I take hydroxyzine pamoate 25mg and now my doctor prescribed hydroxyzine hcl 50mg. What is the difference besides the mg?
This is a little tricky. Yes, both formulations have the same active ingredient (hydroxyzine), BUT they are attached to 2 DIFFERENT salt forms (Hcl which is found in the tablet form, and under the brand name "Atarax" vs. pamoate which is found in the capsule form, and under the brand name "Vistaril"). The pamoate formulation is more lipophilic, which means it can more easily cross the blood brain barrier and exhibit Central Nervous System effects such as anti-anxiety effects. The Hcl formulation is more hydrophilic, which means theoretically there should be less CNS effects. Both formulations are antihistamines due to the hydroxyzine part, which acts similar to cetirizine (Zyrtec) for itching, hives, etc. However, there are no studies performed to show the Clinical Signifigance (i.e. Can this theory be proven in practice and does it matter?) because these are old drugs that no drug company would want to spend hundreds of thousands of dollars testing, when there is no benefit (profit-wise) if the theory is true. So, yes, there is a difference between hydroxyzine hcl and hydroxyzine pamoate, but we don't know if the difference matters clinically since it's a waste of money to try and figure that out.
- Hydroxyzine Information for Consumers
- Hydroxyzine Information for Healthcare Professionals (includes dosage details)
- Side Effects of Hydroxyzine (detailed)
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