Everything below concerns Lyophilization. We keep the language plain, cite what the science says, and separate well-supported claims from open questions.
Last reviewed on 2026-01-18. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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 process usually has three stages: freezing, primary drying, and secondary drying. Freezing sets the ice crystal structure and can determine pore size in the final cake. Primary drying removes free ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, although some water may remain as part of the solid. Cycle parameters depend on formulation, fill volume, vial type, and equipment performance.
The physical chemistry of freezing influences whether a formulation forms an amorphous glass or a crystalline solid. Amorphous systems can collapse if product temperature rises above the glass transition temperature of the freeze concentrate. Crystalline systems may show eutectic melting, where ice and solute melt together at a fixed temperature. Formulators add bulking agents, lyoprotectants, and buffers to preserve structure and biological activity. The optimum cycle keeps product temperature below critical thresholds during primary drying while allowing efficient sublimation.
| Property | Value | Notes |
|---|---|---|
| Common name | Freeze-drying | Process removes water by sublimation under vacuum. |
| Typical primary drying shelf temperature | -40 C to -10 C | Set below the formulation's collapse temperature. |
| Typical chamber pressure | 0.05-0.3 mbar | Low pressure allows ice to sublime below its triple point. |
| Water content after drying | 0.5-3% by weight | Higher values may reduce storage stability for some materials. |
| Key thermal parameter | Collapse temperature | Measured by freeze-drying microscopy or differential scanning calorimetry. |
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.
Lyophilization is a dehydration process that removes water from a frozen material by sublimation under low pressure. The material is first frozen to convert liquid water into ice. Next, the pressure is reduced below the triple point of water so that ice changes directly into vapor without passing through a liquid phase. This step is called primary drying. The result is a porous solid or cake that retains the original shape of the frozen solution.
A typical cycle begins with freezing, which fixes the material into a solid and determines ice crystal size. Primary drying then raises heat under vacuum so ice sublimes, often near or below the collapse temperature of the formulation. Secondary drying removes bound water that remains after ice is gone, usually by gently warming the product. Each stage balances heat input against pressure to avoid melting or structural damage. Temperature probes and pressure sensors guide the transition between stages.
In practice, lyophilization is slower and more energy intensive than simple drying. Cycle times can range from hours to several days depending on load, container, and formulation. Amorphous materials may require excipients that help preserve structure during freezing and drying. The method is widely used for biological materials, pharmaceuticals, and foods where heat drying would cause unacceptable change. Open questions remain about scaling cycles between laboratory and production equipment, and this gap affects technology transfer.
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== Honors == Dr. Goldstein is the recipient of several awards, including the Career Scientist Award of the Health Research Council, City of New York; the Van Dyke Memorial Award in Pharmacology from the Columbia University College of Physicians and Surgeons; the Copernicus Medal from the University of Kraków; a citation from the U.S. Department of Health, Education and Welfare "in recognition and appreciation of outstanding work in helping to establish a national program on Biological Response Modifiers"; a Doctor of Science degree (honoris causa) from Wagner College; the Decoration of the Order of Vasco Núñez de Balboa, in the rank of Commander, Panama's highest honor, for "contributions directed to the preservation of human life in the world"; the Distinguished Researcher Award of the George Washington University School of Medicine, and the Chevalier des Palmes Académiques, the highest civilian award of France. He was elected to ΑΩΑ, the National Medical Honor Society in 2007.
Casualty numbers have escalated significantly over time. According to a Stratfor report, the number of drug-related deaths in 2006 and 2007 (2,119 and 2,275) more than doubled to 5,207 in 2008. The number further increased substantially over the next two years, from 6,598 in 2009 to over 11,000 in 2010. According to data from the Mexican government, the death numbers are even higher: 9,616 in 2009, 15,273 in 2010, coming to a total of 47,515 killings between 2006 and January 2012. It is often not clear what deaths are part of the Mexican drug war versus general criminal homicides, and different sources give different estimates. Casualties are often measured indirectly by estimated total deaths from organized crime in Mexico. This amounts to about 115,000 people in the years 2007–2018. From 2018 to 2020, it was estimated that there were 11,400 reports of gang violence, and over 80% of the attacks targeted civilians, resulting in 13,000 related deaths during the period.
== F == FAIMS – High-field asymmetric waveform ion mobility spectrometry FAB – Fast atom bombardment FIB – Fast ion bombardment FD – Field desorption FFR – Field-free region FI – Field ionization FT-ICR MS – Fourier transform ion cyclotron resonance mass spectrometer FTMS – Fourier transform mass spectrometer
Sources: en.wikipedia.org
Opiates such as morphine have been used for pain relief in the United States since the 1800s, and were used during the American Civil War. Opiates soon became known as a "wonder drug" and were prescribed for a wide array of ailments, even for relatively minor treatments such as cough relief. The first published deaths from opioids start being published in The Lancet in 1892 with death reported from Godfrey's Cordial, an opium-containing syrup. Bayer began marketing heroin commercially in 1898. Beginning around 1920, however, the addictiveness was recognized, and doctors became reluctant to prescribe opiates. Heroin was made an illegal drug with the Anti-Heroin Act of 1924, in which the US Congress banned the sale, importation, or manufacture of heroin. In the 1950s, heroin addiction was still fairly uncommon among average Americans, many of whom saw it as a frightening condition. The fear extended into the 1960s and 1970s, although it became common to hear or read about drugs such as cannabis and psychedelics, which were widely used at rock concerts like Woodstock. Heroin addiction began to make the news around 1970 when rock star Janis Joplin died from an overdose. During and after the Vietnam War, addicted soldiers returned from Vietnam, where heroin was easily bought. Heroin addiction grew within low-income housing projects during the same time period. In 1971, congressmen released an explosive report, The World Heroin Problem, on the growing heroin epidemic among US servicemen in Vietnam, finding that ten to fifteen percent were addicted to heroin.
==== "Smart" hydrogel dressings ==== "Smart" hydrogels which are stimuli-responsive (i.e. thermoresponsive, bioresponsive, pH-responsive, photoresponsive, and redox-responsive) are also being produced.
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=== Vitamin B12 === Vitamin B12 is not generally present in plants but is naturally found in foods of animal origin. Lacto-ovo vegetarians can obtain B12 from dairy products and eggs, and vegans can obtain it from manufactured fortified foods (including plant-based products and breakfast cereals) and dietary supplements. A strict vegan diet avoiding consumption of all animal products risks vitamin B12 deficiency, which can lead to hyperhomocysteinemia, a risk factor for several health disorders, including anemia, neurological deficits, gastrointestinal problems, platelet disorders, and increased risk for cardiovascular diseases. The recommended daily dietary intake of B12 in the United States and Canada is 0.4 mcg (ages 0–6 months), rising to 1.8 mcg (9–13 years), 2.4 mcg (14+ years), and 2.8 mcg (lactating female). While the body's daily requirement for vitamin B12 is in microgram amounts, deficiency of the vitamin through strict practice of a vegetarian diet without supplementation can increase the risk of several chronic diseases. A 2024 randomized controlled trial conducted in Taiwan found that consuming 5 grams of roasted purple laver (nori) daily for four weeks significantly improved vitamin B12 levels in vegetarians.
In the name NAD+, the superscripted plus sign indicates the positive formal charge on one of its nitrogen atoms. Some NAD is converted into the coenzyme nicotinamide adenine dinucleotide phosphate (NADP), whose chemistry largely parallels that of NAD, though its predominant role is as a coenzyme in anabolic metabolism. NADP is a reducing agent in anabolic reactions like the Calvin cycle and lipid and nucleic acid syntheses. NADP exists in two forms: NADP+, the oxidized form, and NADPH, the reduced form. NADP is similar to nicotinamide adenine dinucleotide (NAD), but NADP has a phosphate group at the C-2′ position of the adenosyl.
Sources: en.wikipedia.org
Primary drying removes ice by sublimation at low pressure and low shelf temperature. Secondary drying removes bound water by raising the shelf temperature, often under the same vacuum. The two stages differ in the water state being removed.
Freezing determines ice crystal size, pore structure, and the concentration of solutes in remaining liquid. Faster freezing generally creates smaller ice crystals and a denser dried matrix. These features affect drying rate and reconstitution behavior.
Lyophilization reduces water content but usually leaves a small amount of water in the dried material. Some water remains bound to solids or trapped in the dried matrix. Very low water targets can require extended secondary drying, which may alter product stability.
The main change is sublimation, in which ice becomes water vapor without melting into liquid water. This occurs when the chamber pressure is held below the vapor pressure of ice while mild heat is supplied. The result is a dry, porous solid that retains much of its original shape.