Plant Poisons and Digitalis Effects

Plant Poisons

• Plant poisons are substances derived from plants that induce harmful effects when ingested or contacted.

Digitalis

• Cardiac glycosides, of which digitalis is the most known, have a long history in pharmacology.

• Cardiac glycosides are active compounds in various plants, including:

  • Digitalis purpurea (purple foxglove)
  • Digitalis lanata (white foxglove)
  • Mediterranean sea onion (sea squill)
  • Oleander

• Active principles include Digoxin, Digitoxin, Digitalin, and Digitonin.

• Digoxin is frequently prescribed for congestive heart failure and atrial arrhythmias, available as 0.125 and 0.25 mg tablets.

• Poisoning causes: Accidental (therapeutic overdose, children), or intentional (suicide).

• Mechanism of action (therapeutic dose):

  • Prolongs diastolic period, improving heart filling (negative chronotropic).
  • Enhances systolic power, improving contraction (positive inotropic).
  • Increases renal blood flow.

• Mechanism of action (toxic dose):

  • Cardiac poison.
  • Gastrointestinal (GIT) distress.
  • Visual disturbances.
  • Central nervous system (CNS) symptoms.

• Pathophysiology:

  • Stimulates the vagus nerve (bradycardia).
  • Inhibits Na+-K+ ATPase, leading to:
    • Increased intracellular sodium.
    • Increased intracellular calcium.
    • Increased extracellular potassium (hyperkalemia) in acute toxicity; normally, serum potassium levels are normal or reduced in chronic toxicity due to diuretic therapy.

• Clinical presentation (Cardiac):

  • Arrhythmias are a common manifestation, including both:
    • Tachyarrhythmias (e.g. tachycardia, flutter, fibrillation in atrium and ventricle)
    • Bradyarrhythmias (e.g., sinus bradycardia, AV block, sinus arrest)

• Clinical presentation (Other):

  • Gastrointestinal (GIT): Anorexia, nausea, vomiting, colic, diarrhea.
  • Visual: Green-yellow vision (rods & cones affection).
  • Central Nervous System (CNS): Headache, delirium, disorientation, drowsiness.

• Cause of death: Arrhythmias and cardiac arrest.

• Investigations:

  • ECG and continuous cardiac monitor to detect arrhythmias, heart blocks.
  • Electrolyte levels (hyperkalemia in acute toxicity, hypokalemia, hypercalcemia, hypomagnesmia in chronic toxicity).
  • Kidney function tests (renal impairment affects glycoside elimination).
  • Digoxin levels (therapeutic level is 2 ng/mL; levels above 15 ng/mL are serious).

• Treatment:

  • Prevent further exposure.
  • Supportive measures (e.g., ABCs).
  • Gastrointestinal decontamination (e.g. gastric lavage, charcoal, cholestyramine)
  • Physiological antidote: Digibind (digoxin-specific antibody fragments). Dosage based on total body digoxin load.

Cannabis Sativa

• Cannabis is a psychoactive drug (psychedelic, psychotomimetic, hallucinogen), used medicinally and recreationally.

• Sources: Cannabis sativa, Cannabis indica

• Forms:

  • Hashish: dried resin from flower tops.
  • Hashish oil: dark viscous concentrate of cannabinoids.
  • Bango: from dried leaves.
  • Marijuana: mixture of crushed leaves, flower, and stem.
  • Sinsemilla: 'seedless' mixture of flowering tops and leaves of cultivated female plants .

• Active principle: Delta-9-tetrahydrocannabinol (THC), cannabinol, and cannabidiol. THC is the primary.

• Routes of administration: smoking, ingestion, inhalation; also via tablets (Marinol, dronabinol).

• Pharmacokinetics:

  • Absorption: Inhalation or ingestion; rapid distribution to brain and adipose tissue
  • Metabolism: By liver
  • Excretion: Urine and stool

• Poisoning cause: Accidental overdose.

• Mechanism of action

  • Effects on basal ganglia, cerebral cortex, cerebellum, hippocampus.
  • Stimulates sympathetic receptors and inhibits parasympathetic receptors.
  • Effects vary based on user’s mood, THC concentration, and route of administration.

• Clinical presentation (Mental): Euphoria, sexual/erotic dreams, increased sensory sensitivity (auditory, tactile, olfactory), dysphoria, time and space disorientation

• Clinical presentation (Physical): Dilated pupils, conjunctival congestion, tachycardia, orthostatic hypotension, respiratory depression, increased appetite/dry mouth, urinary frequency

• Cause of death: Central asphyxia, car accidents.

• Investigations: Routine investigations, blood and urine samples for THC.

• Treatment

  • Supportive measures (ABCs; care of respiration).
  • GI decontamination (gastric lavage, charcoal).
  • Symptomatic support if needed (e.g., mild sedation with diazepam).
  • Psychiatric follow-up.

LSD

• Lysergic acid diethylamide (LSD) is an ergot alkaloid.

• Source: Natural: Claviceps purpurea; Synthetic: LSD

• Mechanism of action:

  • Primarily affects the central nervous system (changes in mood and behavior).
  • Affects pyramidal & extrapyramidal systems
  • Affects sympathetic & parasympathetic systems.
  • Has sensory effects

• Clinical presentation (Mental/Physical):

  • Euphoria, laughter, dysphoria, sadness, visual distortions (intense colors, depth perception), auditory, tactile, olfactory, and gustatory hallucinations, alterations in time perception, ego disruption, fear of self-destruction.
  • Physical symptoms such as mydriasis, hyperthermia, piloerection, hyperglycemia, tachycardia, and hypertension.

• Cause of death: Suicide.

• Management:

  • Provide a quiet, lighted environment.
  • Reassurance.
  • Sedation/Tranquilization (e.g., Diazepam, Chloropromazine).

Drug Dependence

• Definitions:

  • Drug of abuse: The use (oral, smoking, etc.) of a substance to alter mood or state of consciousness.
  • Substance of abuse: Usage for non-medical reasons, to achieve a state of well-being, or avoid discomfort – often condemned by society.
  • Drug habituation: A desire to take drug without compulsion.
  • Drug addiction/dependence: Compulsive and repeated drug use resulting in physical and psychological dependence.

• Mechanism of drug dependence:

  • Cellular adaptation (neuronal or receptor changes) to the presence of the drug.
  • Interruption or decrease in drug administration leading to disturbed cellular function.

• Characteristics of dependence:

  • Compulsive desire for drug.
  • Tolerance.
  • Physical dependence.
  • Psychological dependence.
  • Withdrawal symptoms.
  • Detrimental effects on the individual, family, and society.

• Methods of abuse of addicting drugs:

  • Nasal insufflation (e.g., heroin).
  • Inhalation (e.g., cocaine).
  • Smoking (e.g., hashish).
  • Intravenous injection (e.g., morphine).
  • Dissolving tabs then intravenous injection

• Types of addicts:

  • Therapeutic.
  • Professional.
  • Street.
  • Congenital.