Atorvastatin Formulation
No, there are not two clinically distinct "kinds" of atorvastatin—there is one active pharmaceutical ingredient (atorvastatin) that is formulated and marketed as atorvastatin calcium salt. 1, 2, 3
Single Active Pharmaceutical Ingredient
- Atorvastatin is administered clinically as atorvastatin calcium, which is the calcium salt form of the active acid. 3
- The drug is given in its acid form (as the calcium salt), not as separate chemical entities. 4
- Atorvastatin calcium is completely absorbed after oral administration, though it undergoes extensive first-pass metabolism resulting in 14% oral bioavailability. 4
Crystal Form Variations (Not Clinically Relevant "Types")
- Atorvastatin calcium exists in different solid-state forms (polymorphs), including an anhydrous form (Lipitor®) and a trihydrate form (atorvastatin calcium trihydrate, ACT). 5
- The trihydrate form (ACT Form I) was discovered during Phase 3 clinical trials of Lipitor®, after the anhydrous form had already passed Phase I and II trials. 5
- These represent different crystalline structures of the same calcium salt, not different drugs or "kinds" of atorvastatin. 5
- Both forms contain the same active moiety and produce the same therapeutic effects when formulated properly. 5
Clinical Implications
- From a prescribing standpoint, there is only one atorvastatin available in various doses (10,20,40,80 mg tablets). 1
- The drug's metabolism occurs primarily through CYP3A4, with minor contributions from other pathways, regardless of the specific salt form used in manufacturing. 1, 4
- Atorvastatin produces dose-dependent reductions in LDL-cholesterol ranging from 18-55%, with high-intensity dosing (40-80 mg) achieving ≥50% reduction. 1, 2
Manufacturing Context Only
- The distinction between anhydrous and trihydrate forms matters only for pharmaceutical manufacturing, where humidity and temperature can cause phase transitions between hydrate and anhydrate forms. 5
- These solid-state differences affect manufacturing properties (flowability, compressibility) but not the clinical pharmacology once the tablet is administered and dissolved. 5