Can Desvenlafaxine Be Cut in Half?
No, desvenlafaxine (Pristiq) tablets should not be cut in half. The FDA-approved drug label explicitly states that patients must "swallow desvenlafaxine tablets whole, with fluid" and instructs "do not divide, crush, chew, or dissolve desvenlafaxine tablets" 1.
Why Cutting Is Contraindicated
Desvenlafaxine is formulated as an extended-release tablet that is specifically designed to deliver medication gradually over 24 hours 2, 1. The tablet uses a specialized delivery system where:
- The active medication is absorbed through the tablet matrix over an extended period 2
- After absorption, the empty shell passes through the stool intact—patients may see what looks like a tablet in their stool, which is normal 1
- Cutting, crushing, or chewing the tablet would destroy this extended-release mechanism, potentially causing immediate release of the full dose 1
Clinical Implications of Improper Administration
Disrupting the extended-release formulation can lead to serious consequences:
- Immediate drug dumping could result in higher peak plasma concentrations than intended, increasing risk of adverse effects including nausea, hypertension, and cardiovascular events 2, 1
- Loss of once-daily dosing convenience, as desvenlafaxine's sufficiently long elimination half-life permits single daily dosing only when the extended-release formulation is intact 2
- Increased risk of discontinuation syndrome if the medication is not properly absorbed, as desvenlafaxine requires gradual tapering when discontinued 2, 1
Dosing Alternatives
If dose adjustment is needed, use available tablet strengths rather than splitting:
- The recommended therapeutic dose range is 50-100 mg once daily 1, 3, 4
- Doses above 100 mg/day show no additional therapeutic benefit but significantly increase side effects 5, 6, 3
- For patients requiring lower doses (elderly, renal/hepatic impairment), prescribe the appropriate lower-strength tablet rather than splitting 1, 5
Common Pitfall to Avoid
Do not attempt to split desvenlafaxine tablets to reduce costs or adjust dosing. If a patient cannot afford the prescribed strength or requires dose titration, work with the pharmacy to obtain the appropriate tablet strength rather than instructing patients to split tablets 1.