The drug penetration tester is a precision device used to measure the softness and hardness of semi-solid preparations such as ointments, suppositories, and eye ointments. The core principle is to allow a standard cone (with a mass of 100g ± 0.1g) to freely penetrate the sample within a specified temperature (such as 25 ℃) and time (5 seconds), and quantify the consistency of the material by measuring the penetration depth (unit: 0.1mm, which is one cone penetration unit). For example, if the cone penetration of Vaseline is 200, it means that the cone penetration depth is 20.0mm - the smaller the value, the harder the material; The larger the value, the softer the texture.
R&D stage: "Hardness ruler" for formula optimization
In the development of ointments, if the target cone penetration is 250-300 (such as erythromycin ointment), the measuring instrument can assist in screening the matrix ratio: when the ratio of Vaseline to Lanolin is 8:2, if the cone penetration is only 180, liquid paraffin needs to be added to adjust to the target range to ensure that the application is neither "too hard to push away" nor "too soft to flow easily".
The cone penetration of suppositories directly affects the convenience of insertion: for example, the ideal cone penetration of ibuprofen suppositories is 150-200, but if it is only 100 (hard) in actual testing, it may lead to difficulties in medication for patients; If it reaches 250 (too soft), it is prone to deformation during storage, and the measuring instrument can guide the adjustment of the ratio of polyethylene glycol and glycerol stearate.
Production process: real-time monitoring of process stability
During the cooling process of the eye ointment, if the cone penetration measurement value drops sharply from 300 to 200 (within 10 minutes), it may indicate that the matrix crystallization is too fast, and the stirring rate or cooling temperature needs to be adjusted to avoid uneven texture of the eye ointment;
If the content of the soft capsule is semi-solid ointment, it is necessary to ensure a cone penetration of 180-220 before filling. Otherwise, the capsule may rupture due to being too hard, or the content may leak due to being too soft. The measuring instrument can complete rapid detection within 5 minutes before filling.
Quality Inspection and Compliance: The "Rigid Execution Tool" of Pharmacopoeia Standards
The penetration rate of medicinal Vaseline cone should be between 130-230 (25 ℃, 100g cone);
The cone penetration of the vaginal plug should be controlled within 100-200 degrees, while that of the vaginal plug should be 150-250 degrees to adapt to the physiological characteristics of different cavities;
The Chinese Pharmacopoeia clearly stipulates that:
In the stability test, if the cone penetration of a certain ointment drops from 280 to 220 after being stored at 40 ℃ for 3 months, it indicates that the matrix may undergo a phase change and the shelf life needs to be shortened or the packaging material needs to be optimized.
| Instrument type |
working principle |
Typical application scenarios |
performance advantage |
| Manual Cone Penetrometer |
Manually release the cone and read the penetration depth through the dial, requiring manual timing (e.g. 5 seconds). |
Laboratory basic testing, teaching demonstration |
Low cost, suitable for samples with a wide range of viscosity changes (such as paste) |
| Automatic Cone Penetrometer |
Electronic control of cone release and timing, built-in sensor for real-time recording of penetration depth, with an accuracy of ± 0.5 units. |
Quality inspection departments and R&D centers of pharmaceutical companies |
Reduce human error and store over 1000 sets of data |
| Constant temperature cone penetrometer |
Equipped with a water bath or constant temperature chamber (temperature control accuracy ± 0.5 ℃) to ensure testing is conducted at standard temperature. |
Temperature sensitive preparations (such as thermosensitive gel) |
Eliminate the impact of temperature fluctuations on the results (for every 1 ℃ increase in temperature, cone penetration may increase by 5-10 units) |
| Multi functional rheometer integration |
By attaching cone plate accessories, cone penetration data can be synchronously obtained while measuring rheological properties (such as viscosity). |
Complex matrix formulations (such as self emulsifying ointments) |
Multidimensional analysis of material characteristics to reduce sample waste |
The 'optimizer' for patient experience：
If the penetration of topical corticosteroid ointment is too low (such as<180), the patient needs to rub vigorously when applying, which may cause skin irritation; If it is too high (>300), it is easy to contaminate clothing. The measuring instrument precisely controls the hardness, making the ointment "soft but not collapsing, hard but not stiff", and improving medication compliance.
The 'booster' of production efficiency：
After the introduction of an online cone penetration monitoring system in a certain suppository production line, the batch failure rate was reduced from 12% to 2%. The reason is that when the cone penetration deviates from the target value due to temperature fluctuations during material transportation (such as from 180 to 220), the system automatically triggers heating compensation to avoid scrapping the entire batch of suppositories.
The 'technical backing' of innovative dosage forms：
For new thermosensitive in situ gel (such as ophthalmic drug delivery systems), the cone penetration should be 250~300 at room temperature (convenient for eye drops), and drop to 50~80 when the temperature rises to 37 ℃ after entering the eye (forming gel retention). The tester provides key data support for the development of such "temperature hardness" responsive preparations.
AI prediction modelBy collecting over 100000 sets of cone penetration and formula data, some instruments can train algorithms to automatically recommend matrix ratios after inputting target cone penetration values (such as Vaseline: liquid paraffin=7:3 cone penetration can reach 250), shortening the research and development cycle by more than 50%.
Portable on-site inspectionHandheld cone penetrometer (with a range of 50~500 and an accuracy of ± 2 units) has been used for sampling in pharmaceutical warehouses, without the need to send samples back to the laboratory. It can determine whether the texture of the ointment to be stored meets the standard within 1 minute.
Linkage production systemThe cone penetration tester can be integrated with MES (Manufacturing Execution System) to automatically upload data to the cloud for each batch of samples tested, generating trend charts (such as automatic warning when the standard deviation of cone penetration is greater than 5 for 10 consecutive batches), helping pharmaceutical companies achieve quality traceability and process optimization.
From ancient pharmacists using "finger pressure" to determine the softness and hardness of ointments, to today's cone penetration testers quantifying texture with an accuracy of 0.1mm, these devices have witnessed the transformation of semi-solid preparations from "empirical preparation" to "precise and intelligent manufacturing". It is like a "hardness balance" for formulations, defining the application experience of each ointment with numbers, providing traceable scientific basis for the comfort of suppository insertion and the eye retention of eye ointment - in the invisible microscopic world, every cone penetration value is an important footnote to safeguard the safety and efficacy of medication.