How Psychoactive Drugs Affect Us

•Factors that determine effects and abuse potential include:•Route of administration•Speed of transit to the brain•Affinity for nerve cells and neurotransmitters

Routes of Drug Administration and Absorption.5 common ways that drugs enter the body

Routes of Drug Administration and Absorption.

•Inhaling: •Allows the vaporized drug to enter the lungs, the heart and then the brain in about 7-10 seconds (Most rapid)

(Pictures)• Marijuana inhaling tent used by the Scythians, c. 500 B.C.

• Man in India smokes ganja (marijuana) in a “chillum” pipe.

Routes of Drug Administration and Absorption.

•Injecting:(Intravenous)

•Puts drugs directly into a vein

(Intramuscular)

•Put drugs into muscles or under skin

Routes of Drug Administration and Absorption

•Snorting & Mucosal Exposure:• Drugs can be snorted and absorbed through capillaries in the nasal passages or placed on mucosal tissues in the gums, cheeks, or even rectum and absorbed.

•Cocaine snorter’s nose showing how cocaine ate a hole through the nasal septum separating the nostrils.

Routes of Drug Administration and Absorption

•Oral Ingestion:•Drug passes through the esophagus and stomach to the small intestine where it is absorbed by the capillaries lining the walls of the small intestine.

• Hindu ascetic prepares marijuana for drinking.

Routes of Drug Administration and Absorption

Contact or Transdermal Absorption

Absorption through the skin is the slowest method of drug use. It often takes 1–2 days for effects to begin and the absorption can continue for about 7 days. Nicotine, fentanyl, and heart medications can also be absorbed this way

Skin creams & ointments absorbed through skin

Drug Distribution

• Drugs Circulate through the bloodstream to the rest of the body where they cause an effect, be ignored, be absorbed or be biotransformed

• Distribution depends on the drug itself and on blood volume of the person (6-8 quarts in an adult, 3-4 in child)

• Takes 10 to 15 seconds after entering the bloodstream and has the greatest effect on the brain and spinal cord

Drug Distribution: Blood-brain Barrier

• The walls of the capillaries that form a protective shield around the nerves cells of the central nervous system (CNS) and guard against toxins, virus, and bacteria can be penetrated by psychoactive drugs

• Penetration happens because psychoactive drugs are Fat-soulable and the brain and its barrier are fatty

• Psychoactive drugs such as heroin, nicotine, alcohol and marijuana cross this barrier more easily than other substances.

• Cocaine (water soluble) hitchhikes onto protein molecules to pass through blood-brain barrier.

• It takes 1–2 years for the blood-brain barrier to develop fully in infants.

The Nervous System

•Principle Target of Psychoactive drugs

•Network of 100 billion nerve cells & 100 trillion connections

•Nervous System is made up of the:

• Central Nervous System • Peripheral Nervous System

(Somatic & Autonomic)PERIPHERAL

CENTRAL

Reward / Reinforcement Center

•Part of the Brain that encourages a person to remember and repeat an action.

• It is also affected by drugs and is thus responsible for craving

•Drugs act on the reward pathway to trigger craving for euphoria or pain relief

•AKA “mesolimbic dopaminergic reward pathway”

Reward System of the Brain

Neuroanatomy• Nerve cells: Consisting of dendrites, the cell body, the axon and terminals transmit impulses by sending neurochemicals AKA “neurotransmitters” across the synaptic gap between the nerve cells or neurons

• Messages travel in multiple directions but with purpose, enabling the senses to transmit messages to the brain that, in turn, send messages and commands back to the appropriate muscles, tissues, and organs. A single nerve cell can receive signals from hundreds, even thousands of other nerve cells.

Neuroanatomy

•Neurotransmitters move holding sacs in one nerve cell, across the synaptic gap, slot into receptor sites, trigger an impulse, and then move back to the sending cell.

Message Arrives

Neurotransmitters

•The released neurotransmitters cross the synaptic gap and slot into receptor sites on the postsynaptic neuron, causing the retransmission of the message.

•The slotted neurotransmitters are then released and either metabolized in the synaptic gap or more likely reabsorbed through reuptake ports in the sending terminal, ready to be transmitted again.

MessageTransmitted

Neurotransmitters & Receptors

•Psychoactive drugs cannot create sensations or feelings that don’t have a natural counterpart in the body

•So psychoactive drugs duplicate or mimic the natural counterpart in the body to a higher degree

If the cells senses too many neurotransmitters, then it closes down ports.If there is too few neurotransmitters, then the cell opens more ports

•Cocaine forces the release of extra neurotransmitters, especially dopamine, epinephrine, and norepinephrine.

• It then also blocks the reuptake ports so the neurotransmitters cannot be reabsorbed by the sending neuron thus causing excess stimulation of the user.

Cocaine forcesNeurotransmitterRelease

Heroin & Neurotransmitters

• When heroin is taken, it slots into receptor sites on the edge of the pain-transmitting nerve cell, causing a reduction in the amount of substance “P” that gets across the gap.

• The heroin also slots into receptor sites on the receiving neuron, blocking the substance “P” that gets through. When heroin or opioid use is discontinued, the pain returns unless that tissue or organ has been repaired.

Heroin inhibits substance “p”pain message

Agonist & Antagonist

•Drugs disrupt neutral message transmission•Agonist are those drugs that enhance neutral signals mimic or facilitate the effects of neurotransmitters

•Antagonist are those drugs that block neurotransmitters

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Methamphetamine

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Pictures from www.anti-meth.org

Meth Faces

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Meth Faces

Pictures from www.anti-meth.org

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Meth Faces

Pictures from www.anti-meth.org

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Meth MouthUnlike other drugs or vices, methamphetamine seems to be taking a unique and horrific toll inside its users' mouths. In short stretches of time, sometimes just months, a perfectly healthy set of teeth can turn grayish-brown, twist and begin to fall out, and take on a texture less like that of hard enamel and more like a piece of ripened fruit.

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Meth Mouth

Pictures from www.anti-meth.org

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Skin and soft tissue infections are the most frequent cause of hospital admissions among intravenous drug users.

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Skin Abscess

http://img525.imageshack.us/img525/3120/arm2if2.jpg http://vvoice.vo.llnwd.net/e14//the-scourge-of-skid-row.1705518.40.jpg

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Necrotizing Fasciitis (flesh-eating bacteria)

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Necrotizing fasciitis. Sagittal oblique 3D VR CT image

obtained in a 35-year-old man with a history of intravenous drug abuse and necrotizing fasciitis of the right upper extremity shows

extensive débridement of the upper-extremity skin,

subcutaneous tissues, and underlying muscles. The patient

had undergone multiple débridements and a 6-week course

of intravenous antibiotics. The area showed eventual healing by secondary intention, and a skin

graft was not required.

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Krokodil or "Crocodile" in Russian is a homemade substitute of heroin, which is casting deathly shadows over the lives of thousands of Russia's drug addicts. It has a reptilian name because the users' skin starts developing crocodile-like unpleasant scales, over repeated use. And that is arguably the least this deadly drug can do to your body. The scales would give way to decaying sores and gray skin. The flesh would soon start to degenerate and would peel away leaving bones exposed. The users literally rot to death.

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Krokodil

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Alcohol Effects

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Prescription Drug Abuse

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Prescription drugs can transform lives. For the millions of patients who take them, prescription drugs bring dramatic improvements in health and quality of life. But when abused or misused, many of these medications can have effects that disrupt rather than improve lives. Some prescription medications-particularly opioids, central nervous system (CNS) depressants, and stimulants-alter the brain's activity, and misuse or abuse of these drugs can lead to compulsive drug seeking and use, the hallmark of addiction.

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Inhalants

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Inhalants refers to the vapors from toxic substances which are inhaled through the nose and/or mouth to reach a quick high. Of more than 1,000 household and other common products that could be abused as inhalants, most often used are shoe polish, glue, toluene, gasoline, lighter fluid, nitrous oxide or “whippets,” spray paint, correction fluid, cleaning fluid, amyl nitrite or “poppers,” locker room deodorizers or “rush,” and lacquer thinner or other paint solvents.

Most of these produce effects similar to anesthetics, which slow down the body’s functions. After an initial high and loss of inhibition comes drowsiness, light-headedness and agitation.

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