When Carbopol 940 is an anionic adhesive, it cannot be used in combination with divalent basic drugs to avoid precipitation. The bioadhesive drug delivery system (BDDS) acts on the epidermal cell mucosa or skin surface of various cavities, such as the gastrointestinal tract, vagina, oral cavity, nasal cavity, epidermis, etc. The dosage forms include tablets, films, gels doses, sticks, etc. Among them, gel is a new type of bioadhesive drug delivery system that has developed rapidly in recent years. It has good dispersibility, strong adhesion, good stability, long-lasting efficacy, convenient application, and can avoid first-pass effect and administration site. Advantages of high concentration.
1) Gastrointestinal bioadhesives
The sulpiride matrix sustained-release retention tablet made of Carbopol 940 can adhere to the surface of gastrointestinal mucin or epithelial cells to prolong the retention time and achieve the purpose of sustained release. In vivo studies in rabbits show that compared with oral solution and powder injection, the AUC of the sustained-release retention tablet can be increased by more than 1 times, the mean retention time (MRT) can be prolonged by 4 to 5 times, and the bioavailability is improved.
2) Vaginal bioadhesives
Gel of metronidazole liposomes and clotrimazole liposomes with carbomer 974NF in the treatment of vaginitis. The in vitro test showed that about 50% metronidazole and 30% clotrimazole remained in the gels after the two drug-containing liposome gels were released for 24 hours. And the stability test showed that carbomer 974NF could maintain two kinds of liposome particle size distribution, indicating that the bioadhesive liposome gel is suitable for local treatment of vaginal diseases. In order to avoid the removal of the uterus in patients with uterine cancer, the preparation based on Carbopol 940 can be administered through the vagina to make the drug adhere to the uterine mucosa, kill cancer cells without damaging normal cells, and avoid removal of the uterus.
Using an appropriate proportion of hydroxypropyl cellulose (HPC) and carbomer as an adhesive, bleomycin can be directly compressed into a tablet or made into a duckbill suppository, which can be adhered to the cervix, and the formulation can be seen after 24 hours. Therefore, it is speculated that the dosage form can achieve satisfactory results in the treatment of uterine cancer.
3) Oral bioadhesive
After the drug is absorbed through the oral mucosa, it can directly enter the systemic circulation to avoid the first-pass effect. The apparent release rate constant of felodipine oral mucoadhesive tablets prepared with hypromellose (HPMC) K4M and carbomer 974P as bioadhesive polymers was 3.3% h-1, and the average adhesive force was 131.08-181.35g. It has been verified by in vivo experiments that the preparation has suitable adhesion to the oral cavity and is less irritating to the oral mucosa. In order to obtain a good effect on the treatment of periodontitis, metronidazole oral adhesive tablets were prepared with carbomer 940 and hydroxyethyl cellulose (HEC). It can be slowly released in the oral cavity, and the drug concentration detected in 12h is higher than the minimum inhibitory concentration.
4) Nasal bioadhesives
Nasal administration can be used for special patients where oral and intravenous administration is inconvenient or difficult to implement. Using Carbomer 971P as an excipient, apomorphine nasal powder was developed. The research on its sustained release shows that the bioavailability of this dosage form is equivalent to that of subcutaneous injection, and it has a sustained release effect. Najafabadi et al  reported that insulin was made into a carbomer gel spray.