Why is Pregnancy a Contraindication?
Enalapril can cause significant harm or death to a developing fetus, particularly during the second and third trimesters. The risks include:
↪Renal Failure: It interferes with the development of the fetal kidneys.
↪Oligohydramnios: A decrease in amniotic fluid, which can lead to limb contractures and craniofacial deformation.
↪Hypoplasia: Underdevelopment of the lungs and skull bones.
| Condition | Enalapril Usage |
| Pregnancy | Strictly Contraindicated (Teratogenic) |
| Hypertension | Standard First-line Treatment |
| Diabetes | Recommended (Protects kidneys) |
| Heart Failure | Recommended (Improves survival rates) |
Which of the following drugs is considered as an enzyme inhibitor that may effect the metabolism of other drugs?
A)phenytoin
B)furosemide
C)cimetidine
D)theophylline
The correct answer is C) cimetidine.
Cimetidine is a classic example of a potent hepatic enzyme inhibitor. Specifically, it inhibits several isoenzymes of the cytochrome P450 (CYP450) system in the liver.
Why Cimetidine?
When an enzyme inhibitor like cimetidine is present, it "clogs up" the metabolic machinery. This means other drugs that rely on those same enzymes to be broken down will stay in the body longer, potentially reaching toxic levels.
Breakdown of the Options
Cimetidine (Inhibitor): Known for numerous drug interactions. It can increase the levels of drugs like warfarin, phenytoin, and theophylline, making them dangerous.
Phenytoin (Inducer): This is actually the opposite. It is an enzyme inducer, meaning it speeds up metabolism, often making other drugs less effective.
Furosemide (Diuretic): This is a "loop diuretic" used for fluid retention. While it has its own side effects, it is not categorized as a primary CYP450 enzyme inhibitor.
Theophylline (Substrate): This is a bronchodilator with a narrow therapeutic index. It is usually the victim of enzyme inhibitors (like cimetidine), which can cause theophylline levels to rise to toxic points.
Common Enzyme Inhibitors (The "SICKFACES.COM" Mnemonic)
To help remember the most common inhibitors in pharmacology, students often use this acronym:
S - Sulfonamides
I - Isoniazid
C - Cimetidine
K - Ketoconazole
F - Fluconazole
A - Alcohol (Acute use)
C - Ciprofloxacin
E - Erythromycin
S - Sodium Valproate
C - Chloramphenicol
O - Omeprazole
M - Metronidazole
Which of the following is the content of a monophasic contraceptive ?
A)constant dose of estrogen
B)variable dose of progesterone
C)constant dose estrogen and progesterone
D)variable doses of estrogen and progesterone
The correct answer is C) constant dose of estrogen and progesterone.
In a monophasic oral contraceptive, every active pill in the pack contains the exact same amount of both estrogen (usually ethinyl estradiol) and a progestin (progesterone).
Understanding the "Phases"
Contraceptives are classified based on how the hormone levels change throughout the 21 active days of the pill cycle:
↪Monophasic (Constant/Constant): Every active pill is identical. This provides a steady level of hormones, which often results in fewer side effects related to hormone fluctuations.
↪Biphasic: The estrogen stays the same, but the progesterone dose increases halfway through the active cycle.
↪Triphasic: The doses of estrogen, progesterone, or both change every 7 days (three distinct phases) to more closely mimic a natural menstrual cycle.
Mechanism of Action
Regardless of whether they are monophasic or multiphasic, these "combined" pills work through three primary methods:
↪Inhibition of Ovulation: They suppress the release of FSH and LH from the pituitary gland, preventing the egg from being released.
↪Thickening Cervical Mucus: This makes it physically difficult for sperm to enter the uterus.
↪Thinning the Endometrium: This alters the lining of the uterus, making it less receptive to implantation.
| Type | Estrogen Dose | Progesterone Dose |
| Monophasic | Constant | Constant |
| Biphasic | Constant | Increases once |
| Triphasic | Variable | Variable |
Which of the following is the best classification for Bisoprolol?
A) beta 1 adrenergic receptor agonist
B) beta 1 adrenergic receptor blocker
C) alpha 1 adrenergic receptor blocker
D) non-selective beta adrenergic receptor blocker
The correct answer is B) beta 1 adrenergic receptor blocker.
Bisoprolol is a highly cardio-selective beta_1 receptor antagonist. In the world of pharmacology, "selective" means it has a much higher affinity for the receptors located in the heart than those in the lungs or blood vessels.
Why Bisoprolol is Classified This Way:
Targeting the Heart (𝛃1): 𝛃1 receptors are primarily located in the heart. By blocking these, Bisoprolol decreases heart rate and the force of contraction, which lowers blood pressure and reduces the heart's oxygen demand.
Sparing the Lungs (𝛃2): Unlike non-selective blockers (like Propranolol), Bisoprolol at standard doses avoids blocking 𝛃2 receptors in the lungs. This makes it a safer choice for patients with respiratory issues like asthma or COPD.
Breaking Down the Other Options:
A) beta agonist: This would stimulate the heart (like Dobutamine), increasing heart rate and blood pressure—the exact opposite of what Bisoprolol does.
C) alpha blocker: These drugs (like Prazosin or Doxazosin) work primarily by dilating blood vessels rather than acting directly on the heart's beta receptors.
D) Non-selective beta blocker: This category includes drugs like Propranolol or Nadolol, which block both 𝛃1 and 𝛃2 receptors.
Clinical Significance of Selectivity
Physicians choose Bisoprolol specifically when they want to treat cardiovascular conditions without causing significant peripheral or pulmonary side effects.
| Drug Generation | Selectivity | Examples |
| 1st Gen (Non-selective) | 𝛃1 + 𝛃2 | Propranolol, Sotalol |
| 2nd Gen (Selective) | 𝛃1 only | Bisoprolol, Atenolol, Metoprolol |
| 3rd Gen (Vasodilatory) | Variable + 𝜶1 | Carvedilol, Labetalol |
Which of the following fetal adverse effects are seen with the use of finasteride during pregnancy?
A)growth restrictions
B)genital abnormality
C)neural tube defects
D)placental abruptions
The correct answer is B) genital abnormality.
Finasteride is a specific 5-alpha reductase inhibitor. Its mechanism of action and its contraindication in pregnancy are tied directly to the development of the male fetus.
Why Genital Abnormalities Occur
Finasteride works by blocking the enzyme 5-alpha reductase, which is responsible for converting testosterone into the more potent androgen, Dihydrotestosterone (DHT).
During fetal development, DHT is strictly required for the normal "masculinization" of male external genitalia. If a pregnant person is exposed to finasteride:
👉It inhibits the production of DHT in the male fetus.
Unique Handling Precautions
Because finasteride can be absorbed through the skin, the clinical warnings for this drug are quite unique:
Category X: It is strictly contraindicated in pregnancy.
Handling Warning: Women who are pregnant or may potentially be pregnant should not even handle crushed or broken tablets of finasteride, as skin absorption alone can provide enough of the drug to cause these fetal abnormalities.
Summary of Other Options
✖A) Growth restrictions: While many drugs cause IUGR (Intrauterine Growth Restriction), it is not the hallmark side effect of 5-alpha reductase inhibitors.
✖C) Neural tube defects: These are typically associated with Folic Acid deficiency or drugs like Valproate (anti-epileptic).
✖D) Placental abruptions: This is usually a mechanical or vascular complication associated with conditions like severe hypertension or cocaine use, not hormonal inhibition.
Clinical Note
Finasteride is commonly used for Benign Prostatic Hyperplasia (BPH) and Male Pattern Baldness (Androgenetic Alopecia). Because it targets the DHT pathway, it effectively shrinks the prostate and slows hair loss, but those same hormonal pathways are vital for a developing baby.
Which of the following is the mode of action of Phentolamine?
A) beta-adrenergic blocker
B) beta-adrenergic agonist
C)alpha-adrenergic agonist
D)alpha-adrenergic blocker (non selective alpha blocker)
The correct answer is D) alpha-adrenergic blocker (non selective alpha blocker).
Phentolamine is a competitive, non-selective alpha-adrenoceptor antagonist. This means it blocks both 𝛂1 and 𝛂2 receptors with roughly equal affinity.
Mechanism of Action
By blocking these receptors, phentolamine prevents the binding of norepinephrine and epinephrine, leading to the following physiological effects:
𝛂1 Blockade: Causes vasodilation of the blood vessels. Since 𝛂1 receptors normally mediate vasoconstriction, blocking them leads to a significant drop in peripheral vascular resistance and blood pressure.
𝛂2 Blockade: Blocks the "negative feedback loop" on the presynaptic nerve terminal. This causes an increased release of norepinephrine, which can lead to reflex tachycardia (a rapid heart rate) as the excess norepinephrine stimulates beta_1 receptors in the heart.
Clinical Uses
Because of its potent vasodilatory effects, Phentolamine is primarily used in specific medical emergencies:
Pheochromocytoma: To manage hypertensive crises caused by the sudden release of catecholamines from a tumor of the adrenal medulla.
Extravasation: It is injected locally if a vasoconstrictor (like norepinephrine or dopamine) accidentally leaks out of the vein into the surrounding tissue, preventing local necrosis (tissue death).
Cocaine-Induced Hypertension: To counteract the severe alpha-mediated vasoconstriction caused by cocaine.
| Drug | Selectivity | Primary Use |
| Phentolamine | Non-selective (𝛂1 = 𝛂2) | Hypertensive emergencies / Extravasation |
| Phenoxybenzamine | Non-selective (Irreversible) | Pre-operative pheochromocytoma |
| Prazosin | Selective 𝛂1 | Chronic hypertension / BPH |
| Yohimbine | Selective 𝛂2 | Research / (Historically) Erectile dysfunction |
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