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by Maria Carvalho, PharmD, MRPharmS, PhD, Manager of PCCA Science (R&D) and Yi Liu, PharmD, PhD, RPh, PCCA Research Pharmacist
Our new, patent-pending base — SuspendIt Anhydrous — is an innovative anhydrous suspension vehicle that offers improved physical characteristics, broader application and the potential for longer default beyond use dates (BUDs). It is ideal for active pharmaceutical ingredients (APIs) that are unstable in water or have incompatibilities with existing aqueous vehicles.
We performed multiple tests, including evaluation of SuspendIt Anhydrous’ sedimentation properties, its self-emulsifying drug delivery system and compatibility with nasogastric feeling tubes, as summarized below.
A unique physical characteristic of SuspendIt Anhydrous is its improved viscosity, which reduces when shaken and thickens when standing. The improved viscosity allows for rapid redispersion of APIs with agitation and minimizes sedimentation. Sedimentation is the simple process in which suspended particles separate from a liquid and, due to gravity, settle on the bottom of a container.
In one of three studies, we evaluated and compared the sedimentation properties of SuspendIt Anhydrous to the performance of two competitor products (Product A and Product B) using an enrofloxacin 100 mg/mL anhydrous suspension (raspberry flavor, pink color). The suspensions were placed in a standing position at room temperature for 30 days. On day 28, the glass containers were shaken vigorously with the same amount of force and duration and allowed to settle again. By day 29 (after redispersion on day 28), SuspendIt Anhydrous remained a homogenous suspension with no signs of separation (Figures 1 – 3).
What makes our new base particularly unique is its self-emulsifying drug delivery system (SEDDS). The system creates a spontaneous emulsion when SuspendIt Anhydrous comes into contact with water or other liquids, creating a uniform emulsion that is characterized by small and homogenous droplets.
In one of two studies, we conducted a microscopic evaluation of droplet size formation for metronidazole 50 mg/mL anhydrous suspension prepared using SuspendIt Anhydrous (left) and Product B (right). When the samples were observed under the microscope at 4x magnification, the suspension using the PCCA SuspendIt Anhydrous showed a homogeneous dispersion (Figure 2). Product B displayed aggregation of metronidazole (Figure 3, highlighted with arrow) and separation of the water and oily phases (Figure 4, highlighted with arrow).
Figures 2-4.Microscopic evaluation of droplet size formation (4x objective lens) for metronidazole 50 mg/mL anhydrous suspension prepared using SuspendIt Anhydrous (left) and Product B (right).
The SEDDS in SuspendIt Anhydrous allows for the formation of a uniform emulsion, characterized by small and homogeneous droplets. As a result, the self-emulsifying properties of SuspendIt Anhydrous are likely to promote increased drug solubility, dispersibility, absorption and bioavailability.
Nasogastric feeding tubes are commonly used in patients when enteral nutrition is required. However, tube clogging remains a significant barrier to the delivery of drug and nutritional support — attention must always be paid to this potential complication. It is also essential that drug administered via a nasogastric tube preserves the correct API dose when exiting from the tube.
In one of several of studies, we evaluated the likelihood of compounded anhydrous suspensions (metronidazole 50 mg/mL, tretinoin 10 mg/mL or nifedipine 4 mg/mL) to block or leave residues in nasogastric feeding tubes. The resulting volume was measured; potency testing was determined by HPLC. Results indicated the amount of metronidazole, tretinoin or nifedipine recovered from the feeding tubes was >95% for SuspendIt Anhydrous.
Figure 1. Note how the SuspendIt Anhydrous formulation flows freely and does not cause clumping or blockage. Click the image to watch the video.
On the day after the recovery test, we observed that there were no significant drug residues throughout the nasogastric tube, nor at the exit of the tube, for the oral suspensions in SuspendIt Anhydrous (Figure 2). On the contrary, there was visible accumulation of drug residues for the corresponding Product A and Product B oral suspensions, which suggests potential tube clogging (Figures 3 and 4).
Figures 2-4. Nasogastric feeding tubes (exit) on the day after the recovery test for the metronidazole oral suspensions in PCCA SuspendIt Anhydrous and the corresponding Product A and Product B products.
To view details of the multiple studies conducted using SuspendIt Anhydrous, PCCA members can access the complete Science Manual on our Members-Only Website. PCCA members also have access to formulas developed for SuspendIt Anhydrous, including stability studies. Members with clinical services may contact our Clinical Services Team for help with formulas and other compounding concerns.