Combination of two antihyperglycaemic medicinal products with complementary and distinct mechanisms of action which improve glycaemic control in patients with type 2 diabetes mellitus: alogliptin, a dipeptidyl-peptidase-4 (DPP-4) inhibitor, and metformin, a member of the biguanide class.
Alogliptin is a potent and highly selective inhibitor of DPP-4, >10,000-fold more selective for DPP-4 than other related enzymes including DPP-8 and DPP-9. DPP-4 is the principal enzyme involved in the rapid degradation of the incretin hormones, glucagon-like peptide-1 (GLP-1) and GIP (glucose-dependent insulinotropic polypeptide), which are released by the intestine and levels are increased in response to a meal. GLP-1 and GIP increases insulin biosynthesis and secretion from pancreatic beta cells, while GLP-1 also inhibits glucagon secretion and hepatic glucose production. Alogliptin therefore improves glycaemic control via a glucose-dependent mechanism, whereby insulin release is enhanced and glucagon levels are suppressed when glucose levels are high.
Metformin is a biguanide with antihyperglycaemic effects, lowering both basal and postprandial plasma glucose. It does not stimulate insulin secretion and, therefore, does not produce hypoglycaemia
Metformin may act via 3 mechanisms:
Metformin stimulates intracellular glycogen synthesis by acting on glycogen synthase. It also increases the transport capacity of specific types of membrane glucose transporters (GLUT-1 and GLUT-4).
In humans, independently of its action on glycaemia, metformin has favourable effects on lipid metabolism. This has been shown at therapeutic doses in controlled, medium-term or long-term clinical studies; metformin reduces total cholesterol, LDL cholesterol and triglyceride levels.
The results of bioequivalence studies in healthy subjects demonstrated that alogliptin/metformin film-coated tablets are bioequivalent to the corresponding doses of alogliptin and metformin co-administered as separate tablets.
Co-administration of 100 mg alogliptin once daily and 1,000 mg metformin hydrochloride twice daily for 6 days in healthy subjects had no clinically relevant effects on the pharmacokinetics of alogliptin or metformin.
Administration of alogliptin/metformin with food resulted in no change in total exposure (AUC) to alogliptin or metformin. However, mean peak plasma concentrations of alogliptin and metformin were decreased by 13% and 28% when alogliptin/metformin was administered with food, respectively. There was no change in the time to peak plasma concentration (Tmax) for alogliptin, but there was a delayed Tmax for metformin of 1.5 hours. These changes are not likely to be clinically significant (see below).
Alogliptin/metformin should be taken twice daily because of the pharmacokinetics of its metformin component. It should also be taken with meals to reduce the gastrointestinal undesirable effects associated with metformin.
The pharmacokinetics of alogliptin/metformin in children and adolescents <18 years old has not been established. No data are available.
The following section outlines the pharmacokinetic properties of the individual components of alogliptin/metformin as reported in their respective Summary of Product Characteristics.
The pharmacokinetics of alogliptin has been shown to be similar in healthy subjects and in patients with type 2 diabetes mellitus.
The absolute bioavailability of alogliptin is approximately 100%.
Administration with a high-fat meal resulted in no change in total and peak exposure to alogliptin. Alogliptin may, therefore, be administered with or without food.
After administration of single oral doses of up to 800 mg in healthy subjects, alogliptin was rapidly absorbed with peak plasma concentrations occurring 1 to 2 hours (median Tmax) after dosing.
No clinically relevant accumulation after multiple dosing was observed in either healthy subjects or in patients with type 2 diabetes mellitus.
Total and peak exposure to alogliptin increased proportionately across single doses of 6.25 mg up to 100 mg alogliptin (covering the therapeutic dose range). The inter-subject coefficient of variation for alogliptin AUC was small (17%).
Following a single intravenous dose of 12.5 mg alogliptin to healthy subjects, the volume of distribution during the terminal phase was 417 L indicating that the active substance is well distributed into tissues.
Alogliptin is 20-30% bound to plasma proteins.
Alogliptin does not undergo extensive metabolism, 60-70% of the dose is excreted as unchanged active substance in the urine.
Two minor metabolites were detected following administration of an oral dose of [14C] alogliptin, N-demethylated alogliptin, M-I (<1% of the parent compound), and N-acetylated alogliptin, M-II (<6% of the parent compound). M-I is an active metabolite and is a highly selective inhibitor of DPP-4 similar to alogliptin; M-II does not display any inhibitory activity towards DPP-4 or other DPP-related enzymes. In vitro data indicate that CYP2D6 and CYP3A4 contribute to the limited metabolism of alogliptin.
In vitro studies indicate that alogliptin does not induce CYP1A2, CYP2B6 and CYP2C9 and does not inhibit CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 or CYP3A4 at concentrations achieved with the recommended dose of 25 mg alogliptin. Studies in vitro have shown alogliptin to be a mild inducer of CYP3A4, but alogliptin has not been shown to induce CYP3A4 in studies in vivo.
In studies in vitro, alogliptin was not an inhibitor of the following renal transporters; OAT1, OAT3 and OCT2.
Alogliptin exists predominantly as the (R)-enantiomer (>99%) and undergoes little or no chiral conversion in vivo to the (S)-enantiomer. The (S)-enantiomer is not detectable at therapeutic doses.
Alogliptin was eliminated with a mean terminal half-life (T1/2) of approximately 21 hours.
Following administration of an oral dose of [14C] alogliptin, 76% of total radioactivity was eliminated in the urine and 13% was recovered in the faeces.
The average renal clearance of alogliptin (170 mL/min) was greater than the average estimated glomerular filtration rate (approx. 120 mL/min), suggesting some active renal excretion.
Total exposure (AUC) to alogliptin following administration of a single dose was similar to exposure during one dose interval (AUC) after 6 days of once daily dosing. This indicates no time-dependency in the kinetics of alogliptin after multiple dosing.
A single dose of 50 mg alogliptin was administered to 4 groups of patients with varying degrees of renal impairment (CrCl using the Cockcroft-Gault formula): mild (CrCl = >50 to ≤80 mL/min), moderate (CrCl = ≥30 to ≤50 mL/min), severe (CrCl = <30 mL/min) and end-stage renal disease on haemodialysis.
An approximate 1.7-fold increase in AUC for alogliptin was observed in patients with mild renal impairment. However, as the distribution of AUC values for alogliptin in these patients was within the same range as control subjects, no dose adjustment of alogliptin for patients with mild renal impairment is necessary.
In patients with moderate or severe renal impairment, or end-stage renal disease on haemodialysis, an increase in systemic exposure to alogliptin of approximately 2- and 4-fold was observed, respectively. (Patients with end-stage renal disease underwent haemodialysis immediately after alogliptin dosing. Based on mean dialysate concentrations, approximately 7% of the active substance was removed during a 3-hour haemodialysis session.) Therefore, in order to maintain systemic exposures to alogliptin that are similar to those observed in patients with normal renal function, lower doses of alogliptin should be used in patients with moderate or severe renal impairment, or end-stage renal disease requiring dialysis.
Total exposure to alogliptin was approximately 10% lower and peak exposure was approximately 8% lower in patients with moderate hepatic impairment compared to control subjects. The magnitude of these reductions was not considered to be clinically relevant. Therefore, no dose adjustment of alogliptin is necessary for patients with mild to moderate hepatic impairment (Child-Pugh scores of 5 to 9). Alogliptin has not been studied in patients with severe hepatic impairment (Child-Pugh score >9).
Age (65-81 years old), gender, race (white, black and Asian) and body weight did not have any clinically relevant effect on the pharmacokinetics of alogliptin. No dose adjustment is necessary.
The pharmacokinetics of alogliptin in children and adolescents <18 years old has not been established. No data are available.
After an oral dose of metformin, the maximum plasma concentration (Cmax) is reached in approximately 2.5 hours (Tmax). Absolute bioavailability of a 500 mg or 850 mg metformin hydrochloride tablet is approximately 50-60% in healthy subjects. After an oral dose, the non-absorbed fraction recovered in faeces was 20-30%.
After oral administration, metformin absorption is saturable and incomplete. It is assumed that the pharmacokinetics of metformin absorption is non-linear.
At the recommended metformin doses and dosing schedules, steady-state plasma concentrations of metformin are reached within 24 to 48 hours and are generally less than 1 microgram/mL. In controlled clinical studies, maximum metformin plasma levels (Cmax) did not exceed 4 microgram/mL even at maximum doses.
Food slightly delays and decreases the extent of the absorption of metformin. Following oral administration of an 850 mg metformin hydrochloride tablet, the peak plasma concentration was 40% lower, AUC was decreased by 25% and the time to peak plasma concentration (Tmax) was prolonged by 35 minutes. The clinical relevance of these findings is unknown.
Plasma protein binding is negligible. Metformin partitions into erythrocytes. The blood peak is lower than the plasma peak and appears at approximately the same time. The red blood cells most likely represent a secondary compartment of distribution. The mean volume of distribution (Vd) ranged between 63-276 L.
Metformin is excreted unchanged in the urine. No metabolites have been identified in humans.
Renal clearance of metformin is >400 mL/min indicating that metformin is eliminated by glomerular filtration and tubular secretion. Following an oral dose, the apparent terminal elimination half-life is approximately 6.5 hours.
When renal function is impaired, renal clearance is decreased in proportion to that of creatinine and, thus, the elimination half-life is prolonged leading to increased levels of metformin in the plasma.
Due to its metformin component, alogliptin/metformin should not be used in patients with severe renal impairment, or end-stage renal disease requiring dialysis.
Alogliptin/metformin should not be used in patients with hepatic impairment.
Concomitant treatment with alogliptin and metformin did not produce new toxicities and no effects on the toxicokinetics of either compound were observed.
In rats no treatment-related foetal abnormalities occurred following concomitant administration at exposure margins of approximately 28- to 29-fold for alogliptin and 2- to 2.5-fold for metformin at the maximum recommended human dose of 25 mg/day and 2,000 mg/day, respectively. The combination revealed teratogenic potential in small numbers of foetuses (microphthalmia, small eye bulge and cleft palate) at higher doses of metformin (exposure margins of approximately 20-fold and 5- to 6-fold the maximum recommended human dose for alogliptin and metformin, respectively).
The following data are findings from studies performed with alogliptin or metformin individually.
Nonclinical data reveal no special hazard for humans based on conventional studies of safety pharmacology and toxicology.
The no-observed-adverse-effect level (NOAEL) in the repeated dose toxicity studies in rats and dogs up to 26- and 39-weeks in duration, respectively, produced exposure margins that were approximately 147- and 227-fold, respectively, the exposure in humans at the recommended total daily dose of 25 mg alogliptin.
Alogliptin was not genotoxic in a standard battery of in vitro and in vivo genotoxicity studies.
Alogliptin was not carcinogenic in 2-year carcinogenicity studies conducted in rats and mice. Minimal to mild simple transitional cell hyperplasia was seen in the urinary bladder of male rats at the lowest dose used (27 times the human exposure) without establishment of a clear NOEL (no observed effect level).
No adverse effects of alogliptin were observed upon fertility, reproductive performance, or early embryonic development in rats up to a systemic exposure far above the human exposure at the recommended dose. Although fertility was not affected, a slight, statistical increase in the number of abnormal sperm was observed in males at an exposure far above the human exposure at the recommended dose.
Placental transfer of alogliptin occurs in rats.
Alogliptin was not teratogenic in rats or rabbits with a systemic exposure at the NOAELs far above the human exposure at the recommended dose. Higher doses of alogliptin were not teratogenic but resulted in maternal toxicity, and were associated with delayed and/or lack of ossification of bones and decreased foetal body weights.
In a pre- and postnatal development study in rats, exposures far above the human exposure at the recommended dose did not harm the developing embryo or affect offspring growth and development.
Higher doses of alogliptin decreased offspring body weight and exerted some developmental effects considered secondary to the low body weight.
Studies in lactating rats indicate that alogliptin is excreted in milk.
No alogliptin-related effects were observed in juvenile rats following repeat-dose administration for 4 and 8 weeks.
Preclinical data for metformin reveal no special hazard for humans based on conventional studies of safety pharmacology, repeated dose toxicity, genotoxicity, carcinogenic potential, and toxicity to reproduction.
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