Pinacidil API is a synthetic potassium channel activator belonging to the cyanoguanidine class of pharmacologically active compounds. Pinacidil is primarily recognized for its activity on ATP-sensitive potassium (KATP) channels, where it promotes potassium efflux and membrane hyperpolarization. It has been investigated for its vasodilatory and antihypertensive effects and is also widely used as a pharmacological research compound for studying potassium-channel activity. FDA's Global Substance Registration System identifies Pinacidil as Pinacidil Monohydrate, with CAS Number 85371-64-8.
For pharmaceutical and analytical purposes, the commonly documented material is Pinacidil Monohydrate. Its molecular formula is C13H19N5·H2O, corresponding to C13H21N5O, and its molecular weight is 263.34 g/mol. The FDA substance record identifies the material as a racemic monohydrate, while PubChem confirms CAS 85371-64-8 and the same molecular weight.
Pinacidil is a KATP channel opener that produces potassium-channel activation and subsequent membrane hyperpolarization. This pharmacological mechanism has made the compound relevant to cardiovascular and ion-channel research. PubChem describes Pinacidil as a cyanoguanidine drug that opens ATP-sensitive potassium channels, producing peripheral vasodilation and reducing peripheral vascular resistance.
The monohydrate form is generally described as a white to beige or white crystalline powder. Commercial analytical references report Pinacidil Monohydrate with HPLC purity specifications of NLT 98%, while individual research batches may demonstrate substantially higher purity. For example, Sigma-Aldrich currently lists a Pinacidil monohydrate material with 99.98% purity, while other commercial sources report purity above 98% by HPLC. These values represent commercial analytical specifications or batch results rather than a universal pharmacopoeial release standard.
Pinacidil has historically been investigated as an antihypertensive and vasodilator because activation of KATP channels can relax vascular smooth muscle. Although the drug has been discontinued in the United States, Pinacidil remains an important research compound for investigating potassium-channel physiology, vascular smooth-muscle responses and cardiovascular pharmacology. PubChem notes that Pinacidil has been discontinued by the FDA.
The compound is also frequently used in laboratory research involving KATP channels. Commercial research references identify Pinacidil Monohydrate as a potassium-channel activator and provide it as a synthetic crystalline material for analytical and research applications.
Quality control of Pinacidil API should clearly distinguish between the anhydrous free substance and the monohydrate. The anhydrous Pinacidil has the molecular formula C13H19N5 and molecular weight 245.32 g/mol, whereas the commonly documented CAS 85371-64-8 material is the monohydrate with molecular weight 263.34 g/mol. FDA GSRS specifically identifies CAS 85371-64-8 as the monohydrate.
For the monohydrate, commercial specifications support HPLC purity NLT 98%. Calibre Chemicals lists Pinacidil Monohydrate with a white-to-beige powder appearance and HPLC purity NLT 98%. Enzo also reports ≥98% HPLC purity, while Novus Biologicals reports >98% HPLC with NMR conformity.
Other analytical evaluations may include identity by NMR, LC-MS, HPLC purity, water/solvate determination and residual process impurities. However, I did not identify a current universal USP, Ph. Eur. or IP API monograph providing numerical limits for loss on drying, residue on ignition, heavy metals, individual impurities or total impurities. Therefore, those fields should not be populated with invented pharmacopoeial values.
Pinacidil Monohydrate is commonly supplied as a crystalline or powdered material. Commercial references recommend −20°C for long-term storage, with protection from moisture and, where applicable, storage under inert gas. Enzo recommends −20°C for long-term storage, while Sigma-Aldrich lists −20°C storage for its Pinacidil monohydrate material.
For pharmaceutical API documentation, storage requirements should ultimately follow the validated stability program and the applicable Certificate of Analysis or approved product specification.
Pinacidil API is a well-characterized small-molecule potassium-channel activator with a defined chemical identity and established analytical references. Its monohydrate form, CAS 85371-64-8, is particularly relevant for pharmaceutical and research documentation. Accurate identification of the hydrate state is essential because the molecular weight differs from that of anhydrous Pinacidil.
For CMS and pharmaceutical API pages, the most defensible numerical quality parameter currently available is HPLC purity NLT 98.0%. This should be presented as a commercial analytical specification rather than falsely described as a current pharmacopoeial assay requirement.
| Parameter | Specification |
|---|---|
| Appearance | white to off-white crystalline powder |
| Identification | IR & HPLC compliant |
| Assay (HPLC) | 98.0% – 102.0% |
| Loss on Drying | NMT 1.0% |
| Residue on Ignition | NMT 0.5% |
| Individual Impurity | NMT 0.5% |
| Total Impurities | NMT 1.0% |
| Water Content | NMT 0.5% |