A patient receiving Morphine for postoperative pain relief displays slow, shallow breathing with a rate of 8 breaths/minute. The nurse recognizes this as a side effect called:

Choice A reason: This is incorrect. Antibiotics are not a term for a drug model, but a class of drugs that are used to treat bacterial infections. Antibiotics can have different chemical structures, mechanisms of action, and modes of action. For example, penicillin is a prototype drug of the beta lactam antibiotics, which inhibit the synthesis of bacterial cell walls¹.

Choice B reason: This is incorrect. Pharmacologic drug is not a term for a drug model, but a general term for any substance that has a physiological effect on the body. Pharmacologic drugs can belong to different classes, such as analgesics, antihistamines, or antivirals. For example, aspirin is a prototype drug of the nonsteroidal anti-inflammatory drugs (NSAIDs), which reduce pain, inflammation, and fever.

Choice C reason: This is correct. Prototype drug is the term used for a well understood drug model with which other drugs in its representative class are compared. A prototype drug is an individual drug that has similar chemical structure, mechanism of action, and mode of action as other drugs in its class. A prototype drug is often the first developed or the most important drug in its class, and is used as a reference for comparison. For example, morphine is a prototype drug of the opioid analgesics, which relieve pain by binding to opioid receptors in the brain and spinal cord.

Choice D reason: This is incorrect. Therapeutic drug is not a term for a drug model, but a term for any drug that is used to treat or prevent a disease or disorder. Therapeutic drugs can belong to different classes, such as antibiotics, antihypertensives, or antidepressants. For example, metformin is a prototype drug of the biguanide antidiabetic drugs, which lower blood glucose levels by reducing glucose production in the liver and increasing glucose uptake in the muscles.

Choice A reason: Vasodilation is not the primary therapeutic effect of atropine in this scenario. Atropine is a medication that blocks the action of acetylcholine, a neurotransmitter that stimulates the parasympathetic nervous system. Atropine can cause vasodilation by inhibiting the muscarinic receptors on the blood vessels, which normally cause vasoconstriction. However, this effect is not significant or consistent, and it does not improve the symptoms of bradycardia, which is a slow heart rate that can cause dizziness, fatigue, or fainting. The nurse should monitor the blood pressure and the peripheral pulses of the patient after administering atropine.

Choice B reason: Bronchodilation is not the primary therapeutic effect of atropine in this scenario. Atropine is a medication that blocks the action of acetylcholine, a neurotransmitter that stimulates the parasympathetic nervous system. Atropine can cause bronchodilation by inhibiting the muscarinic receptors on the bronchial smooth muscle, which normally cause bronchoconstriction. However, this effect is not relevant or beneficial for the patient with symptomatic bradycardia, who does not have any respiratory problems. The nurse should assess the respiratory rate and the breath sounds of the patient after administering atropine.

Choice C reason: Increase in heart rate is the primary therapeutic effect of atropine in this scenario. Atropine is a medication that blocks the action of acetylcholine, a neurotransmitter that stimulates the parasympathetic nervous system. Atropine can increase the heart rate by inhibiting the muscarinic receptors on the sinoatrial node and the atrioventricular node, which normally slow down the heart rate. This effect is desirable and beneficial for the patient with symptomatic bradycardia, who has a slow heart rate that can cause dizziness, fatigue, or fainting. The nurse should monitor the electrocardiogram and the heart rate of the patient after administering atropine.

Choice D reason: Diuresis is not the primary therapeutic effect of atropine in this scenario. Atropine is a medication that blocks the action of acetylcholine, a neurotransmitter that stimulates the parasympathetic nervous system. Atropine can cause diuresis by inhibiting the muscarinic receptors on the bladder, which normally promote urination. However, this effect is not important or helpful for the patient with symptomatic bradycardia, who does not have any urinary problems. The nurse should measure the urine output and the specific gravity of the patient after administering atropine.