AMPK

Without affecting LKB1 activity, phenformin increases the phosphorylation and activation of AMPKalpha1 and AMPKalpha2. [1] In the isolated heart, phenformin increases AMPK activity and phosphorylation; the increase in AMPK activity is always preceded by and correlated with increased cytosolic [AMP]. [2] In comparison to metformin, phenformin has a 50-fold higher inhibitory potency of mitochondrial complex I. In LKB1 deficient NSCLC cell lines, phenformin strongly induces apoptosis. Increased P-AMPK and P-Raptor levels demonstrate that phenformin at 2 mM similarly induces AMPK signaling. Higher levels of cellular stress brought on by phenformin result in the later induction of P-Ser51 eIF2, its downstream target CHOP, and markers of apoptosis. Following prolonged treatment with phenformin, KLluc mice exhibit a significantly higher rate of survival and therapeutic response.[3] AICAR and phenformin both increase AMPK activity in H441 cells in a dose-dependent manner, with maximal stimulation occurring at 2 mm and 5-10 mm, respectively. Phenformin significantly reduces basal ion transport across H441 monolayers by about 50% compared to controls (measured as short circuit current). AICAR and phenformin both significantly lower amiloride-sensitive transepithelial Na+ transport than controls. Through the activation of AMPK and the inhibition of apical Na+ entry through ENaC and basolateral Na+ extrusion through the Na+,K+-ATPase, phenformin and AICAR inhibit amiloride-sensitive Na+ transport across H441 cells.[4] A tendency for a drop in blood insulin levels is seen in phenformin-treated rats (radioimmunoassay).[5]

Phenformin also increases levels of P-eIF2α and its target BiP/Grp78 in normal lung as well as in lung tumors of mice.[3]

Total AMPK activity is measured using the method of Dagher et al. AMPK activity is quantified in the resuspended pellet as incorporation of32P from [γ-32P]ATP (10 GBq/mmol) into a synthetic peptide with the specific target sequence for AMPK, the SAMS peptide. Radioactivity is measured using a liquid scintillation counter. Protein content in the solution containing the resupended (NH4)2SO4pellet is determined using the Bradford method.

Phenformin and AICAR increases AMPK activity in H441 cells in a dose-dependent fashion, stimulating the kinase maximally at 5-10 mm and 2 mm, respectively. Phenformin significantly decreases basal ion transport (measured as short circuit current) across H441 monolayers by approximately 50% compared with that of controls. Phenformin and AICAR significantly reduce amiloride-sensitive transepithelial Na+ transport compared with controls. Phenformin and AICAR suppress amiloride-sensitive Na+transport across H441 cells via a pathway that includes activation of AMPK and inhibition of both apical Na+ entry through ENaC and basolateral Na+extrusion via the Na+,K+-ATPase[4].Phenformin-treated rats reveals a tendency towards a decrease in blood insulin level (radioimmunoassay).

Mice;

Absorption, Distribution and Excretion
PHENFORMIN IS ADEQUATELY ABSORBED FROM GI TRACT. DRUG HAS SHORT T/2 (3 HR) & CORRESPONDINGLY BRIEF DURATION OF ACTION. HYPOGLYCEMIC EFFECT MAY BE PROLONGED TO BETWEEN 6 & 14 HR WITH USE OF TIMED-DISINTEGRATION CAPSULES.
(14)C-LABELED PHENFORMIN ADMIN TO RATS (100 MG/KG ORALLY OR IP) & GUINEA PIGS (25 MG/KG ORALLY & 12.5 IP). EXCRETION OF RADIOACTIVITY & METAB WAS SLOWER IN GUINEA PIGS WHICH MAY PARTLY EXPLAIN THE INCR PHARMACOLOGICAL RESPONSE OF GUINEA PIGS TO PHENFORMIN.
RATS ELIMINATED 26% OF AN INTRADUODENAL DOSE OF LABELED PHENFORMIN (20 MG/KG) IN BILE IN 6 HR COMPARED TO 6% IN GUINEA PIG.
IN 8 DIABETIC PT HALF-LIFE OF PHENFORMIN WAS UNRELATED TO DEGREE OF RENAL IMPAIRMENT, WHEREAS REDUCED RENAL CLEARANCES OF INSULIN & CREATININE WERE SIGNIFICANTLY CORRELATED WITH PROLONGED HALF-LIFE OF ITS METABOLITE P-HYDROXYPHENETHYLBIGUANIDE.

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Metabolism / Metabolites
IN RATS & GUINEA PIGS, MAJOR METABOLITE OF PHENFORMIN, N(1)-BETA-PHENETHYLBIGUANIDE, IS N(1)-P-HYDROXY-BETA-PHENETHYLBIGUANIDE, & CORRESPONDING O-ETHER GLUCURONIDE HAS ALSO BEEN DETECTED.
METAB IN RATS & GUINEA PIGS. RATS EXCRETED LARGE AMT OF 4-HYDROXYPHENFORMIN (FREE & GLUCURONIC ACID CONJUGATED) & SOME UNCHANGED PHENFORMIN. METAB VARIED WITH DOSE & ROUTE OF ADMIN. GUINEA PIGS EXCRETED SMALL AMT OF 4-HYDROXYPHENFORMIN AFTER IP ADMIN & NONE AFTER ORAL ADMIN.
LABELED COMPD WAS ADMIN. AN UNIDENTIFIED METAB & ITS GLUCURONIDE, WHICH MAY RESULT FROM ALIPHATIC C- OR N-HYDROXYLATION, ACCOUNTED FOR 47% OF 24-HR URINARY RADIOACTIVITY (17% OF DOSE) FOLLOWING ORAL ADMIN TO GUINEA PIGS.
26 HR FOLLOWING ADMIN OF SINGLE DOSE OF PHENFORMIN, 50 MG/KG ORALLY, P-HYDROXYPHENFORMIN WAS MAJOR URINARY METAB IN PHENOTYPICALLY EXTENSIVE METABOLIZERS, BUT WAS NOT OBSERVED IN PHENOTYPICALLY POOR METABOLIZERS.
METAB IN 8 DIABETIC PT WITH RENAL IMPAIRMENT. EXCRETION OF THE METAB P-HYDROXYPHENETHYLBIGUANIDE WAS VARIABLE (BETWEEN 4.9% & 27% OF TOTAL URINARY DOSE LOSS) PROBABLY DUE TO GENETIC POLYMORPHISM OF HEPATIC MECHANISMS FOR HYDROXYLATION.
Phenformin has known human metabolites that include p-Hydroxyphenylethylbiguanide.

Interactions
PHENFORMIN HAS BEEN REPORTED...TO ENHANCE ACTIVITY OF WARFARIN. PROPOSED MECHANISM IS INCR FIBRINOLYTIC EFFECT CAUSED BY PHENFORMIN SEEN DURING FIRST FEW MO OF TREATMENT.
USE OF PROPRANOLOL IN DIABETIC PT...CAN RESULT IN DISTURBANCE OF CARBOHYDRATE METABOLISM & SHOULD BE AVOIDED. IF INSULIN & PROPRANOLOL...GIVEN CONCURRENTLY, PERIODIC SERUM GLUCOSE LEVELS SHOULD BE DETERMINED. ...SIMILAR PRECAUTIONS...APPLICABLE TO CONCURRENT USE OF...PHENFORMIN.
DIABETIC PT TREATED WITH PHENFORMIN SHOULD AVOID INGESTION OF ALCOHOLIC BEVERAGES BECAUSE CONCURRENT USE MAY CAUSE HYPOGLYCEMIC REACTIONS OR LEAD TO LIFE-THREATENING LACTIC ACIDOSIS WITH SHOCK.
DIPHENYLHYDANTOIN GIVEN IP TO RATS DECR LIVER LEVELS OF THIAMIN, RIBOFLAVIN, NIACIN, & PANTOTHENIC ACID. HEPATIC THIAMIN CONTENT WAS NORMALIZED BY SIMULTANEOUS ADMIN OF EITHER ACETOHEXAMINE OR PHENFORMIN.
For more Interactions (Complete) data for PHENFORMIN (6 total), please visit the HSDB record page.

[1]. Activity of LKB1 and AMPK-related kinases in skeletal muscle: effects of contraction, phenformin, and AICAR. Am J Physiol Endocrinol Metab.?2004 Aug;287(2):E310-7.

[2]. Metformin and phenformin activate AMP-activated protein kinase in the heart by increasing cytosolic AMP concentration. Am J Physiol Heart Circ Physiol. 2007 Jul;293(1):H457-66.

[3]. Thalidomide exerts its inhibitory action on tumor necrosis factor alpha by enhancing mRNA degradation. J Exp Med. 1993 Jun 1;177(6):1675-80.

[4]. Phenformin and 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR) activation of AMP-activated protein kinase inhibits transepithelial Na+ transport across H441 lung cells. J Physiol. 2005 Aug 1;566(Pt 3):781-92. Epub 2005.

[5]. Inhibition of DMBA-induced carcinogenesis by phenformin in the mammary gland of rats. Arch Geschwulstforsch. 1978;48(1):1-8.

Phenformin is a member of the class of biguanides that is biguanide in which one of the terminal nitrogen atoms is substituted by a 2-phenylethyl group. It was used as an anti-diabetic drug but was later withdrawn from the market due to potential risk of lactic acidosis. It has a role as an antineoplastic agent, a geroprotector and a hypoglycemic agent. It is functionally related to a biguanide.
A biguanide hypoglycemic agent with actions and uses similar to those of metformin. Although it is generally considered to be associated with an unacceptably high incidence of lactic acidosis, often fatal, it is still available in some countries. (From Martindale, The Extra Pharmacopoeia, 30th ed, p290)
Phenformin is an agent belonging to the biguanide class of antidiabetics with antihyperglycemic activity. Phenformin is not used clinically due to the high risk of lactic acidosis that is associated with its use.
A biguanide hypoglycemic agent with actions and uses similar to those of METFORMIN. Although it is generally considered to be associated with an unacceptably high incidence of lactic acidosis, often fatal, it is still available in some countries. (From Martindale, The Extra Pharmacopoeia, 30th ed, p290)

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Drug Indication
For the reatment of type II diabetes mellitus.

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Mechanism of Action
Phenformin binds to the AMP-activated protein kinase (AMPK). AMPK is an ultra-sensitive cellular energy sensor that monitors energy consumption and down-regulates ATP-consuming processes when activated. The biguanide phenformin has been shown to independently decrease ion transport processes, influence cellular metabolism and activate AMPK. Phenformin's hypoglycemic activity is related the effect it has in activating AMPK and fooling insulin sensitive cells into thinking that insulin levels are low and causing the body to use glucose as if in a state of low caloric consumption. This drug also seems to inhibit several varients of ATP-sensitive potassium channels (namely the receptor subtype Kir6.1).
IN VITRO, PHENFORMIN, IN RELATIVELY LARGE DOSES, INCR GLUCOSE UTILIZATION BY ENHANCING ANAEROBIC GLYCOLYSIS. THIS IS THOUGHT TO OCCUR AS RESULT OF, OR COINCIDENT WITH, INHIBITION OF CELLULAR RESPIRATION. ...ADENOSINE TRIPHOSPHATE (ATP) CONCN FALL & THOSE OF LACTATE INCR. SECOND ACTION OF DRUG IS TO DECR GLUCONEOGENESIS.
...MOST RECENTLY RECOGNIZED IS INHIBITION OF INTESTINAL ABSORPTION OF GLUCOSE & PROBABLY CERTAIN OTHER SUBSTANCES AS WELL; FOR EXAMPLE, DECR ABSORPTION OF VITAMIN B12 HAS BEEN OBSERVED. ...DOES NOT ACT IN NORMAL SUBJECT...PRESUMABLY BECAUSE INCR IN PERIPHERAL GLUCOSE UTILIZATION IS COMPENSATED FOR BY INCR HEPATIC GLUCOSE...
BIGUANIDES APPARENTLY LOWER BLOOD SUGAR INDIRECTLY BY INHIBITING GLUCONEOGENESIS & INCR INSULIN SENSITIVITY. /ORAL HYPOGLYCEMICS/
They induce and increase in peripheral glucose utilization, a decrease in hepatic gluconeogenesis, and a decrease in intestinal absorption of glucose, vitamin B, and bile acids. /Biguanides/
Phenformin generally lowers the blood sugar only in the diabetic patient; it also depresses the blood sugar level in a nutritionally starved individual but not in one who is well fed. In its usual dose administered to a healthy individual, phenformin does not induce lactic acidosis. Phenformin requires insulin for its action, but does not induce and elevation in plasma insulin levels.

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Therapeutic Uses
Hypoglycemic Agents
EXPTL USE: PHENFORMIN (2 MG) ADMIN 5 DAYS/WK TO C3H/SN MICE FROM AGE 3.5 MO UNTIL DEATH DECR THE NUMBER OF SPONTANEOUS TUMORS 4.0 FOLD & AVG SURVIVAL OF ANIMALS BY 100 DAYS.
IF PT REQUIRES MORE THAN 40 UNITS OF INSULIN/DAY, HE IS UNLIKELY TO RESPOND TO PHENFORMIN. ...PHENFORMIN PLUS ESTROGENS HAVE BEEN USED WITH SUCCESS IN REDUCING MORTALITY IN SURVIVORS OF MYOCARDIAL INFARCTION.
PHENFORMIN IS USED IN TREATMENT OF MATURITY-ONSET DIABETES...
For more Therapeutic Uses (Complete) data for PHENFORMIN (8 total), please visit the HSDB record page.

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Drug Warnings
IN PRESENCE OF RENAL GLYCOSURIA, FATAL HYPOGLYCEMIA CAN OCCUR.
IRREVERSIBLE LACTIC ACIDOSIS OCCURRED IN TWO PATIENTS UNDERGOING PHENFORMIN THERAPY FOR DIABETES.
PHENFORMIN...ANTIDIABETIC AGENT TAKEN ORALLY, IS REPORTED TO HAVE CAUSED TRANSITORY MYOPIA IN 53-YR-OLD DIABETIC PATIENTS.
DIABETIC SUBJECTS WITH SEVERE HEPATIC OR RENAL INSUFFICIENCY OR CONGESTIVE HEART FAILURE ARE NOT SUITABLE CANDIDATES FOR ORAL HYPOGLYCEMIC THERAPY. ...ITS ADMIN DURING PREGNANCY IS CURRENTLY NOT RECOMMENDED.
For more Drug Warnings (Complete) data for PHENFORMIN (11 total), please visit the HSDB record page.

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Pharmacodynamics
Used to treat diabetes, phenformin is a biguanide (contains 2 guanidino groups) hypoglycemic agent with actions and uses similar to those of metformin (Glucophage). Both drugs work by (1) decreasing the absorption of glucose by the intestines, (2) decreasing the production of glucose in the liver, and by (3) increasing the body's ability to use insulin more effectively. More specifically, phenformin improves glycemic control by improving insulin sensitivity. Phenformin is generally considered to be associated with an unacceptably high incidence of actic acidosis. In general biguanides should be used only in stable type II diabetics who are free of liver, kidney and cardiovascular problems and who cannot be controlled with diet.

C10H15N5

205.2596

241.109

C, 49.69; H, 6.67; Cl, 14.67; N, 28.97

834-28-6

Phenformin;114-86-3;Phenformin-d5 hydrochloride

8249

White to off-white solid powder

1.24 g/cm3

413.7ºC at 760 mmHg

175-178ºC

204ºC

2.72

3

1

4

15

236

0

Cl.N=C(NC(NCCC1C=CC=CC=1)=N)N

YSUCWSWKRIOILX-UHFFFAOYSA-N

InChI=1S/C10H15N5.ClH/c11-9(12)15-10(13)14-7-6-8-4-2-1-3-5-8;/h1-5H,6-7H2,(H6,11,12,13,14,15);1H

1-(diaminomethylidene)-2-(2-phenylethyl)guanidine;hydrochloride

W-104144; ST-50409947; D-08352; W104144; ST50409947; D08352; W 104144; ST 50409947; D 08352; Phenformin Hydrochloride; Phenformin HCl; Meltrol; Dipar; Phenethylbiguanide hydrochloride;

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

DMSO: ~48 mg/mL (~198.6 mM)
Water: ~48 mg/mL (~198.6 mM)
Ethanol: ~12 mg/mL (~49.6 mM)

Solubility in Formulation 1: ≥ 0.42 mg/mL (1.74 mM) (saturation unknown) in 10% DMSO + 40% PEG300 + 5% Tween80 + 45% Saline (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 4.2 mg/mL clear DMSO stock solution to 400 μL PEG300 and mix evenly; then add 50 μL Tween-80 to the above solution and mix evenly; then add 450 μL normal saline to adjust the volume to 1 mL.
Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH₂ O to obtain a clear solution.

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Solubility in Formulation 2: ≥ 0.42 mg/mL (1.74 mM) (saturation unknown) in 10% DMSO + 90% (20% SBE-β-CD in Saline) (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 4.2 mg/mL clear DMSO stock solution to 900 μL of 20% SBE-β-CD physiological saline solution and mix evenly.
Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.

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Solubility in Formulation 3: ≥ 0.42 mg/mL (1.74 mM) (saturation unknown) in 10% DMSO + 90% Corn Oil (add these co-solvents sequentially from left to right, and one by one), clear solution.
For example, if 1 mL of working solution is to be prepared, you can add 100 μL of 4.2 mg/mL clear DMSO stock solution to 900 μL of corn oil and mix evenly.

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Solubility in Formulation 4: 2.5 mg/mL (10.34 mM) in PBS (add these co-solvents sequentially from left to right, and one by one), clear solution; with ultrasonication (<60°C).

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 (Please use freshly prepared in vivo formulations for optimal results.)