synaptic neuron to post-synaptic neuron. You do NOT need to memorize the individual effects of each of the drugs. You SHOULD be able to understand and explain such statements as “Drug X blocks the serotonin re-uptake protein on the pre-synaptic neuron”. What are some effects of stimulants? What are some effects of depressants? What are some effects of cannabinoids? What is the active ingredient of marijuana?

Drug (ab)use

Drug use and misuse and abuse Prescription drugs used for other purposes Abuse Use of drugs in an amount, a situation or a manner that causes problems or increases risk of problems

Dependence and Addiction Dependence – Physiological – Body relies on the drug in order to avoid withdrawal Addiction – Uncontrollable cravings, inability to control drug use (or behavior) despite doing harm to oneself and others

Stimulants Cocaine (and crack) Amphetamines (Adderall) Methylphenydate (Ritalin, Concerta) Methamphetamine (meth) MDMA (ecstasy, also hallucinogenic) Bath salts Caffeine

Action of depressants Depressants increase binding of GABA, which enhances GABA’s inhibitory effect

Increased dopamine release by this neuron THC GABA usually reduces amount of dopamine released THC binds (and blocks) GABA. Post-synaptic neuron releases more dopamine in next step Increased dopamine release by this neuron

Opioids (Narcotics) Mimics endorphin (endogenous morphine) Depresses some parts of the brain Stimulate other parts, including reward pathways Opioids – general term that includes: Heroin, morphine, hydrocodone, oxycodone, fentanyl, methadone, codein, thebaine

Opioids Primary action of opioids Pathways affected Opioids affect ion balance in pre-synaptic cell, preventing neurotransmitter release. Pathways affected Brain Activates reward system (leads to addiction) Brainstem Depresses respiration (often the cause of death in overdoses) Spinal chord Dampens transmission of pain-related signals Intestines Reduces peristalsis, causing constipation

Opioids Overdose treatment Naloxone (Narcan) Acts very quickly Binds to opioid receptors Prevents binding by opioids Acts very quickly

Opiate withdrawal Initial Withdrawal symptoms Muscle aches and spasms Trouble sleeping Racing heart Sweating Anxiety Yawning Hypertension Fever agitation

Opioid detox Medical Behavioral therapies Methadone (Dolophine, Methadose) and Buprenorphine (Subutex) Stimulate opioid pathways Dampened ‘high’ Reduce withdrawal symptoms Naltrexone (Depade, Revia) Blocks action of opioids Prevents getting high Long-acting formulations (Vivitrol) administered once per month Compliance often difficult because no high is created Behavioral therapies Contingency management – rewards for negative drug tests Cognitive-behavior therapy – increase skills to cope with life stressors

LSD activates serotonin receptors MDMA causes excessive serotonin and dopamine release PCP affects many neurotransmitter systems Affects region of brain dealing with perception. May include mixing senses (‘hearing’ colors and ‘seeing’ sounds) ‘Trips’ may be pleasurable or a ‘bad trip’ may include terrifying thoughts or nightmares Some are addictive (PCP, MDMA) Some are not (LSD) Some users develop chronic mental disorders