When designing drug dosage forms, the basic differences between capsule vs caplet emerge for the first time in production process and cost. Capsules are filled typically by a rotary filling machine (e.g., Bosch GKF 2500) at the capacity of 3,000 capsules per minute and are produced at a cost of approximately $0.015 per tablet, while caplet (oval tablet) is compressed by a tablet press (e.g., Fette 3090) at a capacity of 5,000 capsules per minute. The cost of a single tablet is $0.012 (International Pharmaceutical Technology 2023 statistics). However, the capsule filling machine replacement time is only 15 minutes (45 minutes for replacement of caplet mold), compatible with small-batch multi-variety production, and the rate of global capsule production line switching is 42% higher than caplet in 2022 (IMARC Group report).
Physical properties of capsule vs caplet directly affect drug release and patient compliance. The capsules of gelatin disintegrated in gastric juice within 15-30 minutes and Cmax (time of peak concentration) was 25% faster than caplet (FDA bioequivalence guidelines), i.e., the peak time of ibuprofen capsules was 1.2 hours but for caplet it was 1.6 hours (Clinical Pharmacological Investigations). Yet the tensile strength of the caplet (80-120N) was vastly higher than that of the capsule shell (15-30N), its transport breakage rate merely 0.3% (1.8% for the capsule), and when Pfizer replaced a painkiller from a capsule to a caplet in 2021, logistics loss cost fell by 62% (annual company report).
Structure and stability comparison once again divides the market. The capsule shell was gelatin (13-15% moisture) or HPMC (5-8% moisture), and the rate of gelatin capsule adhesive increased to 5.7% under conditions of > 60%RH, while the deviation in caplet dissolution was ≤±5% even at 75%RH (USP<701> standard) due to the incorporation of sodium carboxymethyl starch (2-5%). Novartis substituted HPMC capsules with antifungal drug in 2023, and tropical country complaint level came down to 2% from 12%, but cost per tablet increased by $0.005 (investor conference call data). caplet received a thin coating (thickness of 0.05mm) to achieve enteric dissolution effect, which resulted in saving 30% material cost over capsule Eudragit coating (Journal of Drug Controlled Release study).
Regulations and market demand affect usage situations. 68% of US OTC painkiller markets use caplet (easily breakable dose), while capsules are used by 55% of Japan’s dysphagia patients (PMDA Annual Report). European Union requires heavy metal residue of the shell of the capsule to be ≤5ppm lead (EDQM standard), and caplet should control the excipient microbiological index (≤1000 CFU/g) since it comes into direct contact with API. In 2022, Indian pharma companies were banned from importing the capsule shell on the basis of containing an excessive amount of chromium (test value 8ppm), which cost $12 million in order value, and caplet export volume increased by 23% during the same period (Indian Ministry of Commerce and Industry statistics).
Technological change is pushing at existing boundaries. 3D-printed capsules (e.g., Aprecia ZipDose) can hold 1000mg of high-dose drug with > 90% porosity, while laser-drilled caplets (e.g., GSK’s Relenza) have lung targeted release with 40% boost in bioavailability. 2023 Moderna creates caplet, an mRNA vaccine that remains stable at room temperature for 18 months (6 months in liquid form) but one that costs 170% more to make than conventional capsules (BioNTech Collaboration Announcement). Smart capsules (with sensors) will have 25% of the premium market by 2028, and nanocrystalline caplet development in the insoluble drug market will reach 19.3%, much more than industry levels.