Capsule and caplet dissolution rate is very different, which is greatly affected by dosage form design and material. The gastric fluid (pH 1.2) disintegration time of the typical gelatin capsules (e.g. Capsule 0) is 3-5 minutes on average (USP specification), while the dissolution lag time of thin-film coated capsule tablets (e.g. Tylenol Quick acting tablets) is 8-12 minutes since one must first disintegrate the outer coating layer (hydroxypropyl methylcellulose coating, 50-80 μm thickness). An International Journal of Pharmacy study in 2023 showed that under small intestine simulated conditions (pH 6.8), capsule vs caplet had complete dissolution times of 15±2 minutes and 25±5 minutes, respectively, and capsule bioavailability peak (Cmax) was 18% higher.
Formulations and processes also differentiate properties. The rapid-release capsules (e.g., ibuprofen soft capsules) can release 90% of the drug within 5 minutes by liquid filling (particle size ≤10 μm), while the compression tablets (e.g., aspirin enteric-coated tablets) rely on disintegrators (cross-linked sodium carboxymethyl cellulose, 5%) and disintegrating force (≥10 N). The range of fluctuation of dissolution rate (RSD) was expanded from ±5% to ±12% of the capsule. Pfizer 2022 data showed capsule tablets’ dissolution rate decreased by 7% after 6 months at high temperature and humidity (40°C/75% RH) storage, while the capsule reduced only by 2% because the rate of water uptake of the gelatin shells (0.5 g/100g) was slower compared to tablet excipients (1.2 g/100g).
Enteric design avoids dissolution rationale. Enteric capsules (e.g., omeprazole DR Capsules) are coated with PH-sensitive acrylic resin (120-150μm thickness), the dissolution rate in stomach acid is ≤5%, and the release rate is ≥90% within 30 minutes of reaching the intestine (pH≥5.5); Enteric-coated tablets (e.g., diclofenac sodium enteric-coated tablets) due to deviation in coating uniformity (±15 μm), gastric release in certain batches was more than the standard (≥8%), which resulted in a recall of 1.2 million tablets by Indian pharma companies in 2021. Whereas the closed structure of the capsule resulted in better enteric material coverage (≥99%) than that of tablets (≥95%) and 30% greater dissolution stability (FDA 2023 dissolution database).
Applications are selected based on cost and production efficiency. Capsule filling capacities (e.g., Bosch GKF 2500 model) reach up to 300,000 tablets/hour at a cost per tablet of $0.03, while the combined press-coating line for capsule tablets (e.g., GEA PACTOR) only reaches 150,000 tablets/hour and costs increase to $0.05 / tablet. However, tablets’ compressive strength (≥100 N) during transportation is 1 time as high as that of capsules (≥50 N), and breakage rate is reduced from 0.5% to 0.1%. According to Novartis 2023 facts, the market share ratio of capsule vs caplet is 55:45%, with chronic drugs (e.g., blood pressure drugs) preferring tablets (stability advantage), and rescue painkillers (e.g., tramadol) preferring capsules (quick action) by 90%.
New technology changes dissolution pattern. 3D printed capsules (e.g., Aprecia ZipDose) utilize high porosity (≥90%) and reduce the dissolution time to less than 1 minute, while nanocrystal tablets (e.g., Merck Emend) use apis with particle size ≤200 nm to gain threefold improvement in the dissolution rate. In 2022, Moderna developed mRNA liposome capsules, and the efficiency of targeted release in the intestine reached 95%, a breakthrough compared to traditional tablets (70%). Roland Berger predicts that the competition of capsule vs caplet dissolution performance will drive the market for new delivery systems to $7.4 billion by 2028, with a compound annual growth rate of 9.3%.