Practical Pharmacology

SUBSTANCE ABUSE AND ADDICTION

Substances:
Are chemicals like alcohol, drugs or food.

Substance abuse:

It is intermittent impaired control of substance use and represents a stage in the spectrum of substance use disorders

Tolerance: 

It is a diminished biological or behavioral response to repeated administration of the same amount of a drug; or the need for an increased amount of the drug to achieve the same desired level of effectTolerance reflects the body’s homeostatic adaptations to counter the effects of a drug, there are two types of adaptations:

Cross-tolerance:

Is the decreased pharmacological or behavioral effects of a drug secondary to the use or abuse of a second drug e.g.: alcohol abuse cause cross-tolerance to sedative hypnotics.

Withdrawal (abstinence) syndrome:

It is a syndrome of physical and/or psychological disturbances that follows the abrupt discontinuation of a drug or pharmacological blockage of the actions of a drug

CNS depressants, such as alcohol, barbiturates and opiates have physical withdrawal symptoms such as muscle cramps, nausea, convulsions, and sweating that reflects the compensatory hyperexcitability of the CNS. CNS stimulants, such as cocaine, amphetamine, and nicotine involve a general hypoexcitability of the CNS secondary to withdrawal.


Dependence:
It is persistent drug intake to prevent or diminish the physical or psychological disturbances of withdrawal. Dependence has two components:

Physical dependence: Refers to the physical withdrawal symptoms that occur upon termination of drug use such as, tremor, diarrhea, convulsion, hypnosis, … etc., so persistent drug intake to prevent these symptoms is physical dependence Psychological dependence: Refers to the “ non-physical ” symptoms that occur upon termination of drug use, including: craving, agitation, anxiety, depression …etc.

Addiction:

It is the compulsive use and impaired control of intake of a drug despite its adverse consequences; the most addictive drugs are: Opioids, cocaine, amphetamine, alcohol, and nicotine.

Risk factors of substance abuse:

Genetic vulnerability Environmental factors Pain and self-medications Psychiatric disorders Sociocultural factors

Classification of substances with abuse potential

1- CNS depressants 2- CNS stimulants 3- Hallucinogens 4- Centrally acting anticholinergic drugs 5- Inhalants

CNS depressants

Opioids morphine (natural opiate) heroin (semisynthetic) pethidine (synthetic)

opium poppy(Papaver somniferum)

opium poppy

heroin

CNS depressants
Alcohol ( ethanol) wine vodka whisky beer

Alcohol

CNS depressants
Sedative - Hypnotic drugs Barbiturates (Phenobarbital, secobarbital) Benzodiazepines (diazepam, lorazepam, alprazolam) others (chloral hydrate, meprobamate)

CNS stimulants

Cocaine (coca leaves) Amphetamines (amphetamine, methamphetamine) Nicotine (tobacco) Caffeine (coffee, tea) Cathine (khat)

Coca leaves

Cocaine hydrochloride

Crack cocaine

Hallucinogens

Cannabinoids (marijuana, hashish) Lysergic acid diethylamide (LSD) phencyclidine (PCP) Psilocybin (magic mushroom) Mescaline (hallucinogenic alkaloids)

Cannabis sativa

Cannabis sativa

marijuana

hashish

Centrally acting anticholinergic drugs

Procyclidine (kemadrin) Biperiden (akineton) Benzhexol (artein)

Inhalants(volatile organic compounds)

Aromatic hydrocarbons: Benzene Toluene (methyl benzene Xylene (dimethyl benzene) adhesives, glues, paints, paint thinners

volatile organic compounds

Aliphatic hydrocarbons: - ethane, propane (cigarette lighters) Halogenated hydrocarbons Ethers Ketones: - acetone (nail polish remover)

General effects of substance abuse:

CNS stimulants Mental stimulation, euphoria Hyperactivity, increased sense of energy, increased self-confidence Increased anxiety and easy irritability Decreased appetite (anorexia) Decreased need for sleep (insomnia) Mydriasis , Hyperthermia, Dry mouth, Diaphoresis, Fine tremor, Tachycardia and high blood pressure


CNS depressants Sedation, euphoria Drowsiness and confusion Decreased anxiety Hypnosis, amnesia, and reduced reflex activity (in higher doses) Pupil vary in size (miosis with opioids) Respiratory depression (more obvious with opioids) Weak pulse, bradycardia or tachycardia

Hallucinogens Relaxation, euphoria Confusion, slurred speech Dilated pupils, congested conjunctivae (marked with cannabis} Impairment of skilled motor activity Hallucinations, illusions, depersonalization Time seems to pass slowly, short term memory loss


Inhalants (VOCs) Euphoria, dizziness, disorientation Confusion and impaired judgment (in high doses) Congested conjunctivae, lacrimation Nasotrachial irritation, wheezing Hypotension and tachycardia

Generally the withdrawal signs and symptoms will be opposite to the effects produced by the substance or drug, but also each agent have a characteristic withdrawal syndrome

Consequences and complications of substance abuse:

Acute complications:
Acute overdose Drug interactions Idiosyncratic reaction (mostly with heroin) Body packer syndrome ( rupture of balloons or condoms filled with drugs inside the GIT, occurred in drug smugglers)

Chronic medical consequences

depend on the specific substance and the method of administration

Infections

AIDS & Hepatitis (B&C) in IV drug abusers, due to sharing needles

Psychiatric and behavioral changes

Chronic anxiety Depression Violent behavior, Sleep disorders

Neurological complications

CVA (CNS stimulants) dysarthria ataxia impaired motor skills

Skin

(mostly manifestation of parenteral drug administration)Injection marksMultiple abscesses and ulcers due to infected needlesGranulomatous lesions “popper lesions” in subcutaneous tissue due to injection of insoluble adulterants like starch and talc that acts as foreign bodies

Skin

Hyperpigmentation over veins “turkey skin” which is bluish-black tattooing resulted from carbon deposition by needles sterilized over naked flameCord-like thickening of superficial veins “heroin tracks” due to repeated thrombophlebitisThermal burns in the hands due to repeated lighting or holding hot pipes

Respiratory

(mostly due to smoking and inhalation of substances like tobacco, marijuana, crack cocaine, VOCs ……etc)URTI, LRTI, COPD, lung cancer

ENT Perforation of the nasal septum ( cocaine sniffing) Rhinitis, sinusitis, pharyngitis, laryngitis, cancer Eye Keratitis (crack smoking) Conjunctival ingection (marijuana) CVS HTN, IHD and arrhythmia ( CNS stimulants)

GIT Chronic gastritis, peptic ulcer , liver cirrhosis (alcohol) Genitourinary Impotence and infertility (common with marijuana) STD (sexually transmitted disease), common with cocaine

Thank you