The short version of primary drying fits in a sentence. The long version — which is the one that helps — is below.
This page was last updated on 2026-07-21 and is reviewed periodically as new material appears.
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.
Quality control for lyophilized materials includes visual inspection, residual moisture measurement, and reconstitution testing. Cake appearance can reveal process problems such as collapse, shrinkage, or meltback, although appearance alone does not prove potency. Residual moisture is commonly measured by Karl Fischer titration or by loss on drying. Reconstitution time is checked because a slow or incomplete dissolve can indicate a change in pore structure. Stability studies track these attributes over time under defined temperature and humidity conditions.
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.
Lyophilization, also called freeze-drying, removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts free water into ice and may also produce a glassy phase. Primary drying then lowers chamber pressure so ice sublimes directly to vapor without passing through a liquid stage. Secondary drying raises the temperature modestly to remove bound water. The result is a porous, dry solid that usually reconstitutes quickly. Each stage influences pore structure, residual moisture, and stability.
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.
| Property | Value | Notes |
|---|---|---|
| Storage temperature | 2–8 °C or 20–25 °C | Depends on product stability; some require frozen storage. |
| Moisture content | 0.5–3% w/w | Higher values may reduce stability; target set per product. |
| Moisture method | Karl Fischer titration | Coulometric for low levels; volumetric for higher levels. |
| Cake appearance | Uniform, intact, no collapse | Visual inspection is qualitative and not a potency measure. |
| Reconstitution time | Seconds to several minutes | Depends on cake density, excipients, and diluent. |
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.
Handling and storage practices aim to keep the cake intact and dry. Vials are typically stored upright at controlled temperatures, often between 2 °C and 8 °C or at -20 °C for longer-term use. Reconstitution involves adding a suitable diluent and gently mixing until the solid dissolves. Shaking or rapid injection of diluent can create foam or damage sensitive molecules. Once reconstituted, the product may require refrigeration and use within a defined period.
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.
Lyophilization is a dehydration process that removes water from a frozen material by sublimation under low pressure. The material is first frozen so that water becomes ice; then the surrounding pressure is lowered below the vapor pressure of ice. Heat is applied gently so ice changes directly to vapor without passing through a bulk liquid phase. The vapor is collected on a cold condenser, leaving a dry porous matrix. This process differs from simple evaporation because the material remains frozen during the main drying stage.
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.
Storage stability depends on water content, oxygen exposure, and temperature. Lyophilized solids are hygroscopic and can absorb water if exposed to humid air. Vials are usually sealed under vacuum or inert gas with rubber stoppers and aluminum crimps. Storage temperatures range from room temperature to refrigerated or frozen conditions depending on the material. Stability studies track potency, moisture, and physical form over time. Accelerated conditions can reveal sensitivity but may not predict long-term behavior.
Analytical methods for lyophilized materials include X-ray diffraction for crystallinity, differential scanning calorimetry for thermal transitions, and scanning electron microscopy for pore morphology. Moisture sorption analysis shows how the cake responds to humidity. These methods help distinguish amorphous from crystalline states and detect phase changes. Open questions remain about how pore structure changes during long-term storage and how best to predict collapse under varied conditions. Comparisons across studies are complicated by differences in formulation, cycle, and storage history.
== Research == Under research are GLP1 poly-agonist peptides, dual and triple receptor agonists such as tirzepatide (GLP-1 + GIP) and retatrutide (GLP-1 + GIP + glucagon), and combinations such as cagrilintide/semaglutide, which combines semaglutide with a dual amylin and calcitonin receptor agonist, and amycretin, which acts as both a GLP1 and an amylin agonist.
Research has focused on changing the mixture of keratins produced in the skin. There are 54 known keratin genes—of which 28 belong to the type I intermediate filament genes and 26 to type II—which work as heterodimers. Many of these genes share substantial structural and functional similarity, but they are specialized to cell type and/or conditions under which they are normally produced. If the balance of production could be shifted away from the mutated, dysfunctional keratin gene toward an intact keratin gene, symptoms could be reduced. For example, sulforaphane, a compound found in broccoli sprouts and few other vegetables, was found to reduce blistering in a mouse model to the point where affected pups could not be identified visually, when injected into pregnant mice (5 μmol/day = 0.9 mg) and applied topically to newborns (1 μmol/day = 0.2 mg in jojoba oil). As of 2008, clinical research at the University of Minnesota has explored allogeneic bone marrow transplantation for RD and junctional EB, treating a two-year-old child who is one of two brothers with EB. A second transplant has also been performed on the child's older brother. A Missouri boy has also successfully undergone the transplant, as well as a 5 year old boy from Alabama. So far there have been 12 successful transplants. Another transplant is scheduled for a California baby. A clinical trial is planned for 30 subjects. However, the immune suppression that bone marrow transplantation requires causes a risk of serious infections with large scale blisters and skin erosion.
=== Pharmacokinetics === Escitalopram is a substrate of P-glycoprotein and hence P-glycoprotein inhibitors such as verapamil and quinidine may improve its blood-brain barrier penetrability. In a preclinical study in rats combining escitalopram with a P-glycoprotein inhibitor, its antidepressant-like effects were enhanced.
Sources: en.wikipedia.org
== Diagnosis == Affected patients may have normal, low, or slightly elevated TSH depending on the spectrum and phase of illness. Total T4 and T3 levels may be altered by binding protein abnormalities, and medications. Reverse T3 levels are generally increased, while FT3 is decreased. FT4 levels may have a transient increase, before becoming subnormal during severe illness. Correspondingly, in the majority of cases calculated sum activity of peripheral deiodinases (SPINA-GD) is reduced. Generally the levels of free T3 will be lowered, followed by the lowering of free T4 in more severe disease. Several studies described elevated concentrations of 3,5-T2, an active thyroid hormone, in NTIS. 3,5-T2 levels were also observed to correlate with concentrations of rT3 (reverse T3) in patients with euthyroid sick syndrome. NTIS is a component of a complex endocrine adaptation process, so affected patients might also have hyperprolactinemia and elevated levels of corticosteroids (especially cortisol) and growth hormone. NTIS can be difficult to distinguish from other forms of thyroid dysfunction in the hospital setting. Both NTIS and primary hypothyroidism may have reduced fT3 and fT4, and elevated TSH (which is common in the hospital, during the recovery phase of NTIS). Prescribing thyroxine to treat this may lead to lifelong thyroid overtreatment. Hyperthyroidism may be assumed due to decreased TSH and a transient fT4 increase. In some cases, this can be distinguished from NTIS by a thyroid ultrasound, which is commonly available in the hospital intensive care unit.
Release of a C-terminal basic amino acid (lysine or arginine), preferentially lysine. This is a zinc-activated enzyme found in plasma. It inactivates proteins such as bradykinin and anaphylatoxins in the blood in order to prevent toxic buildup.
Comparatively simple devices are often used to apply counterions of increasing gradient to a chromatography column. Counterions such as copper (II) are chosen most often for effectively separating peptides and amino acids through complex formation. A simple device can be used to create a salt gradient. Elution buffer is consistently being drawn from the chamber into the mixing chamber, thereby altering its buffer concentration. Generally, the buffer placed into the chamber is usually of high initial concentration, whereas the buffer placed into the stirred chamber is usually of low concentration. As the high concentration buffer from the left chamber is mixed and drawn into the column, the buffer concentration of the stirred column gradually increase. Altering the shapes of the stirred chamber, as well as of the limit buffer, allows for the production of concave, linear, or convex gradients of counterion. A multitude of different mediums are used for the stationary phase. Among the most common immobilized charged groups used are trimethylaminoethyl (TAM), triethylaminoethyl (TEAE), diethyl-2-hydroxypropylaminoethyl (QAE), aminoethyl (AE), diethylaminoethyl (DEAE), sulpho (S), sulphomethyl (SM), sulphopropyl (SP), carboxy (C), and carboxymethyl (CM). Successful packing of the column is an important aspect of ion chromatography. Stability and efficiency of a final column depends on packing methods, solvent used, and factors that affect mechanical properties of the column.
The majority of mummies recovered in the Czech Republic come from underground crypts. While there is some evidence of deliberate mummification, most sources state that desiccation occurred naturally due to unique conditions within the crypts. The Capuchin Crypt in Brno contains three hundred years of mummified remains directly below the main altar. Beginning in the 18th century when the crypt was opened, and continuing until the practice was discontinued in 1787, the Capuchin friars of the monastery would lay the deceased on a pillow of bricks on the ground. The unique air quality and topsoil within the crypt naturally preserved the bodies over time. Approximately fifty mummies were discovered in an abandoned crypt beneath the Church of St. Procopius of Sázava in Vamberk in the mid-1980s. Workers digging a trench accidentally broke into the crypt, which began to fill with waste water. The mummies quickly began to deteriorate, though thirty-four were able to be rescued and stored temporarily at the District Museum of the Orlické Mountains until they could be returned to the monastery in 2000. The mummies range in age and social status at time of death, with at least two children and one priest. The majority of the Vamberk mummies date from the 18th century. The Klatovy catacombs currently house an exhibition of Jesuit mummies, alongside some aristocrats, that were originally interred between 1674 and 1783. In the early 1930s, the mummies were accidentally damaged during repairs, resulting in the loss of 140 bodies.
Sources: en.wikipedia.org
The major metabolite of progesterone in the urine is the 3α,5β,20α isomer of pregnanediol glucuronide, which has been found to constitute 15–30% of an injection of progesterone. Other metabolites of progesterone formed by the enzymes in this pathway include 3α-dihydroprogesterone, 3β-dihydroprogesterone, 20α-dihydroprogesterone, and 20β-dihydroprogesterone, as well as various combination products of the enzymes aside from those already mentioned. Progesterone can also first be hydroxylated (see below) and then reduced. Endogenous progesterone is metabolized approximately 50% into 5α-dihydroprogesterone in the corpus luteum, 35% into 3β-dihydroprogesterone in the liver, and 10% into 20α-dihydroprogesterone. Relatively small portions of progesterone are hydroxylated via 17α-hydroxylase (CYP17A1) and 21-hydroxylase (CYP21A2), into 17α-hydroxyprogesterone and 11-deoxycorticosterone (21-hydroxyprogesterone), respectively, and pregnanetriols are formed secondarily to 17α-hydroxylation. Even smaller amounts of progesterone may also be hydroxylated via 11β-hydroxylase (CYP11B1) and, to a lesser extent, via aldosterone synthase (CYP11B2) into 11β-hydroxyprogesterone. In addition, progesterone can be hydroxylated in the liver by other cytochrome P450 enzymes that are not steroid-specific. Catalyzed mainly by CYP3A4, 6β-Hydroxylation is the major transformation and is responsible for approximately 70% of cytochrome P450-mediated progesterone metabolism. Other routes include 6α-, 16α-, and 16β-hydroxylation.
The data are obtained within 1–2 h and include unique quality control measures through the GFP signal. DSF-GTP has been applied for the characterization of proteins and the screening of small compounds.
P. s. pv. aceris attacks maple Acer species. P. s. pv. actinidiae attacks kiwifruit Actinidia chinensis. P. s. pv. aesculi attacks horse chestnut Aesculus hippocastanum, causing bleeding canker. P. s. pv. aptata attacks beets Beta vulgaris. P. s. pv. atrofaciens attacks wheat Triticum aestivum. P. s. pv. dysoxylis attacks the kohekohe tree Dysoxylum spectabile. P. s. pv. glycinea attacks soybean Glycine max, causing bacterial blight of soybean. P. s. pv. japonica attacks barley Hordeum vulgare. P. s. pv. lapsa attacks wheat Triticum aestivum. P. s. pv. panici attacks Panicum grass species. P. s. pv. papulans attacks crabapple Malus sylvestris species. P. s. pv. persicae attacks nectarine and peach. P. s. pv. phaseolicola causes halo blight of beans. P. s. pv. pisi attacks peas Pisum sativum. P. s. pv. syringae attacks Syringa, Prunus, and Phaseolus species. P. s. pv. tomato attacks tomato. However, many of the strains for which new species groupings were proposed continue to be referred to in the scientific literature as pathovars of P. syringae, including pathovars tomato, phaseolicola, and maculicola. Pseudomonas savastanoi was once considered a pathovar or subspecies of P. syringae, and in many places continues to be referred to as P. s. pv. savastanoi, although as a result of DNA-relatedness studies, it has been instated as a new species. It has three host-specific pathovars: P. s. fraxini (which causes ash canker), P. s. nerii (which attacks oleander), and P. s. oleae (which causes olive knot).
== Veterinary use == Tapentadol has been demonstrated as a potentially effective analgesic in experimental studies however, further research is needed before it can be recommended for clinical use. Tapentadol is mainly metabolized as tapentadol-O-glucuronide in dogs and tapentadol-O-sulfate in cats. Intravenous, but not oral, administration has been shown to be effective in the dog, inducing sedation, salivation, ataxia, diarrhoea, and thermal antinociception. In cats intravenous, intramuscular, and subcutaenous administration has resulted in mild sedation and salivation. IV produced longer and greater sedation in the cat than IM and SC.
Capitalizing on the popularity of the Apollo space missions in the early 1970s, Pillsbury marketed "Food Sticks" (also known as "Space Food Sticks") for the consumer market. Fourteen individually packaged sticks were included in a box, and came in six flavors such as peanut butter, caramel, and chocolate. Food Sticks were marketed as a "nutritionally balanced between meal snack". Examples of derivative products can be found in NASA Space Center gift shops, general sweets and novelty shops, online retailers, or at Army Surplus stores. A popular example is freeze-dried ice cream. Tang, originally marketed in 1959, saw an increase in popularity in the 1960s due to its inclusion on American human space flights.
Sources: en.wikipedia.org
Most lyophilized products are stored in sealed containers at controlled temperature and humidity. Some require refrigeration, while others are stable at room temperature. Protection from light and moisture is often necessary.
Cake collapse indicates that the porous structure was lost during drying. It can result from excessive product temperature or an unsuitable formulation. Collapsed cakes may have slower reconstitution and are often rejected by visual inspection.
Residual moisture affects the chemical and physical stability of a lyophilized solid. High moisture can promote degradation, aggregation, or cake shrinkage. The acceptable range is set for each product based on stability data.
Simple drying usually removes water by evaporation from a liquid or solid, often with heat. Lyophilization first freezes the material and then removes ice by sublimation under vacuum. This avoids prolonged exposure to liquid water and high temperatures.