Which of the following anesthetics drug has a higher risk of causing hepatic toxicity ?
A) Propofol
B) Ketamine
C) Isoflurane
D) Nitrous Oxide
The correct answer is C) Isoflurane.
While modern volatile anesthetics are generally much safer than their predecessors, Isoflurane (and other halogenated ethers) carries a higher potential for hepatic (liver) toxicity compared to the other options listed.
Why Isoflurane?
Isoflurane belongs to the class of halogenated inhalation anesthetics.
Immune Response: In some individuals, the immune system recognizes these "altered" proteins as foreign, leading to an inflammatory response and liver damage.
Historical Context: This risk is much lower with Isoflurane than it was with Halothane (the classic cause of "Halothane Hepatitis"), but it remains a known risk factor compared to non-volatile agents like Propofol.
Breakdown of Other Options:
A) Propofol: This is an intravenous (IV) sedative-hypnotic.
B) Ketamine: Primarily known for causing "dissociative anesthesia."
D) Nitrous Oxide: This gas is largely excreted unchanged by the lungs. Its primary toxicity risk is related to the inactivation of Vitamin B12 during prolonged exposure, leading to bone marrow issues or neuropathy, rather than hepatotoxicity.
Key Comparison of Toxicity
| Drug | Primary Toxicity Risk | Target Organ |
| Halothane | Massive Hepatic Necrosis | Liver (Highest Risk) |
| Isoflurane | Mild/Rare Hepatotoxicity | Liver |
| Nitrous Oxide | Vitamin B12 Deficiency | Nerve / Bone Marrow |
| Propofol | PRIS / Bradycardia | Heart / Kidneys |
Drugs may accumulate in the tissues as result of their physicochemical characteristics or special affinity of the tissue for the drug. Which of the following parts of the body does tetracycline accumulate?
A) liver
B) bone
C) muscle
D) adipose tissue
Tetracyclines have a very specific "special affinity" for tissues that are undergoing calcification.
Why Tetracycline Accumulates in Bone
Tetracyclines act as chelating agents. This means they love to bind to multivalent metal ions, specifically Calcium (Ca2+).
The Mechanism: When tetracycline enters the body, it seeks out calcium-rich environments. It forms a stable tetracycline-calcium orthophosphate complex.
The Location: Because bone and teeth are the primary reservoirs of calcium in the body, the drug becomes "trapped" in the hydroxyapatite crystal lattice of these tissues.
The Clinical Consequence: This is why tetracyclines are generally contraindicated (avoided) in:
Pregnant women: It can cross the placenta and affect the skeletal development of the fetus.
Children under 8: It can cause permanent brown/yellow discoloration of the teeth and may temporarily slow bone growth.
Breakdown of Other Tissues and Drug Accumulation:
A) Liver: Many drugs accumulate here because it is the primary site of metabolism, but it isn't the specific "storage" site for tetracycline. Drugs like Chloroquine have a high affinity for the liver.
C) Muscle: While some drugs bind to muscle proteins, it is not a common site for long-term drug sequestration compared to fat or bone.
D) Adipose Tissue (Fat): This is the storage site for highly lipid-soluble (lipophilic) drugs. Classic examples include Thiopental or DDT. Tetracycline is not lipophilic enough to prefer fat over bone.
| Tissue Type | Characteristic | Example Drug |
| Bone / Teeth | High Calcium content | Tetracycline |
| Adipose (Fat) | Lipophilicity | Thiopental |
| Thyroid | Iodine pump | Iodine / Amiodarone |
| Retina | Melanin binding | Chloroquine |
Senna is a widely used stimulant laxative, but when used chronically or in excessive amounts, its active components can lead to liver injury.
The Role of Anthraquinone Glycosides
The active compounds in Senna are known as Sennosides, which belong to a chemical class called anthraquinone glycosides.
How they work: In the colon, bacteria break down these glycosides into active metabolites (like rhein anthrone) that irritate the bowel lining, stimulating movement and water secretion.
Hepatotoxicity: While generally safe for short-term constipation, prolonged or high-dose intake allows these anthraquinone derivatives to be absorbed systemically. Once in the liver, they can cause oxidative stress and damage to hepatocytes (liver cells), leading to "herb-induced liver injury" (HILI).
Breakdown of Other Options:
A) Flavonoid: These are common plant pigments found in many fruits and vegetables. They are generally known for their antioxidant and liver-protective properties rather than being the source of Senna's laxative or toxic effects.
B) Saponins: These are found in plants like ginseng or soy. While they can have toxic effects (like breaking down red blood cells), they are not the active laxative component in Senna.
C) Triterpene: These are precursors to steroids and are found in many medicinal plants, but they do not provide the stimulant laxative action characteristic of Senna.
Clinical Correlation: "Laxative Abuse"
Chronic use of anthraquinone-containing herbs can also lead to a condition called Melanosis Coli, where the lining of the colon turns a dark brown or black color due to pigment deposits. This is often a diagnostic "red flag" for a doctor that a patient has been overusing Senna.
Summary of Senna Pharmacology
| Component | Action | Risk |
| Sennosides A & B | Stimulant Laxative | Dehydration / Electrolyte loss |
| Anthraquinones | Active Metabolite | Hepatotoxicity (with chronic use) |
| Colon Bacteria | Activation of drug | Dependency / Lazy bowel |
To find the total number of units in the vial, we simply need to convert the weight of the drug into milligrams and then multiply by the unit factor.
Let’s calculate step by step:
Amount in vial = 20 grams
Convert grams to milligrams:
Given: 1 mg = 1500 units
Now multiply:
A 31-year-old hypertensive man was treated for addiction to amphetamine. He was also discharged on an antihypertensive drug. Later, he presented with severe depression. Which of the following medications was most likely prescribed?
A) losartan
B) captopril
C) methyldopa
D) hydrochlorothiazide
The correct answer is C) methyldopa.
This question tests your knowledge of the psychiatric side effects of antihypertensive medications. Methyldopa is notorious for causing depressive symptoms, which would be particularly dangerous for a patient already vulnerable due to a history of substance addiction.
Why Methyldopa?
Methyldopa is a centrally acting alpha-2 agonist. While it lowers blood pressure by reducing sympathetic outflow from the brain, it also interferes with the levels of neurotransmitters.
Mechanism of Depression: Methyldopa decreases the concentration of norepinephrine, dopamine, and serotonin in the Central Nervous System (CNS).
The Monoamine Hypothesis: Depression is scientifically linked to a deficiency of these monoamines. By "depleting" these "feel-good" chemicals, methyldopa can induce or worsen severe clinical depression.
Patient Context: For someone recovering from amphetamine addiction, their dopamine system is already in a state of repair. Adding methyldopa can trigger a profound "crash" or depressive episode.
Breakdown of the Other Options:
A) Losartan (ARB): Angiotensin II Receptor Blockers generally do not cross the blood-brain barrier in a way that affects mood. They are "psychiatrically neutral."
B) Captopril (ACE Inhibitor): Similar to Losartan, ACE inhibitors are not typically associated with depression. In fact, some studies suggest they might have a slight mood-elevating effect in some patients.
D) Hydrochlorothiazide (Diuretic): The main side effects of thiazides are related to electrolytes (low potassium, low magnesium) and metabolic issues (high glucose, high uric acid), but not depression.
Clinical "Watch List" for Drug-Induced Depression
In pharmacology exams, three main types of blood pressure medications are frequently linked to depression:
Methyldopa (The most common answer for this type of question).
Reserpine (An older drug that permanently depletes monoamines; rarely used now).
Propranolol (A lipophilic Beta-blocker that can cross into the brain and cause fatigue/depression).
| Drug Class | Example | Psychiatric Side Effect |
| Central Alpha-2 Agonist | Methyldopa | Severe Depression / Sedation |
| Beta-Blockers | Propranolol | Fatigue / Vivid Dreams / Depression |
| Diuretics | Hydrochlorothiazide | No major mood effects |
0 Comments