ChemicalBook > CAS DataBase List > Hydrocortisone

Hydrocortisone

Product Name
Hydrocortisone
CAS No.
50-23-7
Chemical Name
Hydrocortisone
Synonyms
CORTISOL;HC;HYDROCORTISONE BASE;HYDROCORTISONEACETATE;Hytone;H-Cort;Cortril;Epicort;Penecort;texacort
CBNumber
CB9756715
Molecular Formula
C21H30O5
Formula Weight
362.47
MOL File
50-23-7.mol
More
Less

Hydrocortisone Property

Melting point:
211-214 °C(lit.)
alpha 
166 º (c=1, C2H5OH 25 ºC)
Boiling point:
414.06°C (rough estimate)
Density 
1.0812 (rough estimate)
refractive index 
1.6120 (estimate)
Flash point:
220°C
storage temp. 
-20°C
solubility 
H2O: 100 mg/mL
form 
powder
color 
White
Water Solubility 
319.7mg/L(25 ºC)
Decomposition 
220 ºC
Merck 
14,4787
BRN 
1354819
Stability:
Stable, but may be light sensitive. Incompatible with strong oxidizing agents.
LogP
1.610
CAS DataBase Reference
50-23-7(CAS DataBase Reference)
NIST Chemistry Reference
Hydrocortisone(50-23-7)
EPA Substance Registry System
Hydrocortisone (50-23-7)
More
Less

Safety

Hazard Codes 
Xn
Risk Statements 
62-63
Safety Statements 
36/37
WGK Germany 
3
RTECS 
GM8925000
TSCA 
Yes
HS Code 
29372100
Hazardous Substances Data
50-23-7(Hazardous Substances Data)
Toxicity
LD50 subcutaneous in mouse: > 500mg/kg
More
Less

Hazard and Precautionary Statements (GHS)

Symbol(GHS)
Signal word
Danger
Hazard statements

H373May cause damage to organs through prolonged or repeated exposure

Precautionary statements

P202Do not handle until all safety precautions have been read and understood.

P260Do not breathe dust/fume/gas/mist/vapours/spray.

P280Wear protective gloves/protective clothing/eye protection/face protection.

P308+P313IF exposed or concerned: Get medical advice/attention.

P405Store locked up.

P501Dispose of contents/container to..…

More
Less

N-Bromosuccinimide Price

Sigma-Aldrich
Product number
NIST921A
Product name
Cortisol (Hydrocortisone)
Purity
NIST?SRM?
Packaging
1G
Price
$2600
Updated
2024/03/01
Sigma-Aldrich
Product number
H0396
Product name
Hydrocortisone-Water Soluble
Purity
BioReagent, suitable for cell culture
Packaging
100MG
Price
$125
Updated
2024/03/01
Sigma-Aldrich
Product number
C-106
Product name
Cortisol solution
Purity
1.0?mg/mL in methanol, ampule of 1?mL, certified reference material, Cerilliant?
Packaging
1mL
Price
$106
Updated
2024/03/01
Sigma-Aldrich
Product number
3867
Product name
Hydrocortisone - CAS 50-23-7 - Calbiochem
Purity
Steroid hormone of the adrenal cortex with anti-inflammatory properties.
Packaging
1g
Price
$82.8
Updated
2024/03/01
Sigma-Aldrich
Product number
386698
Product name
Hydrocortisone, Chromatographic Standard
Packaging
25mg
Price
$111
Updated
2024/03/01
More
Less

Hydrocortisone Chemical Properties,Usage,Production

Chemical Properties

crystalline white powder

Originator

Hydrocortone,MSD,US,1952

Uses

Principle glucocorticoid hormone produced by adrenal cortex. An anti-inflammatory hormone.

Uses

glucocorticoid, antiinflammatory

Uses

Cortisol, or Hydrocortisone, is a steroid hormone, more specifically a glucocorticoid, produced by the zona fasciculata of the adrenal gland. Cortisol is released in response to stress and a low level of blood glucocorticoids. Its primary functions are to increase blood sugar through gluconeogenesis; suppress the immune system; and aid in fat, protein and carbohydrate metabolism.

Definition

ChEBI: A C21-steroid that is pregn-4-ene substituted by oxo groups at positions 3 and 20 and hydroxy groups at positions 11, 17 and 21. Cortisol is a corticosteroid hormone or glucocorticoid produced by zona fasciculata of the adrenal cortex, which is a part of the adrenal gland. It is usually referred to as the "stress hormone" as it is involved in response to stress and anxiety, controlled by corticotropin-releasing hormone (CRH). It increases blood pressure and blood sugar, and reduces immun responses

Indications

Hydrocortisone (Cortizone, Cortaid, Anusol-HC, Hytone, LactiCare-HC, Sarnol HC, Penecort, Texacort, and many other branded products) may be purchased as a generic drug.

Manufacturing Process

The following example from US Patent 2,602,769 illustrates the preparation of 17-hydroxycorticosterone (compound F) from 11-desoxy-17- hydroxycorticosterone (compound S). A medium was prepared from 0.5% peptone, 2% dextrose, 0.5% soybean meal, 0.5% KH2PO4, 0.5% sodium chloride and 0.3% yeast extract in tap water. To 200 ml of this sterilized medium was added an inoculum of the vegetative mycella of Cunninghamella blakesleeana. The spores had first been transferred from a sport slant to a broth medium and the broth medium was aerobically incubated at 24°C for 24 to 72 hours in a .reciprocating shaker until the development of vegetative growth. The inoculated medium containing added vegetative mycella of Cunninghamella blakesleeana was incubated for 48 hours at 24°C following which was added 66 mg of compound S, 11-desoxy-17-hydroxycorticosterone in solution in a minimum of ethanol, and incubation was maintained for 7 hours at 24°C. The beer containing steroid was diluted with 800 ml of acetone, shaken 1 hour on a reciprocating shaker and filtered. The cake was suspended in 500 ml of acetone, shaken another hour and again filtered. The filtrates were combined and the acetone was volatilized under reduced pressure at 50°C. Acetone was then added, if necessary, to bring the concentration to 20% acetone and this resulting aqueous acetone solution was extracted five times each with one-third volume of Skellysolve B petroleum ether to remove fatty materials. These extracts were back washed two times with one-tenth volume of 20% aqueous acetone and the washings were added to the main acetone extract.
The combined acetone extracts were extracted six times with one-fourth volume of ethylene dichloride and the ethylene dichloride extract was evaporated under vacuum to leave the steroid residue. This steroid residue was taken up in a minimum of methylene chloride and applied to the top of a column packed with 30 grams of silica which had been previously triturated with 21 ml of ethylene glycol. Then various developing mixtures, saturated with ethylene glycol, were passed over the column. Cuts were made as each steroid was eluted as determined by the lowering of the absorption of light at 240 nm on the automatic chromatographic fraction cutter.
Band Solvent Tube No. (60ml) Crude Solids (mg)
1 Cyclohexane 1-4 11
2 Cyclohexane-methylene chloride 3:1 5-13 6.4 compound S
3 Cyclohexane-methylene chloride 1:1 14-16 3.0
4 Cyclohexane-methylene chloride 2:3 17-23 6.0 compound E
5 Cyclohexane-methylene chloride 1:4 24-38 12.2 compound F
6 Methylene chloride 39-59 4.8
A 7.7 mg portion of band 5 was taken up in a minimum of acetone and refrigerated until crystals separated. This cold acetone mixture was centrifuged and the supernatant liquid removed by pipette. To the remaining crystals, a few drops of ice-cold ether-acetone, three to one mixture, were added, shaken, recentrifuged and the supernatant wash liquid removed by pipette. The ether-acetone wash was repeated. The resulting crystals were dried under vacuum yielding 3.3 mg of pure compound F, 17- hydroxycorticosterone.

brand name

Acticort (Baker Norton); Ala-Cort (Del Ray); Cetacort (Healthpoint); Colocort (Paddock); Cort- Dome (Bayer); Cortef (Pharmacia & Upjohn); Cortenema (Solvay Pharmaceuticals); Cortril (Pfizer); Dermacort (Monarch); Dermacort (Solvay Pharmaceuticals); Eldecort (Valeant); Epicort (Bluline); Flexicort (Westwood- Squibb); Glycort (Heran); Hi-Cor (C & M); Hydro-Rx (X Gen); Hydrocortone (Merck); Hytone (Dermik); Hytone (Sanofi Aventis); Nutracort (Healthpoint); Penecort (Allergan); Proctocort (Monarch); Stie-Cort (Stiefel); Synacort (Medicis); Texacort (Sirius).

Therapeutic Function

Glucocorticoid

General Description

Hydrocortisone, 11β,17,21-trihydroxypregn-4-ene-3,20-dione, is the primary natural GCin humans. Despite the large number of synthetic GCs, hydrocortisone,its esters, and its salts remain a mainstay ofmodern adrenocortical steroid therapy and the standard forcomparison of all other GCs and MCs . It isused for all the indications mentioned previously.

Health Hazard

Cortisol Increases (1) protein catabolism (excepting liver) gluconeogenesis; (2) carbohydrate anabolism (liver); (3) blood sugar; (4) glucose absorption; (5) brain excitation; (6) spread of infections; (7)urinary glucose and nitrogen; (8) stress tolerance; (9) lactation; (10) water diuresis.
Regulates general adaptation syndrome, water balance, blood pressure, and hormone release.
Decreases (1) fat anabolism; (2) growth rate; (3) inflammation; (4) eosinophils; (5) lymphocytes; (6) antigen sensitivity; (7) respiratory quotient; (8) ketosis; (9) wound healing; (10) skin pigmentation; (11)RBC hemolysis.

Biological Activity

hydrocortisone is a main glucocorticoid secreted by the adrenal cortex.

Contact allergens

Hydrocortisone is the principal glucocorticoid hor- mone produced by the adrenal cortex and is used topi- cally or systemically. It belongs to the allergenic A group. Marker of allergy is tixocortol pivalate.

Biochem/physiol Actions

Product does not compete with ATP.

Mechanism of action

Hydrocortisone exhibits anti-shock, anti-allergy, and anti-inflammatory action. It raises sugar content in the blood, increases potassium secretion, and lowers sodium excretion from the body. It exhibits anti-metabolic action and reduces histamine synthesis in the body.

Clinical Use

Hydrocortisone is endogenous, and it has both glucocorticoid and mineralocorticoid activity. It is the fundamental structure by which the glucocorticoid and mineralocorticoid activities of all other corticosteroids are judged. Functional groups that are essential for both mineralocorticoid and glucocorticoid activity include the pregnane skeleton with an all-trans backbone, the ring A-en-one system (?4 -3-one ring A) and the 17β-ketol side chain (C-20-keto-C-21-hydroxy). The glucocorticoid activity is enhanced by the C-11 and C-17 hydroxyl groups. Hydrocortisone can be used to treat severe asthmatic attacks that do not respond to conventional treatment. It is available as various ester forms.

Safety Profile

Poison by

Synthesis

Hydrocortisone, 11|?,17|á,21-trihydroxypregn-4-en-3,20-dione (27.1.8), is synthesized in various ways and from various compounds containing a steroid skeleton. According to one of them, hydrocortisone is synthesized from dextropregnenolone. The double bond between C16 and C17 of dextropregnenolone is oxidized using hydrogen peroxide in a base, forming an epoxide 27.1.1. Interacting this with hydrobromic acid opens the epoxide ring, forming 16-bromo-17-hydroxydextropregnenolone (27.1.2). The resulting bromo derivative undergoes debromination by hydrogen using a palladium on carbon catalyst, and then the secondary hydroxyl group undergoes esterification using formic acid in the presence of p-toluenesulfonic acid, giving 3-formyloxy-17-hydroxydextropregnenolone (27.1.3). The resulting 3-formyloxy- 17-hydroxydextropregnenolone undergoes bromination by bromine, which results in bromination of the C4¨CC5 double bond and the methyl group of acetyl moiety, which forms a tribromo derivative 27.1.4. Reacting the product with sodium iodide results in dehalogenation of the resulting vicinal dibromide, during which the double bond is simultaneously shifted into the position between carbon atoms C5 and C6 that gives the bromoketone 27.1.5. This is reacted with potassium acetate and then with acetic anhydride in the presence of p-toluenesulfonic acid, forming a diacetate 27.1.6. Taking into account that unlike acetates, formates are easily oxidized and give exactly the same products as do the corresponding alcohols, the resulting diacetate is oxidized in an Oppenauer oxidation reaction, using aluminum isopropoxide and cyclohexanone as a hydrogen acceptor. During this, isomerization of the double bond into the primary position between C4 and C5 simultaneously takes place, forming a stable, conjugated vinylketone, after which the acetyl protection of both hydroxyl groups is hydrolyzed using potassium hydroxide, giving 17-hydroxy-11-deoxycorticosterone (27.1.7). This undergoes microbiological oxidation at position C1, forming the desired hydrocortisone (27.1.8). Side reactions of microbiological oxidation using the very same microorganisms can cause hydroxylation of steroids in different positions, using easily accessible progesterone as an initial substance.

Veterinary Drugs and Treatments

Because of its rapid effect and relatively high mineralocorticoid effect, hydrocortisone sodium succinate (Solu-Cortef?) is the most commonly used form of this medication when an acute glucocorticoid/ mineralocorticoid effect is desired (e.g., acute adrenal insufficiency). Corticosteroids have not been shown beneficial in treating hypovolemic shock, but low dose glucocorticoids probably reduce mortality associated with septic shock.
Glucocorticoids have been used in an attempt to treat practically every malady that afflicts man or animal, but there are three broad uses and dosage ranges for use of these agents. 1) Replacement of glucocorticoid activity in patients with adrenal insufficiency, 2) as an antiinflammatory agent, and 3) as an immunosuppressive. Among some of the uses for glucocorticoids include treatment of: endocrine conditions (e.g., adrenal insufficiency), rheumatic diseases (e.g., rheumatoid arthritis), collagen diseases (e.g., systemic lupus), allergic states, respiratory diseases (e.g., asthma), dermatologic diseases (e.g., pemphigus, allergic dermatoses), hematologic disorders (e.g., thrombocytopenias, autoimmune hemolytic anemias), neoplasias, nervous system disorders (increased CSF pressure), GI diseases (e.g., ulcerative colitis exacerbations), and renal diseases (e.g., nephrotic syndrome). Some glucocorticoids are used topically in the eye and skin for various conditions or are injected intra-articularly or intra-lesionally. The above listing is certainly not complete.

target

TNF-α | IL Receptor | AP-1 | MMP(e.g.TIMP) | NF-kB | IkB | IKK

storage

Store at RT

Purification Methods

Recrystallise hydrocortisone from EtOH or isoPrOH. It is bitter tasting and has UV with max at 242 nm (log 4.20). Its solubility at 25o is: H2O (0.28%), EtOH (1.5%), MeOH (0.62%), Me2CO (0.93%), CHCl3 (0.16%), propylene glycol (1.3%) and Et2O (0.35%). It gives an intense green colour with conc H2SO4. [Wendler et al. J Am Chem Soc 72 5793 1950, Beilstein 8 IV 3422.]

More
Less

Hydrocortisone Suppliers

LGM Pharma
Tel
1-(800)-881-8210
Fax
615-250-9817
Email
inquiries@lgmpharma.com
Country
United States
ProdList
2123
Advantage
70
MedChemexpress LLC
Tel
021-58955995
Fax
609-228-5909
Email
sales@medchemexpress.cn
Country
United States
ProdList
4861
Advantage
58
AdooQ BioScience, LLC
Tel
+1 (866) 930-6790
Fax
+1 (866) 333-9607
Email
info@adooq.com
Country
United States
ProdList
2782
Advantage
58
HBCChem, Inc.
Tel
+1-510-219-6317
Fax
+1-650-486-1361
Email
sales@hbcchem.com
Country
United States
ProdList
10648
Advantage
60
EMMX Biotechnology LLC
Tel
888-539-0666
Fax
888-539-0666
Email
info@emmx.com
Country
United States
ProdList
8447
Advantage
60
Target molecule Corp.
Tel
857-239-0968
Fax
857-239-8801
Email
service1@targetmol.com
Country
United States
ProdList
2559
Advantage
60
TargetMol Chemicals Inc.
Tel
+1-781-999-5354 +1-00000000000
Email
marketing@targetmol.com
Country
United States
ProdList
32161
Advantage
58
InvivoChem
Tel
+1-708-310-1919 +1-13798911105
Fax
708-557-7486
Email
sales@invivochem.cn
Country
United States
ProdList
6391
Advantage
58
Standardpharm Co. Ltd.
Tel
86-714-3992388
Email
overseasales1@yongstandards.com
Country
United States
ProdList
14332
Advantage
58
Cato Research Chemicals Inc.
Tel
020-81215950 4000-868-328
Email
customer@uwalab.com
Country
United States
ProdList
10404
Advantage
58
Protheragen-ING
Tel
+16313385890
Email
info@protheragen-ing.com
Country
United States
ProdList
3868
Advantage
58
Aladdin Scientific
Tel
+1-+1(833)-552-7181
Email
sales@aladdinsci.com
Country
United States
ProdList
57505
Advantage
58
Aceschem Inc.
Tel
+1-817863-6948 +1-(817)863-6948
Email
sales@aceschem.com
Country
United States
ProdList
19632
Advantage
58
ApexBio Technology
Tel
--
Fax
--
Email
sales@apexbt.com
Country
United States
ProdList
6251
Advantage
58
Abcam
Tel
--
Fax
--
Email
us.orders@abcam.com
Country
United States
ProdList
6000
Advantage
50
Cayman Chemical Company
Tel
--
Fax
--
Email
cayman@caymanchem.com
Country
United States
ProdList
6213
Advantage
81
IsoSciences
Tel
--
Fax
--
Email
info@isosciences.com
Country
United States
ProdList
379
Advantage
58
ZETA Pharmaceuticals, L.L.C.
Tel
--
Fax
--
Email
zeta@zetapharm.com
Country
United States
ProdList
102
Advantage
58
Advanced Compounds International. (ACI)
Tel
--
Fax
--
Email
info@advancedcompounds.com
Country
United States
ProdList
74
Advantage
58
Dastech International Inc.
Tel
--
Fax
--
Country
United States
ProdList
78
Advantage
58
RTM Pharmaceuticals, L.L.C.
Tel
--
Fax
--
Email
jlevi@rtmpharma.com
Country
United States
ProdList
41
Advantage
58
Flavine North America, Inc.
Tel
--
Fax
--
Email
flavine-northamerica@flavine.com
Country
United States
ProdList
84
Advantage
58
Camphor Technologies Inc.
Tel
--
Fax
--
Country
United States
ProdList
148
Advantage
58
Selleck Chemicals LLC
Tel
--
Fax
--
Email
sales@selleckchem.com
Country
United States
ProdList
1848
Advantage
58
American International Chemical LLC.
Tel
--
Fax
--
Email
info@aicma.com
Country
United States
ProdList
90
Advantage
58
Redox Scientific
Tel
--
Fax
--
Email
info@redoxsci.com
Country
United States
ProdList
2380
Advantage
58
Bayville Chemical Supply Company Inc.
Tel
--
Fax
--
Email
info@bayvillechemical.net
Country
United States
ProdList
34
Advantage
58
Alfa Chem
Tel
--
Fax
--
Email
alfachem@gmail.com
Country
United States
ProdList
226
Advantage
58
International Specialty Chemicals & Pharmaceuticals, Inc. (ISC&P)
Tel
--
Fax
--
Email
info@ischem.com
Country
United States
ProdList
77
Advantage
58
Albany Molecular Research Inc. (AMRI)
Tel
--
Fax
--
Email
Customerservice@amriglobal.com
Country
United States
ProdList
61
Advantage
58
ICC Chemical Corporation (a subsidiary of ICC Industries Inc.)
Tel
--
Fax
--
Email
fkt@iccchem.com
Country
United States
ProdList
113
Advantage
58
Pfizer CentreOne
Tel
--
Fax
--
Email
pfizercentreone@pfizer.com
Country
United States
ProdList
14
Advantage
58
Rochem International Inc.
Tel
--
Fax
--
Email
gcadioli@rochemintl.com
Country
United States
ProdList
80
Advantage
58
Lalilab, Inc
Tel
--
Fax
--
Email
info@lalilab.com
Country
United States
ProdList
69
Advantage
58
Pharmax NA Inc.
Tel
--
Fax
--
Email
info@pharmaxus.com
Country
United States
ProdList
127
Advantage
58
Napp Technologies, LLC
Tel
--
Fax
--
Email
customer.service@napptech.com
Country
United States
ProdList
57
Advantage
58
OChem Incorporation
Tel
--
Fax
--
Email
sales@ocheminc.com
Country
United States
ProdList
6501
Advantage
60
Genegobio Inc.
Tel
--
Fax
--
Email
mark@genegobio.com
Country
United States
ProdList
195
Advantage
0
Oakwood Products, Inc.
Tel
--
Fax
--
Email
sales@oakwoodchemical.com
Country
United States
ProdList
6193
Advantage
74
ACIC Fine Chemicals Inc.
Tel
--
Fax
--
Email
sales@acic.com
Country
United States
ProdList
492
Advantage
48
Allyson Enterprises, Inc.
Tel
--
Fax
--
Email
info@allysonenterprises.com
Country
United States
ProdList
7
Advantage
58
Asiamerica Ingredients, Inc.
Tel
--
Fax
--
Email
info@asiamericaingredients.com
Country
United States
ProdList
99
Advantage
0
Spectrum Chemical Mfg. Corp.
Tel
--
Fax
--
Email
marketing@spectrumchemical.com
Country
United States
ProdList
3113
Advantage
60
Chemceed Corportaion
Tel
--
Fax
--
Email
inquiry@chemceed.com
Country
United States
ProdList
175
Advantage
50
Glentham Life Sciences Ltd
Tel
--
Fax
--
Email
info@glentham.com
Country
United States
ProdList
2026
Advantage
58
American International Chemical, Inc.
Tel
--
Fax
--
Email
info@aicma.com
Country
United States
ProdList
531
Advantage
58
Penta International Corporation
Tel
--
Fax
--
Email
lisaa@pentamfg.com
Country
United States
ProdList
5042
Advantage
58
Pharmacia & Upjohn Company
Tel
--
Fax
--
Country
United States
ProdList
3
Advantage
58
MedChemExpress
Tel
--
Fax
--
Email
sales@medchemexpress.com
Country
United States
ProdList
6398
Advantage
58
SANOFI CHIMIE
Tel
--
Fax
--
Email
johnd@sanofi.com
Country
United States
ProdList
34
Advantage
58
More
Less

View Lastest Price from Hydrocortisone manufacturers

Sinoway Industrial co., ltd.
Product
Hydrocortisone 50-23-7
Price
US $0.00-0.00/Kg/Bag
Min. Order
1Kg/Bag
Purity
0.99
Supply Ability
20 tons
Release date
2024-06-27
Henan Suikang Pharmaceutical Co.,Ltd.
Product
Hydrocortisone 50-23-7
Price
US $0.00/kg
Min. Order
5kg
Purity
97.0%~103.0%
Supply Ability
1tons
Release date
2024-04-26
Hebei Zhuanglai Chemical Trading Co Ltd
Product
Hydrocortisone 50-23-7
Price
US $150.00/kg
Min. Order
1kg
Purity
99%
Supply Ability
500kg
Release date
2024-11-26

50-23-7, HydrocortisoneRelated Search:


  • Hydrocortisone - CAS 50-23-7 - Calbiochem
  • Hydrocortisone, Chromatographic Standard - CAS 50-23-7 - Calbiochem
  • Hydrocortisone Acetate Impurity?A
  • Prednisolone Impurity 1(Prednisolone EP Impurity A)
  • Prednisolone EP Impurity A
  • 21-Trihydroxypregn-4-ene-3
  • compoundf(kendall)
  • Cortanal
  • Cort-Dome
  • Cortenema
  • Corticreme
  • Cortifan
  • Cortiment
  • Cortisol alcohol
  • cortisolalcohol
  • Cortispray
  • Cortolotion
  • Cortonema
  • Cortoxide
  • Cortril
  • Cremesone
  • Delacort
  • demacort
  • Dermacort
  • Dermolate
  • Dihydrocostisone
  • dome-cort
  • Domolene-HC
  • Ef corlin
  • Efcorbin
  • Hidro-Colisona
  • hvb
  • Hycort
  • Hycortol
  • Hycortole
  • Hydrasson
  • Hydro-Adreson
  • Hydro-colisona
  • Hydrocorticosterone
  • Hydrocortisone alcohol
  • Hydrocortisone free alcohol
  • hydrocortisonefreealcohol
  • Hydrocortisyl
  • Hydroxycortisone
  • Hytone
  • Hytone lotion
  • hytonelotion
  • Incortin-H
  • Incortin-hydrogen
  • Komed HC
  • Lacticare-HC
  • lubricort
  • Maintasone
  • meusicort
  • NSC 10483
  • nsc10483
  • Nutracort
  • Optef