Collapse temperature is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Updated 2026-02-05. Numbers and descriptions here follow the published literature rather than marketing material.
Secondary drying removes bound water that remains after ice sublimation. Shelf temperature is raised gradually while pressure remains low, reducing water content to a target range. Over-drying can cause brittleness or electrostatic issues, while under-drying affects stability. The endpoint is often judged by pressure rise tests, temperature measurements, or water content analysis. Scale-up depends on matching heat and mass transfer across equipment sizes. Small changes in shelf temperature or pressure can alter cycle length substantially.
Lyophilization, or freeze-drying, removes water from a material by freezing it and then lowering pressure so ice changes directly to vapor. The process relies on sublimation, the phase transition from solid to gas without an intervening liquid state. It is used for heat-sensitive materials that would degrade in conventional drying. The three stages are freezing, primary drying, and secondary drying, each with distinct temperature and pressure requirements. In practice, cycle design balances these variables.
Regulatory expectations for lyophilized products focus on consistent manufacture and documented stability. Batches are often monitored for moisture, appearance, potency, and sterility where applicable. Process parameters such as shelf temperature, chamber pressure, and drying time are recorded and controlled within validated ranges. Open questions remain about how best to predict long-term stability from short accelerated studies, especially for complex biologics. Variations in freezing rate and ice crystal size can produce differences that are not always visible but may affect performance.
After drying, a lyophilized product is usually sealed under vacuum or an inert gas to limit moisture uptake. Residual water content is measured because small changes can alter chemical stability and cake appearance. Storage temperature depends on the material; many biological products are kept at 2–8 °C, while some require −20 °C or colder. Exposure to ambient humidity during handling can cause the porous solid to absorb water and collapse. Container closures and stoppers are therefore selected for low moisture transmission and compatibility.
| Property | Value | Notes |
|---|---|---|
| Process name | Lyophilization or freeze-drying | Both terms appear in technical standards and literature. |
| Phase transition | Sublimation | Solid ice becomes vapor without a liquid step. |
| Typical chamber pressure | 0.05-0.5 mbar | Range depends on product temperature and equipment. |
| Typical product temperature | -40 °C to -10 °C | Measured during primary drying; formulation sets limits. |
| Water content after drying | 0.5-3% w/w | Target varies by material and stability needs. |
The process generally proceeds in three stages: freezing, primary drying, and secondary drying. During freezing, controlled cooling converts water into ice and may also crystallize or vitrify solutes. In primary drying, the pressure is lowered below the triple point, and heat is supplied so ice sublimes directly to vapor. Secondary drying removes water that remains bound to the solid matrix, yielding a low final water content. Product temperature must stay below the collapse or glass transition temperature to maintain structure. Cycle design therefore balances shelf temperature, chamber pressure, and time.
Freeze-drying is used for materials whose activity or structure depends on low temperature and low water content. Examples include certain biologics, diagnostic reagents, starter cultures, coffee, and porous inorganic precursors. The dried product forms a cake whose porosity aids rapid wetting and dissolution. Main drawbacks are high energy use, long cycle times, and sensitivity to formulation and equipment variation. Questions remain about how freezing rates and ice morphology affect batch uniformity, especially when moving from laboratory to production scale.
Lyophilization, also called freeze-drying, is a dehydration process in which a solvent, usually water, is frozen and then removed by sublimation under reduced pressure. The method preserves heat-sensitive materials that would degrade in conventional drying. Large-scale use grew during the mid-twentieth century for blood plasma and antibiotics, and it later expanded to vaccines, enzymes, foods, and advanced materials. The process produces a dry, porous solid that usually reconstitutes rapidly. It is distinct from simple evaporation because the solvent bypasses the liquid phase during primary removal.
Analytical methods for lyophilized solids must account for the low moisture content and the fragile cake. Karl Fischer titration is widely used for water content, while near-infrared spectroscopy can measure moisture non-destructively in sealed containers. X-ray diffraction and modulated differential scanning calorimetry help identify crystalline or amorphous phases. Residual solvent analysis may be needed if organic solvents were used during formulation. The combination of these methods supports batch release and long-term stability assessment.
Lyophilized products are typically stored as sealed solids in vials or syringes. Moisture ingress is a major concern because many dried cakes are hygroscopic and can lose stability when exposed to humid air. Storage temperature depends on the formulation; some products are kept refrigerated, while others are stable at room temperature. Container closure integrity and headspace moisture are often monitored. Light protection may also be required for some photosensitive materials.
The physics of lyophilization depends on phase boundaries and heat and mass transfer. During primary drying, heat supplied to the product must equal the latent heat of sublimation, while water vapor moves through the drying cake to the condenser. If shelf temperature or pressure is set too high, the ice front can exceed the collapse temperature, causing meltback or pore collapse. If conditions are too cold, drying slows and costs rise. Formulation excipients, vial geometry, and freezing rate alter these limits.
Equipment for lyophilization includes a vacuum chamber, temperature-controlled shelves, a condenser, and a vacuum pump. A refrigeration system cools the shelves and condenser below the product's freezing point. Process monitoring often uses Pirani and capacitance manometers, thermocouples, and resistance sensors. Cycle development balances product quality with time and energy use. Some products are annealed during freezing to improve crystallization of bulking agents. Open questions remain about scaling cycles between laboratory, pilot, and production freeze-dryers.
Residual moisture is a key quality attribute for lyophilized products. Water that remains after secondary drying can affect chemical stability, cake structure, and shelf life. Karl Fischer titration is a common method for measuring water content in the dried solid. The target range varies by product, but many biologics are dried to between 0.5% and 3% water by weight. Acceptable limits are set during development and confirmed by stability studies.
Stability studies examine how temperature, humidity, and time influence a lyophilized product. Accelerated conditions provide early information about degradation pathways, while long-term studies support shelf-life claims. The glass transition temperature of the dried formulation can indicate its physical stability, and storage above this temperature may increase molecular mobility and lead to collapse or aggregation. Container closure integrity also matters because moisture or oxygen ingress can degrade the product, so vial stoppers and seals are part of the quality system.
=== α2-Adrenergic receptor agonists === α2-Adrenergic receptor agonists like clonidine can improve sleep and may be useful in the treatment of insomnia. An example of this is in the treatment of insomnia in children and adolescents with attention deficit hyperactivity disorder (ADHD), for instance due stimulant therapy. Similarly to clonidine, the α2-adrenergic receptor agonist dexmedetomidine has sedative and hypnotic effects and is used to produce sedation in hospital settings. The sleep induced by dexmedetomidine is said to closely resemble natural sleep. The selective α2A-adrenergic receptor agonist tasipimidine (ODM-105) is under development for the treatment of insomnia and is in phase 2 clinical trials for this indication as of October 2024. α2-Adrenergic receptor agonists can produce hypotension and bradycardia as side effects, which has limited their use. Activation of the α2A-adrenergic receptor is thought to be responsible for most of the physiological effects of the α2-adrenergic receptors, including hypotension. On the other hand, the preferential α2A-adrenergic receptor agonist guanfacine appears to show less sedation and hypotension than clonidine. Tizanidine has been used off-label for sleep similarly to clonidine, but likewise shows less hypotensive potency in comparison.
=== Pharmacokinetics === Due to poor oral absorption, teicoplanin requires intravenous or intramuscular administration for systemic effect. Intramuscular administration achieves approximately 90% bioavailability. The drug exhibits high protein binding (90-95%) and is primarily eliminated through the kidneys unchanged, with minimal liver metabolism (2-3%) via hydroxylation. Clearance is reduced in patients with kidney impairment and is not significantly removed by hemodialysis. Teicoplanin exhibits a long half-life of 45-70 hours, allowing for once-daily dosing after loading doses. Although teicoplanin is primarily approved for intravenous and intramuscular use, several clinical and pharmacokinetic studies have explored its administration via the subcutaneous route. Subcutaneous teicoplanin has been reported as a feasible alternative in selected patients, particularly in outpatient, frail, or palliative care settings. Available evidence suggests that subcutaneous administration achieves pharmacokinetic and pharmacodynamic exposures comparable to intravenous dosing after appropriate loading, with good local tolerability. However, this route of administration remains off-label.
Vasoactive intestinal peptide (VIP; PHM27) Pituitary adenylate cyclase activating peptide (PACAP) Peptide PHI 27 (peptide histidine isoleucine 27) Growth hormone releasing hormone (GHRH) 1-24 Glucagon Secretin
=== Adverse effects === There have been several reports and small case series of acute liver injury with jaundice arising 1 to 3 months after starting herbal or dietary supplements containing S. baicalensis.
=== Pharmacodynamics === As a glucocorticoid, the lipophilic structure of prednisolone allows for easy passage through the cell membrane where it then binds to its respective glucocorticoid receptor (GCR) located in the cytoplasm. Upon binding, the formation of the GC/GCR complex causes dissociation of chaperone proteins from the glucocorticoid receptor enabling the GC/GCR complex to translocate inside the nucleus. This process occurs within 20 minutes of binding. Once inside the nucleus, the homodimer GC/GCR complex binds to specific DNA binding sites known as glucocorticoid response elements (GREs) resulting in gene expression or inhibition. Complex binding to positive GREs leads to the synthesis of anti-inflammatory proteins while binding to negative GREs blocks the transcription of inflammatory genes. They inhibit the release of signals that promote inflammation such as nuclear factor-Kappa B (NF-κB), Activator protein 1 (AP-1), nuclear factor of activated T-cells (NFAT), and stimulate anti-inflammatory signals such as the interleukin-10 gene. All of them will collectively cause a sequence of events, including the inhibition of prostaglandin synthesis and additional inflammatory mediators. Glucocorticoids also inhibit neutrophil cell death and demargination. As well as phospholipase A2, which in turn lessens arachidonic acid derivative genesis.
Sources: en.wikipedia.org
=== March === 1 March – Statistics released by the Scottish Government indicate Scotland's economy grew by 0.1% during the three months from October–December 2022. 2 March – Minister for Transport Jenny Gilruth announces plans to nationalise the overnight Caledonian Sleeper train service that links London with several locations in Scotland, taking effect from 25 June. 3 March The Educational Institute of Scotland and other teaching unions call off a planned 20 days of rolling strikes scheduled to begin on 13 March after receiving an improved pay offer from the Scottish Government, worth 14.6% over 28 months. The proposals will now be put to a ballot. Loganair announces it will suspend flights between Inverness Airport and some island airports for at least six weeks from 17 March because of industrial action scheduled to begin at Highland and Islands Airports Limited. 6 March – BBC News reports that the Scottish Prison Service is to be investigated for corporate manslaughter over the death of Allan Marshall, a prisoner at HMP Edinburgh, who died after being restrained by 13 prison officers in 2015. 7 March – STV hosts the first televised debate of the Scottish National Party leadership election. 10 March – Members of Scotland's largest teaching union, the Educational Institute of Scotland, vote to accept a pay deal from the Scottish Government that will end ongoing strikes in schools. 13 March – Voting opens in the Scottish National Party leadership election.
=== Lobbying the FDA === In 2011, the FDA made it a priority to clarify the requirements for approval for such a closed-loop monitoring and drug delivery device for T1D, and announced it was preparing draft guidelines. Breakthrough T1D launched a campaign to influence those guidelines to be lenient. After the first closed-loop device was approved in 2016, Breakthrough T1D lobbied insurance companies to cover it. The campaign also put resources into educating people with diabetes on how to navigate health insurance in the United States, and into lobbying Congress to continue funding diabetes research through the NIH. The FDA lobbying campaign was part of a gradual realignment of the organization to focus on issues other than helping find a cure for type 1 diabetes, but to help treat and manage the disease. This broadened scope meant that the organization increasingly directed its funds to education and advocacy, along with research funding. This included lobbying insurance companies to pay for CGM devices, educating patients on how to advocate for themselves, and lobbying Congress for more NIH funding.
This requires duties of disclosure in how a retirement fund is run, funding and insurance to guard against insolvency, but not yet that voting rights are only cast on the instructions of investors. By contrast, the Undertakings for Collective Investment in Transferable Securities Directive 2009 does suggest that investors in a mutual fund or ("collective investment scheme") should control the voting rights. The UCITS Directive 2009 is primarily concerned with creating a "passport". If a firm complies with rules on authorisation, and governance of the management and investment companies in an overall fund structure, it can sell its shares in a collective investment scheme across the EU. This forms a broader package of Directives on securities and financial market regulation, much of which has been shaped by experience in the 2008 financial crisis. Additional rules on remuneration practices, separating depositary bodies in firms from management and investment companies, and more penalties for violations were inserted in 2014. These measures are meant to decrease the risk to investors that an investment goes insolvent. The Markets in Financial Instruments Directive 2004 applies to other businesses selling financial instruments. It requires similar authorisation procedures to have a "passport" to sell in any EU country, and transparency of financial contracts through duties to disclose material information about products being sold, including disclosure of potential conflicts of interest with clients.
== Techniques == Traditional gum grafting will have a piece of the gums harvested from the roof of the mouth and sutured facing the exposed root to increase the lost keratinized tissue. The limited amount of donor tissue available from the palate and morbidity are the limiting factors of this technique. Allografting can be used to supply the surgeon with larger amount of tissues when needed, but complications in healing and the risk of possible disease transmission should be considered and disclosed to the patient when opting for such technique.
Sources: en.wikipedia.org
== Counteraction == A 2015 study, reported in the journal Ergonomics, showed that, for twenty healthy subjects, exposure to blue-enriched light during the post-lunch dip period significantly reduced the EEG alpha activity, and increased task performance.
===== MeSH D08.811.682.690 – oxygenases ===== MeSH D08.811.682.690.416 – dioxygenases MeSH D08.811.682.690.416.277 – catechol 1,2-dioxygenase MeSH D08.811.682.690.416.305 – catechol 2,3-dioxygenase MeSH D08.811.682.690.416.319 – cysteine dioxygenase MeSH D08.811.682.690.416.326 – homogentisate 1,2-dioxygenase MeSH D08.811.682.690.416.328 – 3-hydroxyanthranilate 3,4-dioxygenase MeSH D08.811.682.690.416.330 – 4-hydroxyphenylpyruvate dioxygenase MeSH D08.811.682.690.416.333 – indoleamine-pyrrole 2,3-dioxygenase MeSH D08.811.682.690.416.444 – lipoxygenase MeSH D08.811.682.690.416.444.050 – arachidonate lipoxygenases MeSH D08.811.682.690.416.444.050.055 – arachidonate 5-lipoxygenase MeSH D08.811.682.690.416.444.050.060 – arachidonate 12-lipoxygenase MeSH D08.811.682.690.416.444.050.065 – arachidonate 15-lipoxygenase MeSH D08.811.682.690.416.444.525 – protocatechuate 3,4-dioxygenase MeSH D08.811.682.690.416.722 – tryptophan oxygenase MeSH D08.811.682.690.562 – inositol oxygenase MeSH D08.811.682.690.708 – mixed function oxygenases MeSH D08.811.682.690.708.062 – benzoate 4-monooxygenase MeSH D08.811.682.690.708.125 – catechol oxidase MeSH D08.811.682.690.708.125.500 – monophenol monooxygenase MeSH D08.811.682.690.708.170 – cytochrome p-450 enzyme system MeSH D08.811.682.690.708.170.040 – aryl hydrocarbon hydroxylases MeSH D08.811.682.690.708.170.040.024 – 7-alkoxycoumarin o-dealkylase MeSH D08.811.682.690.708.170.040.050 – aniline hydroxylase MeSH D08.811.682.690.708.170.040.110 – benzopyrene hydroxylase MeSH D08.811.682.690.708.170.040.332 – cytochrome p-450 cyp1a1 MeSH D08.811.682.690.708.170.040.443 – cytochrome p-450 cyp1a2 MeSH D08.811.682.690.708.170.040.499 – cytochrome p-450 cyp2b1 MeSH D08.811.682.690.708.170.040.555 – cytochrome p-450 cyp2d6 MeSH D08.811.682.690.708.170.040.777 – cytochrome p-450 cyp2e1 MeSH D08.811.682.690.708.170.040.888 – cytochrome p-450 cyp3a MeSH D08.811.682.690.708.170.085 – camphor 5-monooxygenase MeSH D08.811.682.690.708.170.500 – alkane 1-monooxygenase MeSH D08.811.682.690.708.170.915 – steroid hydroxylases MeSH D08.811.682.690.708.170.915.050 – aldosterone synthase MeSH D08.811.682.690.708.170.915.099 – aromatase MeSH D08.811.682.690.708.170.915.200 – cholesterol 7 alpha-hydroxylase MeSH D08.811.682.690.708.170.915.212 – cholesterol side-chain cleavage enzyme MeSH D08.811.682.690.708.170.915.400 – 25-hydroxyvitamin d3 1-alpha-hydroxylase MeSH D08.811.682.690.708.170.915.720 – steroid 11-beta-hydroxylase MeSH D08.811.682.690.708.170.915.730 – steroid 12-alpha-hydroxylase MeSH D08.811.682.690.708.170.915.737 – steroid 16-alpha-hydroxylase MeSH D08.811.682.690.708.170.915.748 – steroid 17-alpha-hydroxylase MeSH D08.811.682.690.708.170.915.760 – steroid 21-hydroxylase MeSH D08.811.682.690.708.292 – dopamine beta-hydroxylase MeSH D08.811.682.690.708.392 – fatty acid desaturases MeSH D08.811.682.690.708.392.312 – beta-carotene 15,15'-monooxygenase MeSH D08.811.682.690.708.392.468 – Linoleoyl-CoA desaturase MeSH D08.811.682.690.708.392.625 – stearoyl-coa desaturase MeSH D08.811.682.690.708.401 – gamma-butyrobetaine dioxygenase MeSH D08.811.682.690.708.410 – heme oxygenase (decyclizing) MeSH D08.811.682.690.708.410.500 – heme oxygenase-1 MeSH D08.811.682.690.708.425 – 4-hydroxybenzoate 3-monooxygenase MeSH D08.811.682.690.708.557 – kynurenine 3-monooxygenase MeSH D08.811.682.690.708.601 – phenylalanine hydroxylase MeSH D08.811.682.690.708.660 – procollagen-lysine, 2-oxoglutarate 5-dioxygenase MeSH D08.811.682.690.708.673 – procollagen-proline dioxygenase MeSH D08.811.682.690.708.715 – prostaglandin-endoperoxide synthases MeSH D08.811.682.690.708.749 – squalene monooxygenase MeSH D08.811.682.690.708.783 – steroid hydroxylases MeSH D08.811.682.690.708.783.050 – aldosterone synthase MeSH D08.811.682.690.708.783.099 – aromatase MeSH D08.811.682.690.708.783.200 – cholesterol 7 alpha-hydroxylase MeSH D08.811.682.690.708.783.212 – cholesterol side-chain cleavage enzyme MeSH D08.811.682.690.708.783.400 – 25-hydroxyvitamin d3 1-alpha-hydroxylase MeSH D08.811.682.690.708.783.720 – steroid 11-beta-hydroxylase MeSH D08.811.682.690.708.783.730 – steroid 12-alpha-hydroxylase MeSH D08.811.682.690.708.783.737 – steroid 16-alpha-hydroxylase MeSH D08.811.682.690.708.783.745 – steroid 17-alpha-hydroxylase MeSH D08.811.682.690.708.783.760 – steroid 21-hydroxylase MeSH D08.811.682.690.708.826 – trans-cinnamate 4-monooxygenase MeSH D08.811.682.690.708.870 – tryptophan hydroxylase MeSH D08.811.682.690.708.923 – tyrosine 3-monooxygenase
=== Pharmacokinetics === Bimatoprost is well absorbed through the cornea. It starts lowering intraocular pressure after four hours, lasting for at least 24 hours. A low percentage enters the bloodstream. In the blood plasma, peak concentrations are reached after 10 minutes, then drop below the detection limit of 25 pg/ml after 1.5 hours. The substance does not accumulate in the body. Plasma protein binding is 88%. Bimatoprost is metabolized by oxidation, N-deethylation and glucuronidation, forming a variety of metabolites. Biological half-life was measured to be 45 minutes after intravenous infusion. 67% are eliminated via the kidney, and 25% via the feces.
== History == Sarepta started in Corvallis, Oregon on January 1, 1980 and was originally named Antivirals Inc. After occupying several research laboratory spaces in Corvallis, the company opened a production laboratory in Corvallis in February 2002 and was renamed AVI BioPharma Inc. The company made headlines in 2003 when it announced work on treatments for severe acute respiratory syndrome (SARS) and the West Nile virus. In July 2009, the company announced they would move their headquarters from Portland, Oregon, north to Bothell, Washington, near Seattle. At that time, the company led by president and CEO Leslie Hudson had 83 employees and quarterly revenues of $3.2 million. AVI had yet to turn a profit and had not yet developed any commercial products as of July 2009. The company lost $19.7 million in the second quarter of 2009, and then won an $11.5 million contract with the U.S. Department of Defense's Defense Threat Reduction Agency in October 2009. By this time, the company had completed its headquarters move to Bothell. In 2012, the company moved a second time, to Cambridge, Massachusetts. At the time, CEO Chris Garabedian indicated the move was motivated by the need to recruit expertise in rare diseases. The Corvallis laboratory facility was closed in 2016. In June 2017, Sarepta Therapeutics appointed former Allergan executive Doug Ingram as its new CEO to replace Edward Kaye who had announced plans to step down earlier that year.
== Aviation == Aéroports de Montréal, Quebec, Canada Aéroports du Mali, airport operator in Mali Agency debit memo in the travel industry Ardmore Municipal Airport in Oklahoma, US (IATA airport code ADM) Pilot decision making, also known as aeronautical decision-making Air data module
Sources: en.wikipedia.org
Conventional drying uses heat to evaporate liquid water, often at temperatures that can degrade sensitive materials. Lyophilization freezes the material first and then removes water by sublimation under vacuum. This avoids prolonged exposure to liquid water and high heat.
Lowering pressure reduces the boiling point of water and allows ice to sublimate at temperatures below freezing. Vacuum also limits convective heat transfer, so heat is usually supplied by shelves or radiation. The pressure must stay below the vapor pressure of ice at the product temperature.
The cycle typically includes freezing, primary drying, and secondary drying. Freezing solidifies water and sets the pore structure; primary drying removes bulk ice; secondary drying removes bound water. Some cycles add annealing or pre-freezing steps.
Most are held in sealed containers at controlled temperatures, often 2–8 °C, while some require frozen storage. Protection from moisture and light helps preserve the dry matrix. Exact conditions are set by the manufacturer or study protocol.