A nurse is obtaining a medical history from a client who is to start warfarin therapy and currently uses herbal supplements at home. The nurse should inform the client that which of the following herbal supplements can interact adversely with warfarin?

Choice A reason: Bradycardia is not an adverse effect of diphenhydramine. Bradycardia is a slow heart rate, usually below 60 beats per minute. Diphenhydramine is an antihistamine that blocks the effects of histamine, a chemical that causes allergic reactions. Diphenhydramine does not affect the heart rate, although it may cause palpitations or irregular heartbeat in some cases.

Choice B reason: Constipation is an adverse effect of diphenhydramine. Constipation is a condition in which the bowel movements are infrequent, hard, or difficult to pass. Diphenhydramine has anticholinergic properties, which means it inhibits the activity of acetylcholine, a neurotransmitter that regulates the smooth muscle contraction in the gastrointestinal tract. Diphenhydramine can reduce the intestinal motility and cause constipation, as well as dry mouth, blurred vision, and urinary retention.

Choice C reason: Hypertension is not an adverse effect of diphenhydramine. Hypertension is a condition in which the blood pressure is abnormally high, usually above 140/90 mmHg. Diphenhydramine does not affect the blood pressure, although it may cause orthostatic hypotension, which is a sudden drop in blood pressure when changing positions from lying to standing. This can cause dizziness, fainting, or falls.

Choice D reason: Sedation is an adverse effect of diphenhydramine. Sedation is a state of reduced alertness, awareness, or responsiveness. Diphenhydramine can cross the blood-brain barrier and affect the central nervous system, causing drowsiness, fatigue, impaired coordination, and reduced mental performance. Diphenhydramine can also potentiate the effects of alcohol and other sedatives, such as benzodiazepines, opioids, or barbiturates. The nurse should advise the client to avoid driving, operating machinery, or performing other tasks that require attention and concentration while taking diphenhydramine.

Choice A reason: This is incorrect because extravasation is not related to the lifetime cumulative dose limit of doxorubicin, but to the leakage of the medication from the vein into the surrounding tissue. Extravasation can cause severe tissue damage and necrosis, and should be prevented by using a central venous catheter and monitoring the infusion site.

Choice B reason: This is incorrect because red tinged urine and sweat are not related to the lifetime cumulative dose limit of doxorubicin, but to the normal excretion of the medication from the body. Red tinged urine and sweat are expected side effects of doxorubicin and do not indicate toxicity or harm.

Choice C reason: This is correct because an excess amount of doxorubicin can lead to cardiomyopathy, which is a serious and potentially fatal complication of the medication. Cardiomyopathy is a condition in which the heart muscle becomes weak and unable to pump blood effectively. The risk of cardiomyopathy increases with the cumulative lifetime dose of doxorubicin, which should not exceed 450 to 550 mg/m2.

Choice D reason: This is incorrect because myelosuppression is not related to the lifetime cumulative dose limit of doxorubicin, but to the dose-dependent effect of the medication on the bone marrow. Myelosuppression is a condition in which the production of blood cells is reduced, leading to anemia, leukopenia, and thrombocytopenia. Myelosuppression can be managed by adjusting the dose and frequency of doxorubicin and monitoring the blood counts.