Drug Interactions between Omnihist II LA and ozanimod

MONITOR: Agents with anticholinergic properties (e.g., sedating antihistamines; antispasmodics; neuroleptics; phenothiazines; skeletal muscle relaxants; tricyclic antidepressants; disopyramide) may have additive effects when used in combination. Excessive parasympatholytic effects may result in paralytic ileus, hyperthermia, heat stroke, and the anticholinergic intoxication syndrome. Peripheral symptoms of intoxication commonly include mydriasis, blurred vision, flushed face, fever, dry skin and mucous membranes, tachycardia, urinary retention, and constipation. Central symptoms may include memory loss, disorientation, incoherence, hallucinations, psychosis, delirium, hyperactivity, twitching or jerking movements, stereotypy, and seizures. Central nervous system-depressant effects may also be additively or synergistically increased when these agents are combined, especially in elderly or debilitated patients. Use of neuroleptics in combination with other neuroleptics or anticholinergic agents may increase the risk of tardive dyskinesia. In addition, some neuroleptics and tricyclic antidepressants may cause prolongation of the QT interval and theoretically, concurrent use of two or more drugs that can cause QT interval prolongation may result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death.

MANAGEMENT: Caution is advised when agents with anticholinergic properties are combined, particularly in the elderly and those with underlying organic brain disease, who tend to be more sensitive to the central anticholinergic effects of these drugs and in whom toxicity symptoms may be easily overlooked. Patients should be advised to notify their physician promptly if they experience potential symptoms of anticholinergic intoxication such as abdominal pain, fever, heat intolerance, blurred vision, confusion, and/or hallucinations. Ambulatory patients should be counseled to avoid activities requiring mental alertness until they know how these agents affect them. A reduction in anticholinergic dosages may be necessary if excessive adverse effects develop.

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MONITOR: The pressor response to phenylephrine may be potentiated by the vagolytic effect of atropine, which inhibits the reflex bradycardia that would normally accompany any increases in blood pressure induced by phenylephrine. Other antimuscarinic agents may also participate in this interaction, although clinical data are lacking. In one report, pseudo-pheochromocytoma (i.e., significant increases in blood pressure and tachycardia) occurred in seven patients who underwent eye surgery and were given phenylephrine 10% ophthalmic solution and systemic atropine, three of whom subsequently developed left ventricular failure and pulmonary edema that required intensive care monitoring. Two patients had preexisting hypertension, while others had no known history of cardiovascular disease. All had received general anesthesia with propofol, phenoperidine, and vecuronium. Since phenylephrine use alone may be associated with cardiovascular toxicities including hypertension, arrhythmia, myocardial infarction and cardiac failure, the extent of involvement by atropine is uncertain. The authors reported no further cardiovascular events following implementation of various measures that reduced phenylephrine dosage and systemic exposure, including: use of a milder strength of phenylephrine ophthalmic solution; swabbing to minimize drainage into the nasolachrymal duct to the nasal mucosa; and use of a cannula to reduce drop size. In a study of six healthy volunteers, diastolic and systolic blood pressure increased by 4 mmHg following administration of phenylephrine (0.42 mcg/kg/min), compared to 17 mmHg when phenylephrine was given after three doses of atropine (0.02, 0.01 and 0.01 mg/kg at 30 minute intervals).

MANAGEMENT: Caution is advised if phenylephrine (systemic or ophthalmic) is used in combination with atropine or other antimuscarinic agents. Cardiovascular status, including blood pressure and heart rate, should be closely monitored. When using ophthalmic formulations, measures to minimize systemic absorption should be employed, such as digital compression of the lacrimal sac or lid closure after instillation. A milder strength (< 10%) is preferable if phenylephrine ophthalmic solution is given.

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GENERALLY AVOID: Coadministration of sympathomimetic agents with drugs that possess monoamine oxidase inhibition (MAOI) activity may precipitate severe hypertensive reactions and hyperpyrexia. Death has occurred in some reported cases. The mechanism involves a synergistic sympathomimetic effect due to enhanced norepinephrine storage in adrenergic neurons secondary to MAOI activity. MAOIs also slow the metabolism of some sympathomimetics such as amphetamines, which may potentiate their effect on the release of norepinephrine and other monoamines from adrenergic nerve endings. Although the interaction has primarily involved nonselective MAOIs, hypertensive crisis has been reported with selective MAO-B inhibitors. Because an active metabolite of ozanimod inhibits MAO-B in vitro, the interaction may theoretically occur with ozanimod. In a placebo-controlled crossover study involving healthy subjects, coadministration of ozanimod with pseudoephedrine did not potentiate the effects on blood pressure; however, ozanimod did increase the pseudoephedrine-induced heart rate response by approximately 3 beats per minute (bpm). In two clinical studies, ozanimod increased systolic pressure by an average of 1 to 2 mmHg over interferon beta-1a, but had no effect on diastolic pressure. The increase in systolic pressure was first detected after approximately 3 months of treatment and persisted throughout treatment. Hypertension was reported as an adverse reaction in 3.9% of patients treated with ozanimod 0.92 mg, compared to 2.1% of patients treated with interferon beta-1a. Two patients treated with ozanimod and one patient treated with interferon beta-1a in these studies experienced a hypertensive crisis.

MANAGEMENT: Until more information is available, concomitant use of ozanimod with sympathomimetic agents should be avoided when possible. Blood pressure and other vitals should be monitored if coadministration is required.

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