1. Curso Internacional de Síndrome Metabólico
Dr. Alejandro Romero Zazueta
Endocrinólogo
Maestro en Ciencias Médicas Ciudad de México, 13 de agosto 2015
Uso de Metformina en Enfermedad Renal Crónica
2. Agenda
Relevancia de biguanidas, en particular metformina, en el tratamiento
farmacológico de la diabetes mellitus tipo 2.
Breves características farmacológicas de biguanidas
Estatificación de enfermedad renal crónica y acidosis láctica
Asociación de metformina a acidosis láctica: frecuencia, mecanismo y
Relevancia en Enfermedad renal crónica basadas en modelos fármaco
lógicos y evidencias clínicas disponibles.
Posturas y recomendaciones de asociaciones académicas
Recomendaciones generales para el uso de metformina en ERC
3. Objetivos
1. Establecer la frecuencia e impacto en a clínica de la
acidosis láctica asociada a metformina.
2. Conocer el perfil de seguridad del uso de metformina
en los diferentes estados en enfermedad renal crónica
6. Metformina
Cómo funciona • Disminuye la producción de glucosa
hepática
• Reduce la glucemia en ayunas
Reducción de
HbA1c esperada
~ 1,5%
Eventos adversos • Efectos secundarios sobre el índice
glucémico (GI)
• Acidosis láctica
Efectos sobre el
peso
Estabilidad en el peso o una pérdida de
peso modesta
Efectos
cardiovasculares
Efecto beneficioso no confirmado
demostrado en el estudio UKPDS
Nathan DM et al. Diabetes Care 2006;29(8):1963-72.
8. Uso amplio en Europa y USA desde 1950´s
Retirada de USA en 1976 por asociación con
acidosis láctica fatales y no fatales
Park R .Ann int Med 1977
Arief AL Clin Endocrinol Metab 1983
9. Acidosis metabólica de brecha de aniones con concentración de
lactato en plasma > 45mg/dl y PH < 7.35
Casos severos asociada a disfunción multisistémica:
Neurológica: estupor, coma
Cardiovascular: Hipotensión, fibrilación ventricular
Asociada a una tasa alta de mortalidad (75%)
Media de sobrevida en pacientes con AL y shock: 28 Hr
Acidosis láctica
10. Acidosis láctica tipo A
Pobre perfusión tisular y oxigenación sanguínea
Sobreproducción de lactato: Enf. circulatorias, pulmonares y de Hb
Infrautilización de lactato: enf.hepática severa, inh.gluconeogénesis
Acidosis láctica tipo B
B1: ERC , insuficiencia hepática, sepsis, cáncer
B2: Fármacos y toxinas
B3: Defectos congénitos del metabolismo: deficiencia de 6 fosfatasa
Acidosis láctica
12. Experiencia Europea:
Mayor riesgo de hipoglucemias severas con SU que
de Acidosis láctica asociada a metformina. (ALAM).
Metformina ingresó a USA en 1995
Lineamientos de prescripción de metformina
en relación a función renal ( FDA)
“Metformina contraindicada en enfermedad o
disfunción renal (sugerida por creatinina sérica ≥ 1.5
mg/dl en hombres y ≥ 1.4mg/dl en mujeres.)
No deberá ser indicada en pacientes ≥ 80 años
excepto si tienen pruebas de depuración de
creatinina que demuestren función renal normal”
Advertencia: asociado a acidosis láctica
Campbell I.Horm Metab Res 1985
http://www.fda.gov/ohrms/dockets
13. Uso de Metformina en pacientes don DM2 tomando hipoglucemiantes
orales en relación con TFGe. NHNES 2011-2012 USA
Flory JH and Hennessy S. JAMA internal medicine 2015
16. Metformina Fenformina
No metabolizado
Excretado sin
modificar
Efecto/acción
Diferencias farmacológicas entre metformina y fenformina
Inhibición de la oxidación
de glucosa
Mayor liberación de
lactato muscular y
menor oxidación
Metabolismo
Ausente Presente
Derivado hidroxilado
inactivo
Tahani AA et al.BMJ 2007 Oattes LS et al Clin Pharmacol Ther 1987
18. Diabet. Med. 31, 1032–1038 (2014)W. R. Adam1 and R. C. O’Brien
Relación de metformina con PH
y lactato en sangre
19. Incidencia de acidosis láctica asociada a
metformina
~ 1 por 23,000 a 30,000personas-años en pacientes
tratados con metformina 1
1´por 18,000 a 21,000 personas- años en
pacientes con DM2 tratados con otros fármacos
antidiabéticos. 2
20. Objetivos
Medir la incidencia de acidosis láctica fatal y no fatal, y los valores de
lactato en sangre,en pacientes tratados con metformina y en los
tratados con otros fármacos antidiabéticos
Criterios de selección
Estudios prospectivos comparativos y estudios de cohorte en pacientes
con diabetes mellitus tipo 2 de por lo menos un mes de duración,
fueron incluidos si evaluaban Metformina, En monoterapia o en
combinación con otros tratamientos, comparada con placebo u otros
fármacos antidiabéticos
Salpeter SR et al The Cochrane Library 2010
21. Resultados principales
En la revisión los valores individuales de creatinina no estuvieron
disponibles, el 53% de los estudios revisados, no excluyeron
pacientes con valores de creatinina sérica > 1.5mg/dl.
Equivale al uso de metformina en 37,600 pacientes-años en estudios
que incluyeron pacientes con enfermedad crónica renal
Sin desarrollar acidosis lactica
Los datos agrupados de 347 estudios comparativos y de cohortes
Reportaron una incidencia de acidosis láctica de 4.3 casos por
100,000 pacientes-años en el grupo de pacientes tratados con
Metformina y 5.4 casos por 100,000 pacientes años en el grupo
tratado con otros fármacos antidiabéticos
Salpeter SR et al The Cochrane Library 2010
22. Asociación Latino-
Americana de
Diabetes. (ALAD)2013
TFG ≥ 30 a ≤ 45ml/min
Metformina ( dosis máxima de
1000mg). Valoración periódica
Asociación Americana
de Endocrinólogos
Clínicos (AACE) 2011
Asociación Americana
De Diabetes. ADA 2012
NICE ( RU ) 2009
Asociación Canadiense
de diabetes
Revisar la dosis de metformina si Crs >1.7 o
TFGe < 30ml/min/1.73 m
Revisar la dosis de metformina si Crs >1.5 o
TFGe < 45ml/min/1.73 m
Metfomina contraindicada en ERC
estadios 4 (15 a 29ml/min) y
5 ( < 15ml/min
Apoya los criterios de NICE
Debate para valorar uso menos
Restrictivo de metformina en ERC
TFGe 30 a 60ml/min/1.73m dosis
850mg
TFGE 60 a 90 ml/min/1.73m2: 1700mg
23. Inzuchi SE et als JAMA 2014
Propuesta de uso de metformina en ERC
24. Agencia regulatoria de medicamentos y productos de
salud en el Reino Unido
Enero 2015 aprobó:
Uso de metformina en pacientes con moderado deterioro renal,
estado 3ª ( Depuración de creatinina o TFG 45 a 59 ml/min/1.73 m2 en
ausencia de otras condiciones que pueden incrementar el riesgo de
acidosis láctica.
Si la depuración de creatinina o laTFGe disminuye de 45 ml/min
la metformina deberá suspenderse.
25. Conclusiones
Acidosis láctica inducida por metformina es una
condición muy rara
Existen evidencias que el uso de metformina puede ser
menos restringido en la mayor parte de las etapas de la
enfermedad renal crónica
La mayoría de los casos de ALAM coexisten con otras
causas posibles de AL
Seguimiento de situaciones clínicas que produzcan un
deterioro agudo de la función renal
Notas del editor
Chemistry of the biguanides
While many biguanides have been synthesized, only a few exert a glucose-lowering effect. As can be seen in figure 2, the biguanides have a shared basis, originating from two linked guanidines (in blue). The pharmacological differences between the biguanides are determined by differences in their non-polar hydrocycarbon side chains (in red). As a result of these non-polar side chains the biguanides bind to membrane phospholipids and other biological structures.
6
Metformin is first-line therapy in most international guidelines [1,8].
Metformin also has significant benefits over many other therapies: low cost, low risk of hypoglycaemia and lack of weight gain [5],
In large observational studies, metformin is associated with lower rates of cardiovascular disease and lower overall mortality than is seen with other hypoglycemic agents, even if patients have renal impairment [9–11].
Metformin remains a useful therapy even in insulin- treated patients; the benefits include improved glycaemic control, reduced insulin dose and low rates of hypoglycaemia
for a given HbA1c level [13–15].
Chemistry of the biguanides
While many biguanides have been synthesized, only a few exert a glucose-lowering effect. As can be seen in figure 2, the biguanides have a shared basis, originating from two linked guanidines (in blue). The pharmacological differences between the biguanides are determined by differences in their non-polar hydrocycarbon side chains (in red). As a result of these non-polar side chains the biguanides bind to membrane phospholipids and other biological structures.
The initial link between lactic acidosis and metformin was made because metformin is a member of the biguanide class, and the first biguanide, phenformin, was clearly associated
with an increased risk of developing lactic acidosis [17]. Metformin has always come under scrutiny, in our view unfairly, as a potential cause of lactic acidosis and, as a consequence, there are multiple case reports in the literature of lactic acidosis associated with metformin. However, metformin and phenformin differ markedly in their rates of uptake into cells and in their metabolism [18], with phenformin having considerably more potential for toxicity. In contrast to the well-documented benefits of metformin, the risks of developing lactic acidosis are not clear for two main reasons: firstly the problem is extremely rare and, secondly there are multiple causes of lactic acidosis. Indeed, it is questionable whether metformin, when used therapeutically, ever causes lactic acidosis, even in patients with renal failure. Thus, the term metformin-associated lactic acidosis is commonly
used, implying a causation is yet to be established
Metformin is not metabolized in animals or humans and is eliminated intact through renal excretion. The maximal approved total daily dose of metformin for treatment of diabetes mellitus is 2.5 g (35 mg/kg body weight). After oral administration,
metformin is absorbed into the enterocytes through the plasma monoamine transporter (PMAT) and organic cation transporter 3 (OCT3) on the apical membrane and leaves the enterocytes via OCT1 on the basolateral membrane (Figure 1). Metformin is then delivered directly to the liver through the portal vein, and plasma concentrations in the portal vein are between 40 and 70 mM in animals after a therapeutic dose. The uptake of metformin in the liver is through the OCT1/3 on the membrane of hepatocytes,
while metformin is excreted from hepatocytes by the multidrug and toxin extrusion 1 (MATE1) transporter. T.
After hepatic uptake, the systemic plasma concentration of metformin is reduced to 10–40 mM in animals (Wilcock and Bailey, 1994) and in humans. In the kidney, metformin is absorbed from the circulation into renal epithelial cells by OCT2 and excreted into urine by MATE1/2k (Gong et al., 2012).
Proposed Models for the Suppression of Glucose Production by Metformin
Model 1(left): Supra-pharmacologic metformin concentrations suppress glucose production through the
inhibition of complex 1 in mitochondria, which increases AMP levels and subsequently blocks the cAMPPKA
pathway by the inhibition of adenylyl cyclase activity. Elevated AMP levels could also activate AMPK.
Model 2 (middle): Pharmacologic metformin concentrations, found in the portal vein, activate AMPK,
which inhibit gluconeogenic gene expression by phosphorylation of CBP and CRTC2. Model 3 (right):
Pharmacologic metformin concentrations inhibit mitochondrial glycerol 3-phosphate dehydrogenase,
leading to an increase in cytosolic NADH levels, which prevents lactate utilization and decreases gluconeogenesis.
However, NADH is also consumed in gluconeogenesis at the GAPDH enzymatic step.
For example, Miller et al. (2013) used phenformin, not metformin, in most of their studies, noting that this drug, with increased lipid solubility, is a more effective inhibitor of complex 1 of the electron transport chain. For the same reason, phenformin is about 20 times more likely to cause lactic acidosis in man and has been banned for human use in most countries worldwide
FIGURE 1 The relationship between plasma metformin and pH (X) and plasma lactate (O) in 22 patients following an intentional overdose of metformin (and other drugs) (Dell’Aglio et al. [29]). There was a poor correlation between plasma metformin and pH or plasma lactate. Lactic acidosis was only present when plasma metformin levels were > 40 mg/l, and then only in some patients
FIGURE 2 The relationship between blood pH and plasma lactate in 22 patients followinganintentional overdose ofmetformin (and other drugs) (Dell’Aglio et al. [29]). There was a better correlation between plasma lactate and pH (R = 0.95) than plasma metformin and pH (Fig. 1).
Differences in the side-chains of metformin and phenformin may also explain the differences in effects and side-effects of these drugs. As noted, phenformin was eventually banned from medical use because of a very high incidence of (fatal) lactic acidosis. However, lactic acidosis occurs much more frequently with phenformin than with metformin. This difference in the incidence of lactic acidosis between phenformin can be related to their different chemical structure. Firstly, in contrast to metformin, modestly raised phenformin concentrations may reduce peripheral glucose oxidation and enhance peripheral lactate production, leading to lactate accumulation. In line with this, phenformin levels correlate with plasma lactate, whereas metformin levels do not. Secondly, the route of metabolism of phenformin involves a hydroxylation step in the liver. About 10% of the Caucasian population has a genetic polymorphism that affects this step and which leads to a reduced clearance of phenformin, thus increasing the risk for side effects such as lactic acidosis. Finally, the higher lipophilicity of phenformin may lead to its accumulation in the mitochondrion, where it will exert its detrimental effects on lactate turnover.