According to the US Pharmacopeia, select the most common type/s of chemical reactions that cause most drugs to lose stability. Select all that apply
Photolysis
Oxidation-Reduction
Hydrolysis
Epimerization
Isomerization
Correct Answer : B,C
Drug stability refers to the capacity of a pharmaceutical formulation to remain within defined physical, chemical, and microbiological specifications. Chemical degradation typically involves the breaking or forming of covalent bonds, leading to a loss of potency or the formation of toxic byproducts. Environmental factors like temperature, moisture, and pH act as catalysts for these kinetic processes. Understanding these reactions is essential for determining expiration dates and storage requirements.
Rationale:
A. Photolysis is a degradation process triggered by the absorption of radiant energy or light. While significant for light-sensitive drugs like nitroprusside or nifedipine, it is not considered one of the two "most common" general pathways for the majority of pharmaceuticals. It requires specific chromophores to occur. Most drugs are primarily susceptible to moisture or oxygen before photo-degradation occurs.
B. Oxidation-Reduction (redox) reactions involve the transfer of electrons and are a primary cause of drug instability. Many medications, particularly those with phenolic or ethereal functional groups, are highly sensitive to atmospheric oxygen. This process often leads to color changes and the production of free radicals. It is a dominant pathway for chemical degradation in many liquid and solid dosage forms.
C. Hydrolysis is arguably the most common cause of drug instability, involving the cleavage of chemical bonds by water. Functional groups such as esters, amides, and lactams are particularly vulnerable to nucleophilic attack by water molecules. Since many drugs are stored in environments with humidity or formulated as aqueous solutions, hydrolysis is a constant threat to molecular integrity. It remains a critical concern in pharmacopoeial standards.
D. Epimerization is a specific type of degradation where a molecule shifts the configuration of a single chiral center. While clinically relevant for drugs like tetracycline, where it leads to a loss of activity, it is a specialized reaction. It is not categorized by the USP as a universal mechanism of instability compared to hydrolysis. Its occurrence is limited to specific stereochemical structures.
E. Isomerization involves the conversion of a drug into its optical or geometric isomer. Similar to epimerization, this results in a change in pharmacological activity but is not a ubiquitous degradation pathway. Most pharmaceutical instability issues across the broad spectrum of drug classes are rooted in redox or hydrolytic processes. Isomerization remains a secondary, less frequent concern in general stability testing.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
Subcutaneous mycoses are fungal infections that involve the dermis, subcutaneous tissues, and sometimes the underlying bone. They usually result from the traumatic inoculation of fungi found in soil or decaying vegetation into the skin. These infections are localized and typically do not disseminate to distant organs. Because these fungi grow slowly and evade the immune system effectively, the resulting lesions develop over many months or years.
Rationale:
A. Chronic and insidious is the correct description of the clinical course. These infections, such as sporotrichosis or mycetoma, progress very slowly over time. Patients often ignore the initial painless nodules, leading to a long duration of infection before seeking medical help. This persistent progression is a hallmark of fungal pathogens that inhabit deeper skin layers.
B. "Balignant" (likely a typo for malignant) and untreatable is incorrect. While these infections can be disfiguring and difficult to manage, they are not cancerous (malignant). Most subcutaneous mycoses can be treated with long-term antifungal therapy or surgical debridement, although the treatment duration may last for several months to successfully clear the organism.
C. Benign and treatable is only partially correct. While they are "benign" in a non-cancerous sense, the medical definition of benign often implies a self-limiting or harmless nature. Subcutaneous infections are destructive and can lead to significant tissue loss or secondary infections. They are treatable, but the course is often complex and far from "simple."
D. Acute and symptom-free is incorrect because these infections are explicitly not acute. An acute infection appears suddenly and resolves quickly, whereas subcutaneous mycoses are long-standing. Furthermore, they are not symptom-free; they present with ulcerations, abscesses, and draining sinus tracts that are clinically evident upon physical examination.
Correct Answer is A
Explanation
Lactulose is a synthetic disaccharide consisting of galactose and fructose that remains unabsorbed in the small intestine. It functions as an osmotic agent, drawing water into the colonic lumen to soften stool and stimulate peristalsis. Additionally, it is used to manage hepatic encephalopathy by acidifying the gut and converting ammonia to unabsorbable ammonium ions. It is a vital medication for both gastrointestinal and hepatic disorders.
Rationale:
A. Laxative is the correct therapeutic class. Specifically, lactulose is an osmotic laxative. By increasing the osmotic pressure in the colon, it promotes fluid retention and increases bowel motility. It is commonly used for chronic constipation and is particularly effective when a soft stool is required to prevent straining during defecation in high-risk cardiac or surgical patients.
B. Antidepressants are medications used to treat mood disorders by modulating neurotransmitters like serotonin and norepinephrine. Lactulose has no pharmacological activity in the central nervous system related to mood regulation. It does not cross the blood-brain barrier in significant amounts and lacks affinity for monoamine transporters. Therefore, it has no utility in treating clinical depression.
C. Antipsychotics are used to manage symptoms of schizophrenia and bipolar disorder by blocking dopamine receptors. Lactulose is a sugar derivative that stays within the gastrointestinal tract and does not interact with dopaminergic pathways. Its therapeutic effects are restricted to osmotic and acid-base changes in the bowel, rendering it useless for the management of psychosis or hallucinations.
D. Antidiabetics are agents that lower blood glucose levels, such as metformin or insulin. Despite being a disaccharide, lactulose is not absorbed and therefore does not raise or lower serum glucose significantly. It is not used to treat hyperglycemia; in fact, diabetic patients must use it with caution as small amounts of free sugars may be present in the solution.
Whether you are a student looking to ace your exams or a practicing nurse seeking to enhance your expertise , our nursing education contents will empower you with the confidence and competence to make a difference in the lives of patients and become a respected leader in the healthcare field.
Visit Naxlex, invest in your future and unlock endless possibilities with our unparalleled nursing education contents today
Report Wrong Answer on the Current Question
Do you disagree with the answer? If yes, what is your expected answer? Explain.
Kindly be descriptive with the issue you are facing.