Clinical Pharmacology for Lialda
Mechanism Of Action
The mechanism of action of mesalamine is not fully understood, but it appears to have a topical anti-inflammatory effect on the colonic epithelial cells. Mucosal production of arachidonic acid metabolites, both through the cyclooxygenase and lipoxygenase pathways, is increased in patients with ulcerative colitis, and it is possible that mesalamine diminishes inflammation by blocking cyclooxygenase and inhibiting prostaglandin production in the colon.
Pharmacokinetics
Absorption
The total absorption of mesalamine from LIALDA 2.4 g or 4.8 g given once daily for 14 days to healthy subjects was found to be approximately 21% to 22% of the administered dose.
Gamma-scintigraphy studies have shown that a single dose of LIALDA 1.2 g (one tablet) passed intact through the upper gastrointestinal tract of fasted healthy subjects. Scintigraphic images showed a trail of radio-labeled tracer in the colon, suggesting that mesalamine had distributed through this region of the gastrointestinal tract.
In a single-dose study, LIALDA 1.2 g, 2.4 g, and 4.8 g were administered in the fasted state to healthy subjects. Plasma concentrations of mesalamine were detectable after 2 hours and reached a maximum by 9-12 hours on average for the doses studied. The pharmacokinetic parameters are highly variable among subjects (Table 4). Mesalamine systemic exposure in terms of area under the plasma concentration-time curve (AUC) was slightly more than dose proportional between 1.2 g and 4.8 g LIALDA. Maximum plasma concentrations (Cmax) of mesalamine increased approximately dose proportionately between 1.2 g and 2.4 g and sub-proportionately between 2.4 g and 4.8 g of LIALDA, with the dose normalized value at 4.8 g representing, on average, 74% of that at 2.4 g based on geometric means.
Table 4: Mean (SD) Pharmacokinetic Parameters for Mesalamine Following Single-Dose Administration of LIALDA Under Fasting Conditions
| Parameter* of Mesalamine |
LIALDA 1.2 g
(N=47) |
LIALDA 2.4 g
(N=48) |
LIALDA 4.8 g
(N=48) |
| AUC0-t (ng•h/mL) |
9039†
(5054) |
20538
(12980) |
41434
(26640) |
| AUC0-∞ (ng•h/mL) |
9578‡
(5214) |
21084
(13185) |
44775§
(30302) |
| Cmax (ng/mL) |
857
(638) |
1595
(1484) |
2154
(1140) |
| Tmax¶ (h) |
9.0#
(4.0-32.1) |
12.0
(4.0-34.1) |
12.0
(4.0-34.0) |
| Tlag ¶ (h) |
2.0#
(0-8.0) |
2.0
(1.0-4.0) |
2.0
(1.0-4.0) |
| T½ (h) (Terminal Phase) |
8.56‡
(6.38) |
7.05Þ
(5.54) |
7.25§
(8.32) |
*Arithmetic mean of parameter values are presented except for Tmax and Tlag.
†N=43, ‡N=27, §N=36, ¶Median (min, max), #N=46, ÞN=33 |
Food Effects
Administration of a single dose of LIALDA 4.8 g with a high-fat meal resulted in further delay in absorption, and plasma concentrations of mesalamine were detectable 4 hours following dosing. However, a high-fat meal increased systemic exposure of mesalamine (mean Cmax: increased 91%; mean AUC: increased 16%) compared to results in the fasted state. LIALDA was administered with food in the controlled clinical trials [see DOSAGE AND ADMINISTRATION].
In a single- and multiple-dose pharmacokinetic study of LIALDA, 2.4 g or 4.8 g was administered once daily with standard meals to 28 healthy subjects per dose group. Plasma concentrations of mesalamine were detectable after 4 hours and were maximal by 8 hours after the single dose. Steady state was achieved generally by 2 days after dosing. Mean AUC at steady state was only modestly greater (1.1- to 1.4-fold) than predictable from single dose pharmacokinetics.
Distribution
Mesalamine is approximately 43% bound to plasma proteins at the concentration of 2.5 mcg/mL.
Elimination
Metabolism
The only major metabolite of mesalamine (5-aminosalicylic acid) is N-acetyl-5-aminosalicylic acid. Its formation is brought about by N-acetyltransferase (NAT) activity in the liver and intestinal mucosa cells, principally by NAT-1.
Excretion
Excretion of mesalamine is mainly via the renal route following metabolism to N-acetyl-5-aminosalicylic acid (acetylation); however, there is also limited excretion of the parent drug in urine. Of the approximately 21% to 22% of the dose absorbed, less than 8% of the dose was excreted unchanged in the urine after 24 hours, compared with greater than 13% for N-acetyl-5-aminosalicylic acid. The mean renal clearance (CLR) in adults ranged from 1.8 L/h to 2.9 L/h following single dose administration and ranged from 5.5 L/h to 6.4 L/h after a multiple dosing for 14 days. The apparent terminal half-lives for mesalamine and its major metabolite after administration of LIALDA 2.4 g and 4.8 g were, on average, 7 to 9 hours and 8 to 12 hours, respectively.
Systemic exposures in adult subjects were inversely correlated with renal function as assessed by estimated creatinine clearance [see Use In Specific Populations].
Specific Populations
Geriatric Patients
In a single-dose pharmacokinetic study of LIALDA, 4.8 g was administered in the fasted state to 71 healthy male and female subjects (28 young (18-35 years); 28 elderly (65-75 years); 15 elderly (>75 years)). Increased age resulted in increased systemic exposure (approximately 2-fold in Cmax) to mesalamine and its metabolite N-acetyl-5-aminosalicylic acid. Increased age resulted in a slower apparent elimination of mesalamine, though there was high between-subject variability.
Table 5: Mean (SD) Pharmacokinetic Parameters for Mesalamine Following Single-Dose Administration of LIALDA 4.8 g under Fasting Conditions to Young and Elderly Subjects
| Parameter of 5-ASA |
Young Subjects (18 to 35 years)
(N=28) |
Elderly Subjects (65 to 75 years)
(N=28) |
Elderly Subjects (75 years and older)
(N=15) |
| AUC0-t (ng•h/mL) |
51570
(23870) |
73001
(42608) |
65820
(25283) |
| AUC0-∞ (ng•h/mL) |
58057*
(22429) |
89612†
40596) |
63067‡
(22531) |
| Cmax (ng/mL) |
2243
(1410) |
4999
(4381) |
4832
(4383) |
| tmax § (h) |
22.0
(5.98-48.0) |
12.5
(4.00-36.0) |
16.0
(4.00-26.0) |
| tlag § (h) |
2(1-6) |
2(1-4) |
2
(2-4) |
| t½ (h), terminal phase |
5.68*
(2.83) |
9.68†
(7.47) |
8.67‡
(5.84) |
| Renal clearance (L/h) |
2.05
(1.33) |
2.04
(1.16) |
2.13
(1.20) |
Arithmetic mean (SD) data are presented, N = Number of subjects; 5-ASA = 5-aminosalicylic acid
*N=15, †N=16, ‡N=13, §Median (min-max) |
Pediatric Patients
In pediatric patients 5 years to 17 years of age diagnosed with ulcerative colitis, systemic exposure of mesalamine, as measured by mean AUCss and Cmax,ss, increased in a dose-proportional manner between 30 and 60 mg/kg/day of LIALDA and increased in a sub-proportional between 60 and 100 mg/kg/day doses. Pharmacokinetic parameters had moderate to high inter-subject variability with CV% ranging from 36% to 52% in pediatric patients.
The overall systemic exposure of mesalamine following oral administration of 4.8 g once daily for 7 days in a limited number of pediatric patients 5 years to 17 years of age (AUC range of 30,556 to 50,388 ng•hr/mL, n=3) was in similar range to that was observed in the healthy adults (AUC of 41,434 ± 26,640 ng•hr/mL, n=48) after single dose administration.
The mean renal clearance (CLR) of mesalamine in pediatric patients (range from approximately 5.0 to 6.5 L/h) seems to be similar to that observed with healthy adult subjects after multiple dose administration.
Drug Interaction Studies
The potential effect of LIALDA (4.8 g given once daily) on the pharmacokinetics of four commonly used antibiotics were evaluated in healthy subjects. The four antibiotics studied and their dosing regimens were as follows: amoxicillin (single 500-mg dose), ciprofloxacin XR (single 500-mg dose), metronidazole (750 mg twice daily for 3.5 days), and sulfamethoxazole/trimethoprim (800 mg/160 mg twice daily for 3.5 days). The change in Cmax and AUC of amoxicillin, ciprofloxacin, and metronidazole when they were co-administered with LIALDA were all 3% or less. There was an increase of 12% in Cmax and an increase of 15% in AUC of sulfamethoxazole when sulfamethoxazole/trimethoprim was coadministered with LIALDA. Coadministration of LIALDA did not result in clinically significant changes in the pharmacokinetics of any of the four antibiotics.
Animal Toxicology And/Or Pharmacology
In animal studies with mesalamine, a 13-week oral toxicity study in mice and 13-week and 52-week oral toxicity studies in rats and cynomolgus monkeys have shown the kidney to be the major target organ of mesalamine toxicity. Oral daily doses of 2400 mg/kg in mice and 1150 mg/kg in rats produced renal lesions including granular and hyaline casts, tubular degeneration, tubular dilation, renal infarct, papillary necrosis, tubular necrosis, and interstitial nephritis. In cynomolgus monkeys, oral daily doses of 250 mg/kg or higher produced nephrosis, papillary edema, and interstitial fibrosis.
Clinical Studies
Adults With Mildly To Moderately Active Ulcerative Colitis
Induction Of Remission
Two similarly designed, randomized, double-blind, placebo-controlled trials (Study 1, NCT00503243 and Study 2, NCT00548574) were conducted in 517 adult patients with mildly to moderately active ulcerative colitis. The study population was primarily Caucasian (80%), had a mean age of 42 years (6% age 65 years or older), and was approximately 50% male. Both studies used LIALDA dosages of 2.4 g and 4.8 g administered once daily for 8 weeks, except in Study 1 the 2.4 g dosage was administered as two divided doses (i.e., 1.2 g twice daily). The primary efficacy endpoint in both trials was to compare the percentage of patients in remission after 8 weeks of treatment for the LIALDA treatment groups versus placebo. Remission was defined as an Ulcerative Colitis Disease Activity Index (UC-DAI) of ≤1, with scores of zero for rectal bleeding and for stool frequency, and a sigmoidoscopy score reduction of 1 point or more from baseline.
In both studies, the LIALDA dosages of 2.4 g and 4.8 g once daily demonstrated superiority over placebo in the primary efficacy endpoint (Table 6). Both LIALDA dosages also provided consistent benefit in secondary efficacy parameters, including clinical improvement, clinical remission, and sigmoidoscopic improvement. Both LIALDA dosages had similar efficacy profiles.
Table 6: Proportion of Adult Patients with Mildly to Moderately Active Ulcerative Colitis in Remission at Week 8 in Two Double-Blind Placebo-Controlled Induction Trials
| Dose |
Study 1
(n=262) n/N (%) |
Study 2
(n=255) n/N (%) |
| LIALDA 2.4 g/day |
30/88 (34) |
34/84 (41) |
| LIALDA 4.8 g/day |
26/89 (29) |
35/85 (41) |
| Placebo |
11/85 (13) |
19/86 (22) |
Maintenance Of Remission
A multicenter, randomized, double-blind, active comparator study (Study 3, NCT00151892) was conducted in a total of 826 adult patients in remission from ulcerative colitis. Patients were randomized in a 1:1 ratio to receive either LIALDA 2.4 g administered once daily or another mesalamine delayed-release product administered as 0.8 g twice daily. The study population had a mean age of 45 years (8% age 65 years or older), were 52% male, and were primarily Caucasian (64%).
Maintenance of remission was assessed using a modified UC-DAI. For this trial, maintenance of remission was based on maintaining endoscopic remission defined as a modified UC-DAI endoscopy subscore of ≤1. An endoscopy subscore of 0 represented normal mucosal appearance with intact vascular pattern and no friability or granulation. For this trial the endoscopy score definition of 1 (mild disease) was modified such that it could include erythema, decreased vascular pattern, and minimal granularity; however, it could not include friability.
The proportion of patients who maintained remission at Month 6 in this study using LIALDA 2.4 g once daily (84%) was similar to the comparator (82%).
Pediatric Patients With Mildly To Moderately Active Ulcerative Colitis Weighing At Least 24 kg
A multicenter, randomized, double-blind, parallel-group study (NCT02093663) was conducted in pediatric patients aged 5 through 17 years with mildly to moderately active ulcerative colitis to determine the safety and effectiveness of LIALDA. The study consisted of two treatment phases, an initial 8-week phase and a 26-week phase. The overall population consisted of 105 patients, of whom 27 patients participated in both the 8-week and 26-week phases.
Each phase included two dosage arms and patients were randomized at the beginning of each phase in a 1:1 ratio, stratified by body weight group. Patients received a low or a high weight-based dosage of LIALDA in four weight groups. Because of the small number of patients in the lowest body weight group (0 in the 8-week phase and 3 in the 26-week phase), the safety and effectiveness of LIALDA in patients weighing less than 24 kg have not been established.
Patients were eligible for the initial 8-week phase if they had mildly to moderately active ulcerative colitis as defined by the UC-DAI score of at least 4 with an endoscopic subscore of 2 or 3.
In the 53 patients enrolled in the initial phase, the mean age and weight of patients was 14 years and 53 kg, the mean (SD) baseline UC-DAI score was 5.8 (1.8), 93% were white, and 59% were male. The primary endpoint was defined by the partial UC-DAI less than or equal to 1 (with rectal bleeding equal to 0, stool frequency less than or equal to 1, and Physician’s Global Assessment [PGA] equal to 0). Of the 26 patients in the recommended LIALDA dosage arm, 65% achieved the primary endpoint after 8 weeks of treatment. During the initial 8-week phase, fewer patients who received the recommended LIALDA dosage were discontinued from the study due to ulcerative colitis (0/26, 0%) compared to patients who received a lower than recommended LIALDA dosage (8/27, 30%).
Patients who met the primary endpoint at 8 weeks were eligible to continue treatment in the 26-week phase. Patients were also eligible to enter the 26-week phase without having participated in the 8-week phase if they had a UC-DAI score of less than or equal to 2 with an endoscopic subscore of 0 or 1 (modified to exclude friability).
There were 87 patients enrolled in the 26-week phase. The mean age and weight of patients were 14 years and 54 kg; 97% were white and 55% were female. Of the 42 patients in the recommended LIALDA dosage arm, 55% achieved the primary endpoint, which was defined the same as in the 8-week phase. In the 26-week phase, the arm with a higher than recommended LIALDA dosage was not more effective and is not recommended [see DOSAGE AND ADMINISTRATION].
Other Endpoints
Clinical remission, defined by a Mayo stool frequency subscore equal to 0 or 1, Mayo rectal bleeding subscore equal to 0, and a Mayo endoscopic subscore equal to 0 or 1 (modified to exclude friability) or 0 on the UC-DAI, was determined for patients with available endoscopic assessment after completion of the 26-week phase. Patients without endoscopic data at week 26 were assumed not to have achieved clinical remission. Of the 42 patients in the recommended LIALDA dosage arm, 36% achieved clinical remission. Clinical remission could not be assessed in the initial 8-week phase because there were too few patients who underwent endoscopy.