Which of the following statements refers to calcium:

Correct Answer: D

Rationale: The correct answer is D because all the statements are true about calcium. A: The recommended daily allowances for calcium intake vary with age groups. B: Calcium chloride can indeed be irritating and cause necrosis if it leaks out of the vein during intravenous administration. C: Patients with achlorhydria (lack of stomach acid) may have decreased calcium absorption, so calcium carbonate is recommended to be taken with meals or switching to calcium citrate for better absorption. Therefore, choice D encompasses all the correct statements about calcium, making it the correct answer.

Correct Answer: C

Rationale: The correct answer is C: Pseudomembranous colitis. Lincozamides, like clindamycin, can disrupt the normal gut flora, leading to overgrowth of Clostridium difficile and causing pseudomembranous colitis. This condition is characterized by severe diarrhea, abdominal pain, and potentially life-threatening complications. Nephrotoxicity (A) is not a common side effect of lincozamides. Cancerogenity (B) is not associated with lincozamides. Irritation of respiratory organs (D) is not a typical adverse effect of this drug class.

Correct Answer: B

Rationale: The correct answer is B: Penicillin. Penicillin is the drug of choice for syphilis treatment due to its effectiveness in killing the bacteria responsible for syphilis, Treponema pallidum. It is the most recommended treatment by healthcare professionals and is highly effective at curing syphilis at all stages. Gentamycin (A) is not used for syphilis treatment. Chloramphenicol (C) is not effective against Treponema pallidum. Doxycycline (D) is an alternative treatment for syphilis but is not as effective as penicillin, especially in later stages of the disease.

Correct Answer: A

Rationale: The correct answer is A because intravenous acyclovir can cause renal insufficiency due to its nephrotoxic effects. Tremors and delirium are not typically associated with acyclovir. Choice B includes common side effects like rash, diarrhea, and nausea that are not considered unwanted effects. Choice C includes neuropathy and abdominal pain, which are not common unwanted effects of acyclovir infusion. Choice D includes anemia, neutropenia, nausea, and insomnia, which are not typically associated with acyclovir infusion.

Correct Answer: A

Rationale: The correct answer is A: Stroke volume. Digoxin increases myocardial contractility, leading to more forceful contractions and improved cardiac output. This increase in contractility results in a greater ejection fraction and subsequently an increased stroke volume. End-systolic and end-diastolic volumes are not directly affected by digoxin. Systolic pressure may increase due to enhanced contractility, but the primary effect is on stroke volume.