Salt screening is often used to modify the physicochemical properties of APIs to develop them into acceptable pharmaceutical products. The ultimate goal of salt screening is to select a salt type with good crystallinity, low hygroscopicity and good stability. Our company can provide you with multiple salt screens to improve the solid form characteristics of your APIs. In addition, we can characterize API salt forms through various techniques and evaluate their physicochemical properties, such as solubility, stability and hygroscopicity, so as to help you choose the best API salt. If you have any needs, please feel free to contact us.
Our Service
Generally, the solid-state properties of APIs are not suitable for further drug development. A series of experiments and screenings are usually performed to select the best salt form of the API. The salt formation can improve the physical and chemical properties of drug molecules, such as significantly increasing the solubility and dissolution rate, improve its druggability, improve drug compliance, improve drug stability, and reduce its adverse reactions.
Salt Screening
Salt is typically defined as a chemical compound formed by the reaction of an acid with an alkaline. For alkaline APIs, the most common salt form is hydrochloride, with approximately 60% of all alkaline drug salts being hydrochloride. Hydrochloric acid (HCl) is safe and chlorine is abundant in the body, it is a very cheap option and as it is a strong acid it will form salts with most alkaline compounds. Conversely, for acidic APIs, sodium salt dominates as it is abundant and safe. If the hydrochloride or sodium salt does not work out, there are many other options such as sulfates, phosphoric acid, potassium, calcium salts and so on.
A typical salt screen will involve the following:
1. Choice of acid or alkaline
The key to salt formation studies of APIs is the selection of the acid or alkaline that will form a salt with the APIs, which requires consideration of its pKa value and safety, as well as the route of administration and dosage form after salt formation.
2. Avoidance of the homoiconic effect
If the solvent used for the salt-forming API contains the same ions as the salt, the salt will show a lower solubility and dissolution rate than expected due to the homoiconic effect. Therefore, it is necessary to select an appropriate counterion according to the desired properties.
3. Assess the physical stability of salt
4. Development of a reliable preparation process
5. Scale-up of the selected salt
Characterization of APIs Salts
Determining optimal conditions for salt production using mesostable zone width properties
Measuring thermodynamic solubility in a range of aqueous buffers
Assessing solubility in a variety of biologically relevant media
Conducting long-term stability tests
Forced degradation studies, including light and solution stability assessments
Internal micronization and particle size determination
Our Techniques
| Salt screening | In-situ salt screening technique |
| Salt screening by saturated solution |
| High-throughput salt screening by cooling-evaporative method |
| Characterization of APIs salts | Thermal analysis |
| Microscopy |
| Synchrotron X-ray analysis |
| X-ray powder diffraction |
| NMR |
| High-performance liquid chromatography |
Our Advantages
- Our experienced salt screening team can screen suitable API salts according to your requirements.
- Using various analytical methods such as X-ray powder diffraction, HPLC and NMR, the optimal APIs salts can be quickly screened out.
- We provide you with a one-stop service for salt screening at a reasonable price.
Delivery
| Best salt form for API | Salt screening workflow |
| Physicochemical properties of API salts | Other experimental data |
Please kindly note that our services are for research use only.
