cake collapse 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 2025-09-07. Where a claim depends on a specific study, the study is described rather than over-claimed.
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.
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.
Misconceptions about lyophilization include the idea that dried products are indefinitely stable or that vacuum sealing eliminates all degradation. Chemical reactions can continue in the solid state, and some proteins lose activity even at low moisture. Another misconception is that any freeze-dryer cycle can be scaled by time alone; heat and mass transfer differ with equipment and load. Open questions remain about predicting long-term stability from short accelerated studies, particularly for amorphous formulations. Real-time stability data remain the standard for shelf-life assignment.
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.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Freeze-drying, lyophilisation | Lyophilisation is the British spelling; the process is not simple evaporation. |
| Primary drying pressure | 0.05–0.3 mbar | Pressure must remain below the vapor pressure of ice at the product temperature. |
| Sublimation temperature | Below 0 °C | Ice changes directly to vapor while the product remains frozen. |
| Typical shelf temperature | −40 to −10 °C | Exact setting depends on formulation critical temperature and equipment. |
| Cycle duration | 12–72 hours | Time varies with fill volume, formulation, and dryer performance. |
Freeze-drying is distinct from simple evaporation and from spray drying. Evaporation removes water at temperatures above freezing, while spray drying rapidly dries droplets in a heated gas stream. Lyophilization avoids high temperatures, which can be useful for heat-sensitive materials such as proteins, vaccines, and some foods. The porous cake produced by sublimation dissolves or rehydrates more quickly than a dense dried mass. Not all materials tolerate freezing or the pH shifts that can occur as solutes concentrate during ice formation.
Lyophilization removes water from a frozen material by sublimation under reduced pressure. The process begins with freezing, which converts liquid water into ice and fixes the structure of the sample. After freezing, primary drying lowers pressure so ice changes directly to vapor without passing through a liquid phase. Secondary drying then removes bound water that remains after ice sublimation. The result is a dry, porous solid that often retains its original shape.
Quality assessment of a lyophilized product includes cake appearance, residual moisture, reconstitution time, and container closure integrity. A uniform, porous cake suggests that freezing and drying stayed within the formulation's design space. Cracks, shrinkage, meltback, or a glassy film can indicate thermal abuse or a formulation problem. Analysts also test for subvisible particles and sterility when the product requires those specifications. Visual inspection alone cannot confirm biological activity or chemical stability, so it is combined with analytical methods.
Stability programs monitor lyophilized products under defined temperature and humidity conditions over time. Real-time studies at recommended storage conditions are the reference, while accelerated studies provide early signals of degradation pathways. Because a dry cake can still undergo oxidation, hydrolysis, or aggregation, stability depends on residual moisture, excipients, and container headspace. Open questions include how best to predict long-term stability from short accelerated runs and how vial-to-vial variability affects shelf life. Current guidance treats these predictions as product-specific rather than universally generalizable.
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.
== Epidemiology == Studies have found the prevalence of heightened IGF-1 levels in cats with diabetes mellitus to range between 17.8% and 27.3%. According to Claudia Reusch, a professor at the University of Zurich, the prevalence of hypersomatotropism in diabetic cats is 10–15%, in cases that are hard to regulate it rises to 30% or higher.
== Track listing == "Sickman", "Junkhead", "Dirt" and "God Smack" are credited to Cantrell/Staley with no specification for lyrics or music. "Rain When I Die" is credited to Cantrell/Staley/Kinney/Starr, and it was later stated that Cantrell and Staley wrote the lyrics.
Rose Pharma is a private company that was founded in 2003 as Gastrotech Pharma and is located in Copenhagen, Denmark. The company is led by CEO Leif Helth Jensen, who is, together with Michael Forer and Florian Schönharting, also member of the Board of Directors. Rose Pharma is a clinical stage biotechnology company focused on the development of novel treatments for IBS and anorexia/cachexia associated with cancer and other major pathologies.
Jennifer Ann Kiggans (née Moore; born June 18, 1971) is an American politician, former United States Navy helicopter pilot, and geriatric nurse practitioner serving as the U.S. representative for Virginia's 2nd congressional district since 2023. A member of the Republican Party, she previously served in the Virginia Senate from 2020 to 2022. Kiggans was first elected to the House in 2022, defeating Democratic incumbent Elaine Luria. She was re-elected in 2024.
Sources: en.wikipedia.org
In January 2023, Germany ambassador to Brazil Heiko Thoms confirmed Chancellor Olaf Scholz would visit Brazil on 30 January. According to a statement, the main subjects to be addressed would be environment (including the re-establishment of the Amazon Fund) and trade between Germany and Brazil. On 30 January, Germany development minister Svenja Schulze announced the country will donate €204 million (US$222 million) to Brazil aiming to help restore farming degraded areas through low-interest rate loans, as well as it will make fresh monetary contributions to the Amazon Fund and provide local aid to Brazilian states in the Amazon region; new sustainable agriculture and green hydrogen projects in Brazil are also being looked upon by the German government, according to Schulze. During the meeting with Scholz, Lula proposed creating a group of countries, including India, Indonesia and China, that would "mediate a peace process" in the Russo-Ukrainian War. In March 2023, Germany's Vice Chancellor Robert Habeck and Agriculture Minister Cem Özdemir, as well as several German business people, attended the German-Brazilian Economic Meeting in Belo Horizonte where they met with vice-president Geraldo Alckmin.
=== Discontinued === ABT-436 – vasopressin V1b receptor antagonist – alcoholism Adrogolide (ABT-431; DAS-431) – dopamine D1 receptor agonist – cocaine-related disorders ADX-629 – aldehyde inhibitor / reactive aldehyde species (RASP) inhibitor – alcoholism, alcoholic hepatitis ADX-10061 (CEE-310; CEE-03-310; NNC-010687; NNC-687) – dopamine D1 receptor antagonist – smoking withdrawal, substance-related disorders ADX-71441 – GABAB receptor positive allosteric modulator – alcoholism, cocaine-related disorders, substance-related disorders Anatabine (RCP-006) – nicotinic acetylcholine receptor agonist – smoking withdrawal ANS-6637 (GS-6637; GS-6673) – aldehyde dehydrogenase 2 (ALDH2) inhibitor – alcoholism, opioid-related disorders, smoking withdrawal, substance-related disorders Arbaclofen placarbil (R-baclofen placarbil; XP-19986) – GABAB receptor agonist – alcoholism ASP-8062 – GABAB receptor modulator – opioid-related disorders Aticaprant (AVTX-501; CERC-501; JNJ-3964; JNJ-67953964; JNJ-67953964-AAA; LY-2456302) – κ-opioid receptor antagonist – alcoholism, cocaine-related disorders, smoking withdrawal Azasetron (nazasetron; Serotone; Y-25130) – serotonin 5-HT3 receptor antagonist – cocaine-related disorders AZD-4041 – orexin OX1 receptor antagonist – smoking withdrawal Baclofen/samidorphan (ALKS-29; ALKS-33/baclofen; baclofen/ALKS-33) – combination of baclofen (GABAB receptor agonist) and samidorphan (μ-opioid receptor antagonist) – alcoholism Befloxatone (MD-370503) – monoamine oxidase A (MAO-A) inhibitor – smoking withdrawal BP-897 – dopamine D3 receptor agonist – cocaine-related disorders BR-9003 (BR-9003A) – undefined mechanism of action – smoking withdrawal BTRX-246040 (LY-2940094) – nociceptin receptor agonist – alcoholism Buprenorphine/naloxone (NanoBUP; NTC-0510; NTC-510) – combination of buprenorphine (non-selective opioid receptor modulator) and naloxone (orally/sublingually inactive opioid receptor antagonist) – opioid-related disorders Buprenorphine/samidorphan (ALKS 33-BUP; ALKS 33/buprenorphine; ALKS-5461; BUP-ALKS 33; buprenorphine/ALKS-33; buprenorphine/RDC 0313; RDC 0313/buprenorphine; samidorphan/buprenorphine) – combination of buprenorphine (non-selective opioid receptor modulator) and samidorphan (μ-opioid receptor antagonist) – cocaine-related disorders Cannabidiol (CBD; synthetic cannabidiol; RAD-011) – cannabinoid/various actions – substance-related disorders CVL-936 – dopamine D2 and D3 receptor antagonist – substance-related disorders CX-1739 – AMPA receptor positive allosteric modulator (ampakine) – substance-related disorders Deudimethyltryptamine (HLP004; HLP-004; CYB004; CYB-004; DMT-d10; deuterated dimethyltryptamine; dDMT) – non-selective serotonin receptor agonist, serotonin 5-HT2A receptor agonist, and serotonergic psychedelic – substance-related disorders Deupsilocin (HLP003; HLP-003; CYB003; CYB-003; psilocin-d10; deuterated psilocin) – non-selective serotonin receptor agonist, serotonin 5-HT2A receptor agonist, and serotonergic psychedelic – alcoholism Dianicline (SSR-591813) – nicotinic acetylcholine receptor agonist – smoking withdrawal Drinabant (AVE-1625; INDV-5004; OPNT-004) – cannabinoid CB1 receptor antagonist – substance-related disorders Ecopipam (EBS-101; PSYRX-101; SCH-39166) – dopamine D1 receptor antagonist – cocaine-related disorders Eglumetad (eglumegad; LY-354740) – metabotropic glutamate mGlu2 and mGlu3 receptor agonist – smoking withdrawal Elinzanetant (BAY-3427080; GSK-1144814A; GSK-1144814; Lynkuet; NT-814) – neurokinin NK1 and NK3 receptor antagonist – opioid-related disorders Femoxetine (femoxitine; FG-4963; Malexil; NNC-204963) – selective serotonin reuptake inhibitor (SSRI) – alcoholism Gabapentin enacarbil (ASP8825; Gabapentin-XP; GSK-1838262; Horizant; Regnite; Solzira; XP13512) – gabapentinoid (α2δ subunit-containing voltage-gated calcium channel blocker) – alcoholism Gepirone (Ariza; BMY-13805; Exxua; MJ-13805; Org-33062; TGFK07AD; Travivo; Variza) – serotonin 5-HT1A receptor agonist – cocaine-related disorders Istradefylline (KW-6002; Nourianz; Nouriast) – adenosine A2 receptor antagonist ITI-333 – serotonin 5-HT2A receptor antagonist, dopamine D1 receptor antagonist, α1A-adrenergic receptor antagonist, μ-opioid receptor partial agonist – substance-related disorders JNJ-39393406 – α7 subunit-containing nicotinic acetylcholine receptor positive allosteric modulator – smoking withdrawal JZP-150 – fatty acid amide hydrolase (FAAH) inhibitor – alcoholism Lisdexamfetamine (LDX; Elvanse; NRP-104; S-877489; SHP-489; SPD-489; Tyvense; Venvanse; Vyvanse) – norepinephrine–dopamine releasing agent (NDRA) – cocaine-related disorders Lorcaserin (APD-356; Belviq; E2023; Venespri) – serotonin 5-HT2C receptor agonist – smoking withdrawal Manifaxine (BW-1555U88; GW-320659) – norepinephrine–dopamine reuptake inhibitor (NDRI) – smoking withdrawal Mavoglurant (AFQ-056; STP-7) – metabotropic glutamate mGlu5 receptor antagonist – smoking withdrawal Nalmefene (CPH-101; JF-1; Lu AA36143; Nalmetrene; NIH-10365; ORF-11676; Selincro; Soberal) – μ-opioid receptor antagonist, κ-opioid receptor weak partial agonist – smoking withdrawal Nepicastat oral (APL-1401; SYN-117) – dopamine β-hydroxylase (DBH) inhibitor – cocaine-related disorders Neramexane (KRP-209; MRZ-2/579) – NMDA receptor antagonist, nicotinic acetylcholine receptor antagonist – alcoholism NIC-002 (NIC002; CYT002-NicQβ; Nicotine-Qβ) – immunostimulant (nicotine vaccine) – smoking withdrawal NicVAX – immunostimulant (nicotine vaccine) – smoking withdrawal Nornicotine – nicotinic acetylcholine receptor agonist – smoking withdrawal NS-2359 (GSK-372475) – serotonin–norepinephrine–dopamine reuptake inhibitor (SNDRI) – alcoholism NYX-783 – ionotropic glutamate NMDA receptor modulator – alcoholism, opioid-related disorders OREX-1019 – μ-opioid receptor agonist, δ-opioid receptor antagonist, κ-opioid receptor antagonist, nociceptin receptor agonist – cocaine-related disorders OREX-1038 – μ-opioid receptor agonist – cocaine-related disorders, opioid-related disorders Oxytocin intranasal (Syntocinon Nasal Spray; TUR-001) – oxytocin receptor agonist – alcoholism Quetiapine (FK-949; FK949E; ICI-204636; Seroquel) – atypical antipsychotic (non-selective monoamine receptor modulator) – alcoholism Rimonabant (Acomplia; SR-141716; SR-141716A; Zimulti) – cannabinoid CB1 receptor antagonist – smoking withdrawal Risperidone (JNJ-410397-AAA; R-64766; R064766; Risperdal; Risperdal Consta; Risperdal Depot) – atypical antipsychotic (non-selective monoamine receptor modulator) – substance-related disorders RTI-113 – dopamine reuptake inhibitor (DRI) (cocaine analogue) – cocaine-related disorders Samidorphan (ALKS-33; RDC-0313; RDC-0313-00) – μ-opioid receptor antagonist – alcoholism, substance-related disorders Sembragiline (EVT-302; RG-1577; RO-4602522) – monoamine oxidase B (MAO-B) inhibitor – smoking withdrawal Serlopitant (JTS-661; MK-0594; VPD-737) – neurokinin NK1 receptor antagonist – alcoholism Surinabant (SR-147778; SR147778) – cannabinoid CB1 receptor antagonist – alcoholism, smoking withdrawal TA-NIC – immunostimulant (nicotine vaccine) – smoking withdrawal Tradipitant (LY-686017; Nereus; VLY-686) – neurokinin NK1 receptor antagonist – alcoholism Verucerfont (GSK-561679; NBI-77860) – corticotropin-releasing factor 1 (CRF1) receptor antagonist Vigabatrin (γ-vinyl-GABA; gamma-vinyl-GABA; GVG; M071754; MDL-71754; RMI-71754; Sabril; Sabrilex) – GABA transaminase (GABA-T) inhibitor – cocaine-related disorders, substance-related disorders
Muscimol is a potent GABAA receptor full agonist, activating the receptor for the brain's principal inhibitory neurotransmitter, γ-aminobutyric acid (GABA). Muscimol binds to the same site on the GABAA receptor complex as GABA itself, unlike other GABAergic drugs such as barbiturates, benzodiazepines, and Z-drugs, which interact with separate allosteric sites. GABAA receptors are widely distributed in the brain, so when muscimol is administered, it alters neuronal activity in multiple regions including the cerebral cortex, hippocampus, and cerebellum. By mimicking GABA, muscimol activates these receptors, leading to the opening of chloride channels and subsequent hyperpolarization of neurons. This results in decreased neuronal excitability, which is crucial for maintaining the balance between excitation and inhibition in the central nervous system. Muscimol was originally reported to show relatively uniform effects on GABAA receptors of differing subunit compositions. However, it was found to act as a superagonist of extrasynaptic α4β3δ subunit-containing GABAA receptors (EmaxTooltip maximal efficacy = 120 to 140% relative to GABA). This was found to be due to reduced receptor desensitization with muscimol compared to GABA. Subsequent research has found that muscimol is a preferential agonist of the relatively small population of extrasynaptic and/or δ subunit-containing GABAA receptors and that these receptors have a substantial contribution to its effects.
=== 31 March === The International Monetary Fund approved a $15.6 billion support package for Ukraine to assist with the country's economic recovery. The package would be the first of its kind for a country at war. The World Bank estimated that around US$411 billion was needed for Ukraine's recovery and for rebuilding from the invasion.
Heparin, also known as unfractionated heparin (UFH), is a medication and naturally occurring glycosaminoglycan. It is one of the most studied sulfated polysaccharides. Heparin is a blood anticoagulant that increases the activity of antithrombin. It is used in the treatment of heart attacks and unstable angina. It can be given intravenously or by injection under the skin. Its anticoagulant properties make it useful to prevent blood clotting in blood specimen test tubes and kidney dialysis machines. Common side effects include bleeding, pain at the injection site, and low blood platelets. Serious side effects include heparin-induced thrombocytopenia. Greater care is needed in those with poor kidney function. Heparin is contraindicated for suspected cases of vaccine-induced pro-thrombotic immune thrombocytopenia (VIPIT) secondary to SARS-CoV-2 vaccination, as heparin may further increase the risk of bleeding in an anti-PF4/heparin complex autoimmune manner, in favor of alternative anticoagulant medications (such as argatroban or danaparoid). Heparin appears to be relatively safe for use during pregnancy and breastfeeding. Heparin is produced by basophils and mast cells in all mammals. The discovery of heparin was announced in 1916. It is on the World Health Organization's List of Essential Medicines. A fractionated version of heparin, known as low molecular weight heparin, is also available.
Sources: en.wikipedia.org
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.
Freezing determines ice crystal size, solute distribution, and the pore network left after drying. A slow or fast freezing rate can produce different cake structures and affect reconstitution. It also sets whether the formulation follows an amorphous or crystalline drying path.
It removes most free water during primary drying and part of the bound water during secondary drying. A small residual moisture content often remains and is specified for each product. Complete removal is generally neither practical nor desirable for stability.
No. Freeze-drying removes water but does not reliably kill microorganisms. Sterile lyophilized products are typically prepared aseptically before freezing or are sterilized by a validated method. Microbial control depends on the entire manufacturing process.