Which of the following is true of selective toxicity?
1) It refers to the process of determining the correct dose of a particular drug
2) To be effective, an antimicrobial agent must be more toxic to the patient than the pathogen
3) It contributes to antibiotic resistance
4) It refers to the body’s ability to protect the brain and eye
5) It takes advantage of metabolic and structural differences between host and pathogen
The correct answer and explanation is :
The correct answer is:
5) It takes advantage of metabolic and structural differences between host and pathogen.
Explanation:
Selective toxicity is a fundamental principle of antimicrobial therapy. It refers to the ability of a drug to target and kill or inhibit the growth of microbial pathogens while causing minimal or no harm to the host. This principle is based on the idea that there are significant structural and metabolic differences between pathogens (such as bacteria, fungi, or viruses) and human cells.
For example, antibiotics like penicillin specifically target peptidoglycan, a component of bacterial cell walls that human cells lack. Similarly, antifungal drugs like fluconazole interfere with ergosterol synthesis, a key component of fungal cell membranes that is absent in human cells.
Why the Other Options Are Incorrect:
1) Incorrect – Selective toxicity is not about determining the correct dose of a drug. While dosage is important, selective toxicity refers to how the drug differentiates between host and pathogen.
2) Incorrect – The antimicrobial agent must be more toxic to the pathogen than the patient, not the other way around. Otherwise, it would be unsafe for medical use.
3) Incorrect – While antibiotic resistance is a serious issue, it is not directly caused by selective toxicity. Resistance occurs due to genetic changes in pathogens, not because of the drug’s selective targeting.
4) Incorrect – The blood-brain barrier protects the brain and eyes, but this is not related to selective toxicity.
Conclusion:
Selective toxicity is a key feature of effective antimicrobial therapy, ensuring that drugs effectively eliminate pathogens while preserving the health of the patient.