The oral administration of drugs is the most appealing route of administration because of its many advantages. Solid oral tablets are among the most favored options because they are simple to manufacture, easy to consume, offer exact dosing, and are more stable than oral liquids. 1 Capsules are the first dosage form to be selected for orally administered drugs, even though they can be administered through the rectum or vagina. Capsules have been extensively utilized in clinical trials and drug development. From the patient’s point of view, capsules provide an odorless and tasteless delivery system, as they do not require a secondary coating process. Capsules are more easily swallowed by several patients than tablets. Active pharmaceutical ingredients (APIs) and excipients required to formulate the API are generally contained in a small hard or soft gelatin shell in the capsule. Following drug delivery, gelatin dissolves in body fluids in the intestine, and the therapeutic compounds within the capsule are released. 2 A soft gel capsule (SGC) is a single, closed soft gelatin vessel that contains a liquid, suspension, or semi-solid material, referred to as the fill. Soft gelatin shells are usually made of film-forming substances such as gelatin and water-soluble or water-dispersible plasticizers, which provide flexibility. Coloring agents, flavorings, sweeteners, drugs, and preservatives are some of the optional additives. Soft gel capsules can also be coated to protect against stomach acids for certain purposes. Soft gelatin capsules are frequently used in the dietary supplement market for the delivery of liquids, suspensions, pastes, and powders. 3 Soft gelatin capsules, a dose form of close to a hundred years, have acquired tremendous importance as a vehicle for medication since the 1930s. This is because numerous unstable drugs, which are susceptible to oxidation, light, heat, or humidity, can be safely encapsulated without losing their effectiveness. The production of soft gelatin capsules requires skilled and experienced human resources, proper management, and a well-planned and designed facility in which GMP and environmental conditions for manufacturing are fulfilled. 4

SGC offers the advantage of delivering therapeutic agents that require very low doses with exactness, for example, cardiac glycosides and vitamin D analogs. They are available in a wide variety of sizes, shapes (including spherical, elliptical, and oblong shapes as well as custom tube shapes with and without twist-off), and colors, leading to many attractive finished products for consumers. For oral use in humans, SGC must not be larger than 20 mm oblong, 16 mm oval, and 9 mm round. 5 SGCs were manufactured under conditions controlled by a precise temperature and humidity. The process consisted of the following steps: gelatin paste preparation, preparation of the fill material (API or nutrients), encapsulation, drying and examination of the capsules, and storage and packaging. 6, 7, 8 In the US, multivitamins/mineral supplements fall under dietary supplements with a minimum of three vitamins and minerals but no herbs, hormones, or drugs, and follow the Food and Drug Administration standards for safe doses to avoid unhealthy results. Multivitamins usually consist of lipid-soluble vitamins such as vitamins A, D, E, and K., and water-soluble vitamins such as thiamine (vitamin B1), riboflavin (vitamin B2), vitamin B6, vitamin B12, vitamin C, folic acid, niacin, pantothenic acid, and inositol. They also include minerals, such as calcium, Phosphorus, Iron, Iodine, magnesium, manganese, copper, and zinc.

Gelatin capsules are also widely employed as carriers of specific vitamins, minerals, and pharmaceuticals. Gelatin is widely utilized in the food industry, especially in vitamin and mineral capsules, due to its digestibility and compatibility with many vitamins, minerals, and APIs. 9 The Recommended Dietary Allowance (RDA) or Adequate Intake (AI) is the norm of a balanced diet, establishing the minimum quantities of necessary vitamins and nutrients to meet the population's health needs. 10, 11 Some of the multivitamin soft gelatin capsules available in the market are Revital capsules (Vitamin B1, B2, B6, B5, C, E and minerals like Ca+, Fe, Mg, Mn, Zn, Cu and Ginseng), Moringa capsules (Vitamin- B1, B2, B6, B3, B7, Vitamin -C, A, D, E, K.), Nergipot capsules (Vitamin and mineral supplement), Riva-L capsule (Lysine, B1, B2, B6 and B12, and simavite capsule (Vital minerals and vitamins). The main objective of this study was to develop a soft gelatin capsule dosage form of a suspension of multivitamins and minerals. The formulation seeks to fulfil the nutritional levels required for dietary supplements to correct vitamin deficiency.

Before formulation, pre-formulation studies on Active Pharmaceutical Ingredients (APIs) were carried out. Different formulation parameters were tested to determine product stability and efficacy. Five different fill medicament compositions (F1, F2, F3, F4, and F5) were developed during the formulation development phase of the multivitamin soft gelatin capsules. Formulations F1, F2, F3, and F4, with multivitamins, minerals, and hydrogenated vegetable oil, failed to form a stable suspension because the level of soya lecithin was too low, resulting in weak viscosity and consistency. Composition F5, with multivitamins, minerals, soybean oil, and soya lecithin, was spontaneously dispersible and had satisfactory consistency and viscosity, rendering it the best suspension fill.

The composition of gelatin shell was made from the gel pastes, which were subsequently employed in encapsulation (Table 1). In testing the soft gelatin capsules, the gelatin solution's viscosity was within the acceptable range of 20-40 mps, reflecting proper flow and lack of flow during encapsulation. The bloom strength of gelatin was also tested and was found to be within the normal range of 150-250. The drying loss of the capsule shell, which is usually 6% to 13% water, was also within the acceptable range.

For the optimized formulation, soft gelatin capsules were tested for general appearance, weight, and other physical attributes. The capsules were found to be oblong, black, and pleasing in appearance (Figure 1). The capsule weight variation averaged from 12.40% to 13.10% in F5, which is within the acceptable limit of ±2.0%. The uniformity of the fill weight was between -0.57% and +1.12%, which was again within the official limits of ±2%. The capsule hardness varied from 6.4N to 7.5N, which falls in the normal range of 5-8 Newtons. The disintegration time of the capsules was found to be below 12 min, which is optimum because official limits are not provided for soft gelatin capsules. In addition, the related substances present in F5 were within an acceptable impurity level of 0.50%.

Accelerated stability testing of F5 was conducted for two months at 40 ± 2°C and 75% RH ± 5%. The test results showed the satisfactory stability of the in-house product. The F5 assay was 110% at 1 month and 106.92% at 2 months, both within acceptable limits. The levels of related substances in F5 were within the range of 0.50% at both 1-month and 2-month stability tests.

The primary aim of the present study was to formulate a generic multivitamin supplement in suspension to fulfil the requirements of consumers who suffer from nutritional deficiencies or have diverse nutritional needs. The present market has widely accepted multivitamin and mineral supplements because of its convenience, high stability, and absorption values. Stephen et al. 15 carried out a study on Diclofenac potassium liquid-filled soft gelatin capsules (DPSGC), with the objective of assessing the efficacy and safety of DPSGC 25 mg in a large-scale, double-blind, placebo-controlled trial in patients with pain. The results indicated that DPSGC effectively relieved pain in patients, suggesting that this new formulation of diclofenac potassium may be an effective treatment for mild to moderate acute pain. Gennadios et al. 16 filed a patent for a soft gelatin composition in the form of 30-60% weight film-forming material, 5-35% weight water-dispersible material, and 25-65% weight purified water. The film-forming material consisted of gelatin and gum acacia. Gelatin-extended capsules had physical properties similar to those of control capsules but revealed greater elasticity when the gelatin-gum acacia mixture was formed and showed superior stability.

The major challenge encountered in the formulation of SGCs of multivitamins and minerals is the development of consistently stable suspension fills. This was mainly because the formulation contained both fat- and water-soluble vitamins and minerals. The pre-formulation investigation of the active ingredients was within the IH limits. The physicochemical parameters of the soft gelatin capsules were in accordance with the official standards. The capsules were satisfactory with no color change, blooming, or leakage. The in vitro test parameters of the capsules complied with official standards. The results of multivitamin and mineral assays were within the normal range. The F5 formulation had good stability after two months at 40°C and 75% RH. Soft gelatin capsules provided protection against degradation, and this is an effective formulation method. The advantages of soft gelatin capsules extend beyond multivitamins, as seen in studies on other formulations such as diclofenac potassium SGCs, which also demonstrated effective delivery and stability. 17, 3 However, challenges remain in optimizing shelf-life and stability of various formulations, necessitating ongoing research in this area. 3

In summary, this study successfully developed a soft gelatin capsule dosage form of multivitamins in suspension form as an effective dietary supplement to address nutritional imbalance and vitamin deficiencies. The pre-formulation studies and physicochemical parameters of the capsules were within acceptable limits without any defects such as color change, blooming, or leakage. The capsules showed satisfactory stability under accelerated conditions, and the optimized formulation exhibited content uniformity and protection against degradation. This process is an effective method for formulating multivitamin soft gelatin capsules, and further research on bioavailability and clinical trials are suggested to evaluate their therapeutic potential.