primary drying comes up often in conversation and rarely with the context attached. Here we lay out the basics in order, then work through the practical considerations.
Last reviewed on 2026-05-02. Where a claim depends on a specific study, the study is described rather than over-claimed.
After primary drying, secondary drying removes water that remains bound to the material. This stage raises the shelf temperature while maintaining low pressure, which encourages desorption of unfrozen water. Residual moisture can be reduced to a low percentage, improving stability for many products. The process parameters, including freezing rate, shelf temperature, and chamber pressure, influence the final pore structure and reconstitution behavior. Control of these variables helps prevent collapse or meltback during drying.
A formulation often contains excipients that protect the active ingredient during freezing and drying. Bulking agents provide structure, while lyoprotectants stabilize sensitive molecules. The freezing step can produce ice crystals whose size and distribution affect the drying rate, and cycle design includes freezing, annealing, and drying phases. If the product temperature rises above a critical value, the cake may collapse or lose its porous structure. Successful lyophilization therefore depends on the interaction between formulation, equipment, and cycle design.
After lyophilization, the product is usually a porous cake or powder with a large internal surface area. This structure can absorb moisture quickly if exposed to humid air, so vials are sealed under vacuum or an inert gas. Moisture uptake may lower the glass transition temperature of the dried matrix and accelerate chemical or physical degradation. Storage conditions therefore depend on the formulation, container, and intended shelf life. Some products remain stable at room temperature, while others require refrigeration or freezing.
Quality control for lyophilized products includes appearance, cake structure, reconstitution time, pH, residual moisture, and potency. Residual moisture is a key attribute because excess water can reduce stability, while excessively low moisture may cause structural changes or aggregation in some systems. Stability studies compare real-time and accelerated conditions to estimate shelf life. Analytical methods must be validated for the specific matrix, container, and moisture range. Sterility and container integrity are also monitored for sterile products.
Handling practices aim to prevent moisture ingress and mechanical damage. Vials should remain stoppered and crimped until use, and reconstitution should follow the labeled diluent and volume. Shipping may involve temperature-controlled containers and desiccants, but direct contact between desiccant and product is avoided. Regulatory guidance expects documented storage conditions, excursion assessments, and stability commitments. Open questions remain about how best to predict long-term stability from short accelerated studies for every formulation class.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Freeze-drying, lyophilisation | Lyophilization is the American spelling; lyophilisation is British |
| Primary drying mechanism | Sublimation of ice | Occurs under vacuum below the triple point |
| Typical chamber pressure | 0.05-0.5 mbar | Range depends on product and equipment |
| Typical shelf temperature during freezing | -40 to -20 °C | Lower temperatures may be used for labile products |
| Resulting product form | Porous cake or powder | Appearance depends on formulation and cycle |
Lyophilization removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts liquid water into ice and concentrates dissolved solids. Primary drying then lowers chamber pressure so ice changes directly into vapor without passing through a liquid phase. Secondary drying raises the shelf temperature to remove bound water that remains after ice sublimation. The result is a dry, porous structure that can be reconstituted later.
Formulation composition influences whether freeze-drying produces an intact cake or a collapsed mass. Excipients such as sugars and polymers can raise the collapse temperature and provide bulk during drying. The critical temperature for primary drying is often the collapse temperature or the glass transition temperature of the maximally concentrated phase. If the product temperature exceeds this threshold, the frozen matrix may soften and lose structure. Established practice therefore links shelf temperature and chamber pressure to the formulation's thermal properties.
The physics of freeze-drying couples heat transfer, mass transfer, and phase change. Heat supplied through the shelf must reach the sublimation front without melting the ice or degrading the product. Water vapor then travels through the already dried layer and leaves the chamber, where low pressure and cold traps keep it from returning. The dried layer acts as a resistance to vapor flow, so drying rate changes as the front recedes. Open questions remain about how pore structure and formulation heterogeneity affect drying uniformity at larger scales.
After lyophilization, the dried product is often sealed under vacuum or an inert gas to limit moisture and oxygen exposure. Vials, stoppers, and seals must maintain their barrier throughout shelf life. Storage temperature depends on product sensitivity: some cakes tolerate controlled room temperature, while labile biologics require refrigeration. Humidity is a critical variable because dried cakes are hygroscopic and can absorb water when exposed to air. Handling procedures therefore limit open-vial time and use desiccated environments for sampling.
Quality control for lyophilized materials examines appearance, reconstitution time, residual moisture, and mechanical integrity. An acceptable cake is usually uniform and porous, though appearance alone does not prove stability. Karl Fischer titration is a common method for water content, while differential scanning calorimetry can reveal glass transition events. Stability studies track potency, aggregation, and moisture over time under defined temperature and humidity conditions. Specifications are product-specific and may include sterility and endotoxin tests for sterile preparations.
==== Colombia ==== According to a 2010 USDA Foreign Agricultural Service report, each small town in Colombia typically has a fresh food market that is supplied by local production and opens at least once a week. The report described both retail and wholesale markets that provide food products for "Mom'n Pop stores". It estimated the number of such markets at around 2,000, but noted that the number was slowly decreasing in large cities despite the presence of large markets like Corabastos in Bogotá.
=== Taste disturbances === Some raw pine nuts can cause pine mouth syndrome, a taste disturbance lasting from a few days to a few weeks after consumption. A bitter, metallic, unpleasant taste is reported. There are no known lasting effects, with the United States Food and Drug Administration reporting that there are "no apparent adverse clinical side effects". Raw nuts from Pinus armandii, mainly in China, may be the cause of the problem. Metallic taste disturbance is typically reported 1–3 days after ingestion, being worse on day two and typically lasting up to two weeks. Cases are self-limited and resolve without treatment.
== NAD+ precursors == The members of the NAD+ precursor family include tryptophan (Trp), nicotinic acid (NA), nicotinamide (NAM), nicotinamide ribose (NR), nicotinamide mononucleotide (NMN), reduced nicotinamide ribose (NRH) and reduced nicotinamide mononucleotide (NMNH) of these, the majority are logically vitamin B substances or their congeners Based on the bioavailability of its precursors, there are three pathways for the synthesis of NAD+ in cells.
Sources: en.wikipedia.org
Skin grafts have been shown to control the recurrence of the disease. Extracorporeal shock wave therapy (ESWT) has, in some cases, been reported to significantly reduce pain and improve walking ability in patients with plantar fibromatosis. Collagenase injection, FDA-approved for Dupuytren's contracture with favorable outcomes, showed no benefit in a reported case of plantar fibromatosis. Cryotherapy has also been reported as an effective treatment for Ledderhose disease, with an approximate 80% success rate and potentially lower recurrence than conventional surgery. Cortisone injections, such as triamcinolone, and clobetasol ointments have been shown to stall the progression of the disease temporarily, although the results are subjective and large-scale studies far from complete. Injections of superoxide dismutase have proven to be unsuccessful in curing the disease while radiotherapy has been used successfully on early-stage Ledderhose nodules. Topical verapamil is also used to treat plantar fibromatosis.
ACC synthase reaches optimal activity in conditions of pH 8.5 and with Km = 20 um relative to its substrate, SAM. ACC Synthase and ethylene biosynthesis are regulated by a whole host of stimuli. Stresses such as wounding, noxious chemicals, auxin, flooding, and indole-3-acetic acid (IAA) promote ethylene synthesis, creating a positive feedback cycle with ACC synthase, up-regulating its activity. However, it is also inhibited by a number of compounds as well. S-Adenosylethionine can bind as a substrate for ACC synthase (with higher affinity than SAM) and therefore inhibit any reaction with SAM. ACC Synthase is also competitively inhibited by aminoethoxyvinylglycine (AVG) and aminooxyacetic acid (AOA), inhibitors to many pyridoxal phosphate-mediated enzymic reactions. They are natural toxins that cause slow binding inhibition by interfering with the coenzyme pyridoxal phosphate. ACC synthase activity is also inhibited by intermediates of the activated methyl cycle and the methionine-recycling pathway: 5′-methylthioadenosine, α-keto-γ-methylthiobutyric acid, and S-adenosylhomocysteine.
In the early years of using the technique, it was understood that it depended on the atmospheric 14C/12C ratio having remained the same over the preceding few thousand years. To verify the accuracy of the method, several artefacts that were datable by other techniques were tested; the results of the testing were in reasonable agreement with the true ages of the objects. Over time, however, discrepancies began to appear between the known chronology for the oldest Egyptian dynasties and the radiocarbon dates of Egyptian artefacts. Neither the pre-existing Egyptian chronology nor the new radiocarbon dating method could be assumed to be accurate, but a third possibility was that the 14C/12C ratio had changed over time. The question was resolved by the study of tree rings: comparison of overlapping series of tree rings allowed the construction of a continuous sequence of tree-ring data that spanned 8,000 years. (Since that time the tree-ring data series has been extended to 13,900 years.) In the 1960s, Hans Suess was able to use the tree-ring sequence to show that the dates derived from radiocarbon were consistent with the dates assigned by Egyptologists. This was possible because although annual plants, such as corn, have a 14C/12C ratio that reflects the atmospheric ratio at the time they were growing, trees only add material to their outermost tree ring in any given year, while the inner tree rings don't get their 14C replenished and instead start losing 14C through decay. Hence each ring preserves a record of the atmospheric 14C/12C ratio of the year it grew in.
Sources: en.wikipedia.org
No.5 Squadron South African Air Force operated Mustang Mk IIIs (P-51B/C) and Mk IVs (P-51D/K) in Italy during World War II, beginning in September 1944, when the squadron converted to the Mustang Mk III from Kittyhawks. The Mk IV and Mk IVA came into SA service in March 1945. These aircraft were generally camouflaged in the British style, having been drawn from RAF stocks; all carried RAF serial numbers and were struck off charge and scrapped in October 1945. In 1950, 2 Squadron SAAF was supplied with F-51D Mustangs by the United States for Korean War service. The type performed well in South African hands before being replaced by the F-86 Sabre in 1952 and 1953. South Korea
Antibody mimetics are organic compounds that, like antibodies, can specifically bind antigens, but that are not structurally related to antibodies. They are usually artificial peptides or proteins with a molar mass of about 3 to 20 kDa. (Antibodies are ~150 kDa.) Nucleic acids and small molecules are sometimes considered antibody mimetics as well, but not artificial antibodies, antibody fragments and fusion proteins composed from these. Common advantages over antibodies are better solubility, tissue penetration, stability towards heat and enzymes, and comparatively low production costs. Antibody mimetics are being developed as therapeutic and diagnostic agents.
=== Integration of Biocon Biologics === On 6 December 2025, Biocon announced that it would fully integrate its biosimilars subsidiary Biocon Biologics Limited (BBL) as a wholly owned subsidiary, in a corporate action that valued BBL at US$5.5 billion and marked a pivot away from a previously planned initial public offering (IPO) of the biosimilars business. The company said the integration would simplify the group's corporate structure, remove the holding-company discount that had weighed on its valuation, and combine its generics and biosimilars operations into a single listed entity focused on diabetes, oncology and immunology. Under the plan, Biocon acquired the minority stakes held by Serum Institute Life Sciences, Tata Capital Growth Fund II and Activ Pine LLP through a share swap of 70.28 Biocon shares for every 100 BBL shares, priced at ₹405.78 per Biocon share. It also bought out the residual stake held by Mylan Inc. (Viatris) for US$815 million, comprising US$400 million in cash and US$415 million via a share swap, with the swap ratios based on independent valuations by EY. To fund the cash component payable to Viatris, Biocon raised approximately ₹4,150 crore (about US$460 million) through a qualified institutional placement (QIP) completed on 14 January 2026. The integration was completed by 31 March 2026, making Biocon Biologics a wholly owned subsidiary of Biocon Limited and creating a unified entity spanning biosimilars, insulins, generics and peptides. The leadership transition that followed is described under Corporate governance.
Sources: en.wikipedia.org
Lyophilization removes water by sublimation from a frozen material, while evaporation changes liquid water into vapor. The low-pressure freezing step avoids the liquid phase and can preserve heat-sensitive structures.
Vacuum lowers the pressure below the triple point of water, allowing ice to sublimate directly into vapor. It also helps remove water vapor from the product chamber and shortens primary drying.
Many aqueous solutions and suspensions can be freeze-dried, but some formulations collapse or do not form a stable cake. The process requires careful formulation and cycle development.
Collapse occurs when the product temperature rises above its collapse or eutectic temperature during drying. The frozen matrix loses structure, producing a shrunken or melted appearance. This can slow reconstitution and may affect stability.