CLINICAL PHARMACOLOGY
Mechanism of Action
Granisetron is a selective 5-hydroxytryptamine3 (5-HT3) receptor antagonist with little or no affinity for other serotonin receptors, including
5-HT1; 5-HT1A; 5-HT1B/C; 5-HT2;
for alpha1-, alpha2- or beta-adrenoreceptors; for dopamine-D2;
or for histamine-H1; benzodiazepine; picrotoxin or opioid receptors.
Serotonin receptors of the 5-HT3 type are located peripherally on
vagal nerve terminals and centrally in the chemoreceptor trigger zone of the
area postrema. During chemotherapy-induced vomiting, mucosal enterochromaffm
cells release serotonin, which stimulates 5-HT3 receptors. This evokes
vagal afferent discharge and may induce vomiting. Animal studies demonstrate
that, in binding to 5-HT3 receptors, granisetron blocks serotonin
stimulation and subsequent vomiting after emetogenic stimuli such as cisplatin.
In the ferret animal model, a single granisetron injection prevented vomiting
due to high-dose cisplatin or arrested vomiting within 5 to 30 seconds.
In most human studies, granisetron has had little effect on blood pressure, heart rate or ECG. No evidence of an effect on plasma prolactin or aldosterone concentrations has been found in other studies.
KYTRIL Injection exhibited no effect on oro-cecal transit time in normal volunteers
given a single intravenous infusion of 50 mcg/kg or 200 mcg/kg. Single and multiple
oral doses slowed colonic transit in normal volunteers.
Pharmacokinetics
Chemotherapy-Induced Nausea and Vomiting
In adult cancer patients undergoing chemotherapy and in volunteers, mean pharmacokinetic
data obtained from an infusion of a single 40 mcg/kg dose of KYTRIL Injection
are shown in Table 3.
Table 3: Pharmacokinetic Parameters in Adult Cancer Patients
Undergoing Chemotherapy and in Volunteers, Following a Single Intravenous 40
mcg/kg Dose of KYTRIL Injection
|
Peak Plasma Concentration (ng/mL) |
Terminal Phase Plasma Half-Life (h) |
Total Clearance (L/h/kg) |
Volume of Distribution (L/kg) |
Cancer Patients |
Mean |
63.8* |
8.95* |
0.38* |
3.07* |
Range |
18.0 to 176 |
0.90 to 31.1 |
0.14 to 1.54 |
0.85 to 10.4 |
Volunteers |
21 to 42 years |
|
|
|
|
Mean |
64.3† |
4.91† |
0.79† |
3.04† |
Range |
11. 2 to 182 |
0.88 to 15.2 |
0.20 to 2.56 |
1.68 to 6.13 |
65 to 81 years |
|
|
|
|
Mean |
57.0† |
7.69† |
0.44† |
3.97† |
Range |
14.6 to 153 |
2.65 to 17.7 |
0.17 to 1.06 |
1.75 to 7.01 |
* 5-minute infusion.
†3-minute infusion.
|
Distribution
Plasma protein binding is approximately 65% and granisetron distributes freely between plasma and red blood cells.
Metabolism
Granisetron metabolism involves N-demethylation and aromatic ring oxidation
followed by conjugation. In vitro liver microsomal studies show that
granisetron's major route of metabolism is inhibited by ketoconazole, suggestive
of metabolism mediated by the cytochrome P-450 3 A subfamily. Animal studies
suggest that some of the metabolites may also have 5-HT3 receptor
antagonist activity.
Elimination
Clearance is predominantly by hepatic metabolism. In normal volunteers, approximately 12% of the administered dose is eliminated unchanged in the urine in 48 hours. The remainder of the dose is excreted as metabolites, 49% in the urine, and 34% in the feces.
Subpopulations
Gender
There was high inter- and intra-subject variability noted in these studies. No difference in mean AUC was found between males and females, although males had a higher Cmax generally.
Elderly
The ranges of the pharmacokinetic parameters in elderly volunteers (mean age
71 years), given a single 40 mcg/kg intravenous dose of KYTRIL Injection, were
generally similar to those in younger healthy volunteers; mean values were lower
for clearance and longer for half-life in the elderly patients (see Table
3).
Pediatric Patients
A pharmacokinetic study in pediatric cancer patients (2 to 16 years of age),
given a single 40 mcg/kg intravenous dose of KYTRIL Injection, showed that volume
of distribution and total clearance increased with age. No relationship with
age was observed for peak plasma concentration or terminal phase plasma half-life.
When volume of distribution and total clearance are adjusted for body weight,
the pharmacokinetics of granisetron are similar in pediatric and adult cancer
patients.
Renal Failure Patients
Total clearance of granisetron was not affected in patients with severe renal
failure who received a single 40 mcg/kg intravenous dose of KYTRIL Injection.
Hepatically Impaired Patients
A pharmacokinetic study in patients with hepatic impairment due to neoplastic liver involvement showed that total clearance was approximately halved compared to patients without hepatic impairment. Given the wide variability in pharmacokinetic parameters noted in patients, dosage adjustment in patients with hepatic functional impairment is not necessary.
Postoperative Nausea and Vomiting
In adult patients (age range, 18 to 64 years) recovering from elective surgery and receiving general balanced anesthesia, mean pharmacokinetic data obtained from a single 1 mg dose of KYTRIL Injection administered intravenously over 30 seconds are shown in Table 4.
Table 4: Pharmacokinetic Parameters in 16 Adult Surgical
Patients Following a Single Intravenous 1 mg Dose of KYTRIL Injection
|
Terminal Phase Plasma Half-Life (h) |
Total Clearance
(L/h/kg) |
Volume of Distribution
(L/kg) |
Mean |
8.63 |
0.28 |
2.42 |
Range |
1.77 to 17.73 |
0.07 to 0.71 |
0.71 to 4.13 |
The pharmacokinetics of granisetron in patients undergoing surgery were similar to those seen in cancer patients undergoing chemotherapy.
Clinical Studies
Chemotherapy-Induced Nausea and Vomiting
Single-Day Chemotherapy
Cisplatin-Based Chemotherapy
In a double-blind, placebo-controlled study in 28 cancer patients, KYTRIL Injection,
administered as a single intravenous infusion of 40 mcg/kg, was significantly
more effective than placebo in preventing nausea and vomiting induced by cisplatin
chemotherapy (see Table 5).
Table 5: Prevention of Chemotherapy-Induced Nausea and Vomiting
— Single-Day Cisplatin Therapy1
|
KYTRIL Injection |
Placebo |
P-Value |
Number of Patients |
14 |
14 |
|
Response Over 24 Hours |
|
Complete Response2 |
93% |
7% |
< 0.001 |
No Vomiting |
93% |
14% |
< 0.001 |
No More Than Mild Nausea |
93% |
7% |
< 0.001 |
1 Cisplatin administration began within 10 minutes
of KYTRIL Injection infusion and continued for 1.5 to 3.0 hours. Mean cisplatin
dose was 86 mg/m2 in the KYTRIL Injection group and 80 mg/m2
in the placebo group.
2 No vomiting and no moderate or severe nausea. |
KYTRIL Injection was also evaluated in a randomized dose response study of
cancer patients receiving cisplatin ≥ 75 mg/m2. Additional chemotherapeutic
agents included: anthracyclines, carboplatin, cytostatic antibiotics, folic
acid derivatives, methylhydrazine, nitrogen mustard analogs, podophyllotoxin
derivatives, pyrimidine analogs, and vinca alkaloids. KYTRIL Injection doses
of 10 and 40 mcg/kg were superior to 2 mcg/kg in preventing cisplatin-induced
nausea and vomiting, but 40 mcg/kg was not significantly superior to 10 mcg/kg
(see Table 6).
Table 6 Prevention of Chemotherapy-Induced Nausea and Vomiting
— Single-Day High-Dose Cisplatin Therapy1
|
KYTRIL Injection (mcg/kg) |
P-Value (vs. 2 mcg/kg) |
2 |
10 |
40 |
10 |
40 |
Number of Patients |
52 |
52 |
53 |
|
|
Response Over 24 Hours |
|
Complete Response2 |
31% |
62% |
68% |
< 0.002 |
< 0.002 |
No Vomiting |
38% |
65% |
74% |
< 0.002 |
< 0.002 |
No More Than Mild Nausea |
58% |
75% |
79% |
NS |
0.007 |
1 Cisplatin administration began within 10 minutes
of KYTRIL Injection infusion and continued for 2.6 hours (mean). Mean cisplatin
doses were 96 to 99 mg/m2.
2 No vomiting and no moderate or severe nausea. |
KYTRIL Injection was also evaluated in a double-blind, randomized dose response
study of 353 patients stratified for high ( ≥ 80 to 120 mg/m2) or
low (50 to 79 mg/m2) cisplatin dose. Response rates of patients for
both cisplatin strata are given in Table 7.
Table 7: Prevention of Chemotherapy-Induced Nausea and Vomiting
— Single-Day High-Dose and Low-Dose Cisplatin Therapy1
|
KYTRIL Injection (mcg/kg) |
P-Value (vs. 5 mcg/kg) |
|
5 |
10 |
20 |
40 |
10 |
20 |
40 |
High-Dose Cisplatin |
Number of Patients |
40 |
49 |
48 |
47 |
|
|
|
Response Over 24 Hours |
Complete Response2 |
18% |
41% |
40% |
47% |
0.018 |
0.025 |
0.004 |
No Vomiting |
28% |
47% |
44% |
53% |
NS |
NS |
0.016 |
No Nausea |
15% |
35% |
38% |
43% |
0.036 |
0.019 |
0.005 |
Low-Dose Cisplatin |
Number of Patients |
42 |
41 |
40 |
46 |
|
|
|
Response Over 24 Hours |
Complete Response2 |
29% |
56% |
58% |
41% |
0.012 |
0.009 |
NS |
No Vomiting |
36% |
63% |
65% |
43% |
0.012 |
0.008 |
NS |
No Nausea |
29% |
56% |
38% |
33% |
0.012 |
NS |
NS |
1 Cisplatin administration began within 10 minutes
of KYTRIL Injection infusion and continued for 2 hours (mean). Mean cisplatin
doses were 64 and 98 mg/m2 for low and high strata.
2 No vomiting and no use of rescue antiemetic. |
For both the low and high cisplatin strata, the 10, 20, and 40 mcg/kg doses
were more effective than the 5 mcg/kg dose in preventing nausea and vomiting
within 24 hours of chemotherapy administration. The 10 mcg/kg dose was at least
as effective as the higher doses.
Moderately Emetogenic Chemotherapy
KYTRIL Injection, 40 mcg/kg, was compared with the combination of chlorpromazine
(50 to 200 mg/24 hours) and dexamethasone (12 mg) in patients treated with moderately
emetogenic chemotherapy, including primarily carboplatin > 300 mg/m2,
cisplatin 20 to 50 mg/m2 and cyclophosphamide > 600 mg/m2.
KYTRIL Injection was superior to the chlorpromazine regimen in preventing nausea
and vomiting (see Table 8).
Table 8: Prevention of Chemotherapy-Induced Nausea and Vomiting—Single-Day
Moderately Emetogenic Chemotherapy
|
KYTRIL Injection |
Chlorpromazine1 |
P-Value |
Number of Patients |
133 |
133 |
|
Response Over 24 Hours |
Complete Response2 |
68% |
47% |
< 0.001 |
No Vomiting |
73% |
53% |
< 0.001 |
No More Than Mild Nausea |
77% |
59% |
< 0.001 |
1 Patients also received dexamethasone, 12 mg.
2 No vomiting and no moderate or severe nausea.
|
In other studies of moderately emetogenic chemotherapy, no significant difference
in efficacy was found between KYTRIL doses of 40 mcg/kg and 160 mcg/kg.
Repeat-Cycle Chemotherapy
In an uncontrolled trial, 512 cancer patients received KYTRIL Injection, 40
mcg/kg, prophylactically, for two cycles of chemotherapy, 224 patients received
it for at least four cycles, and 108 patients received it for at least six cycles.
KYTRIL Injection efficacy remained relatively constant over the first six repeat
cycles, with complete response rates (no vomiting and no moderate or severe
nausea in 24 hours) of 60% to 69%. No patients were studied for more than 15
cycles.
Pediatric Studies
A randomized double-blind study evaluated the 24-hour response of 80 pediatric
cancer patients (age 2 to 16 years) to KYTRIL Injection 10, 20 or 40 mcg/kg.
Patients were treated with cisplatin ≥ 60 mg/m2, cytarabine ≥ 3
g/m2, cyclophosphamide ≥ 1 g/m2 or nitrogen mustard
≥ 6 mg/m2 (see Table 9).
Table 9: Prevention of Chemotherapy-Induced Nausea and Vomiting
in Pediatric Patients
|
KYTRIL Injection Dose (mcg/kg) |
10 |
20 |
40 |
Number of Patients |
29 |
26 |
25 |
Median Number of Vomiting Episodes |
2 |
3 |
1 |
Complete Response Over 24 Hours1 |
21% |
31% |
32% |
1 No vomiting and no moderate or severe nausea.
|
A second pediatric study compared KYTRIL Injection 20 mcg/kg to chlorpromazine
plus dexamethasone in 88 patients treated with ifosfamide ≥ 3 g/m2/day
for two or three days. KYTRIL Injection was administered on each day of ifosfamide
treatment. At 24 hours, 22% of KYTRIL Injection patients achieved complete response
(no vomiting and no moderate or severe nausea in 24 hours) compared with 10%
on the chlorpromazine regimen. The median number of vomiting episodes with KYTRIL
Injection was 1.5; with chlorpromazine it was 7.0.
Postoperative Nausea and Vomiting
Prevention of Postoperative Nausea and Vomiting
The efficacy of KYTRIL Injection for prevention of postoperative nausea and
vomiting was evaluated in 868 patients, of which 833 were women, 35 men, 484
Caucasians, 348 Asians, 18 Blacks, 18 Other, with 61 patients 65 years or older.
KYTRIL was evaluated in two randomized, double-blind, placebo-controlled studies
in patients who underwent elective gynecological surgery or cholecystectomy
and received general anesthesia. Patients received a single intravenous dose
of KYTRIL Injection (0.1 mg, 1 mg or 3 mg) or placebo either 5 minutes before
induction of anesthesia or immediately before reversal of anesthesia. The primary
endpoint was the proportion of patients with no vomiting for 24 hours after
surgery. Episodes of nausea and vomiting and use of rescue antiemetic therapy
were recorded for 24 hours after surgery. In both studies, KYTRIL Injection
(1 mg) was more effective than placebo in preventing postoperative nausea and
vomiting (see Table 10). No additional benefit was seen in patients who
received the 3 mg dose.
Table 10: Prevention of Postoperative Nausea and Vomiting
in Adult Patients
Study and Efficacy Endpoint |
Placebo |
KYTRIL
0.1 mg |
KYTRIL
1 mg |
KYTRIL
3 mg |
Study 1 Number of Patients |
133 |
132 |
134 |
128 |
No Vomiting 0 to 24 hours |
34% |
45% |
63%** |
62%** |
No Nausea 0 to 24 hours |
22% |
28% |
50%** |
42%** |
No Nausea or Vomiting 0 to 24 hours |
18% |
27% |
49%** |
42%** |
No Use of Rescue Antiemetic Therapy 0 to 24 hours |
60% |
67% |
75%* |
77%* |
Study 2 Number of Patients |
111 |
- |
110 |
114 |
No Vomiting 0 to 24 hours |
56% |
- |
77%** |
75%* |
No Nausea 0 to 24 hours |
37% |
- |
59%** |
56%* |
*P < 0.05
**P < 0.001 versus placebo
Note: No Vomiting = no vomiting and no use of rescue antiemetic therapy;
No Nausea = no nausea and no use of rescue antiemetic therapy |
Gender/Race
There were too few male and Black patients to adequately assess differences in effect in either population.
Treatment of Postoperative Nausea and Vomiting
The efficacy of KYTRIL Injection for treatment of postoperative nausea and
vomiting was evaluated in 844 patients, of which 731 were women, 113 men, 777
Caucasians, 6 Asians, 41 Blacks, 20 Other, with 107 patients 65 years or older.
KYTRIL Injection was evaluated in two randomized, double-blind, placebo-controlled
studies of adult surgical patients who received general anesthesia with no prophylactic
antiemetic agent, and who experienced nausea or vomiting within 4 hours postoperatively.
Patients received a single intravenous dose of KYTRIL Injection (0.1 mg, 1 mg
or 3 mg) or placebo after experiencing postoperative nausea or vomiting. Episodes
of nausea and vomiting and use of rescue antiemetic therapy were recorded for
24 hours after administration of study medication. KYTRIL Injection was more
effective than placebo in treating postoperative nausea and vomiting (see Table
11). No additional benefit was seen in patients who received the 3 mg dose.
Table 11: Treatment of Postoperative Nausea and Vomiting
in Adult Patients
Study and Efficacy Endpoint |
Placebo |
KYTRIL
0.1 mg |
KYTRIL
1 mg |
KYTRIL
3 mg |
Study 3 Number of Patients |
133 |
128 |
133 |
125 |
No Vomiting |
0 to 6 hours |
26% |
53%*** |
58%*** |
60%*** |
0 to 24 hours |
20% |
38%*** |
46%*** |
49o/0*** |
No Nausea |
|
0 to 6 hours |
17% |
40%*** |
41%*** |
42%*** |
0 to 24 hours |
13% |
27%** |
30%** |
37%*** |
No Use of Rescue Antiemetic Therapy |
0 to 6 hours |
- |
- |
- |
- |
0 to 24 hours |
33% |
51%** |
61%*** |
61%*** |
Study 4 Number of Patients (All Patients) |
162 |
163 |
- |
- |
No Vomiting |
0 to 6 hours |
20% |
32%* |
- |
- |
0 to 24 hours |
14% |
23%* |
- |
- |
No Nausea |
0 to 6 hours |
13% |
18% |
- |
- |
0 to 24 hours |
9% |
14% |
- |
- |
No Nausea or Vomiting 0 to 6 hours |
13% |
18% |
- |
- |
0 to 24 hours |
9% |
14% |
- |
- |
No Use of Rescue Antiemetic |
Therapy |
|
0 to 6 hours |
|
|
|
|
0 to 24 hours |
24% |
34%* |
- |
- |
Number of Patients (Treated for Vomiting)1 |
86 |
103 |
- |
- |
No Vomiting |
|
0 to 6 hours |
21% |
27% |
- |
- |
0 to 24 hours |
14% |
20% |
- |
- |
*P < 0.05 **P < 0.01
***P < 0.001 versus placebo
1 Protocol Specified Analysis: Patients who had vomiting prior
to treatment
Note: No vomiting = no vomiting and no use of rescue antiemetic therapy;
No nausea = no nausea and no use of rescue antiemetic therapy |
Gender/Race
There were too few male and Black patients to adequately assess differences in effect in either population.