OVERDOSAGE
In mice and rats, large intravenous doses of meropenem (2200-4000 mg/kg) have been associated with ataxia, dyspnea, convulsions, and mortalities.
Intentional overdosing of MERREM I.V. is unlikely, although accidental overdosing might occur if large doses are given to patients with reduced renal function. The largest dose of meropenem administered in clinical trials has been 2 g given intravenously every 8 hours. At this dosage, no adverse pharmacological effects or increased safety risks have been observed.
No specific information is available for the treatment of MERREM I.V. overdosage. In the event of an overdose, MERREM I.V. should be discontinued and general supportive treatment given until renal elimination takes place. Meropenem and its metabolite are readily dialyzable and effectively removed by hemodialysis; however, no information is available on the use of hemodialysis to treat overdosage.
CLINICAL STUDIES
INTRA-ABDOMINAL:
One controlled clinical study of complicated intra-abdominal infection was performed in the United States where meropenem was compared to clindamycin/tobramycin. Three controlled clinical studies of complicated intra-abdominal infections were performed in Europe; meropenem was compared to imipenem (two trials) and cefotaxime/metronidazole (one trial).
Using strict evaluability criteria and microbiologic eradication and clinical cures at follow-up which occurred 7 or more days after completion of therapy, the following presumptive microbiologic eradication/clinical cure rates and statistical findings were obtained:
Treatment Arm
|
No. evaluable/
No. enrolled (%)
|
Microbiologic
Eradication Rate
|
Clinical Cure
Rate
|
Outcome
|
meropenem
|
146/516 (28%) |
98/146 (67%) |
101/146 (69%) |
|
imipenem
|
65/220 (30%) |
40/65 (62%) |
42/65 (65%) |
Meropenem
|
|
|
|
|
equivalent
to control
|
cefotaxime/
metronidazole
|
26/85 (30%) |
22/26 (85%) |
22/26 (85%) |
Meropenem
|
|
|
|
|
not equivalent
to control
|
clindamycin/
tobramycin
|
50/212 (24%) |
38/50 (76%) |
38/50 (76%) |
Meropenem
|
|
|
|
|
equivalent
to control
|
|
The finding that meropenem was not statistically equivalent to cefotaxime/metronidazole may have been due to uneven assignment of more seriously ill patients to the meropenem arm. Currently there is no additional information available to further interpret this observation.
BACTERIAL MENINGITIS:
Four hundred forty-six patients (397 pediatric patients >/= 3 months to < 17 years of age) were enrolled in 4 separate clinical trials and randomized to treatment with meropenem (n=225) at a dose of 40 mg/kg q 8 hours or a comparator drug, i.e., cefotaxime (n=187) or ceftriaxone (n=34), at the approved dosing regimens. A comparable number of patients were found to be clinically evaluable (ranging from 61-68%) and with a similar distribution of pathogens isolated on initial CSF culture.
Patients were defined as clinically not cured if any one of the following three criteria were met:
-
At the 5-7 week post-completion of therapy visit, the patient had any one of the following: moderate to severe motor, behavior or development deficits, hearing loss of >60 decibels in one or both ears, or blindness.
-
During therapy the patient's clinical status necessitated the addition of other antibiotics.
-
Either during or post-therapy, the patient developed a large subdural effusion needing surgical drainage, or a cerebral abscess, or a bacteriologic relapse.
Using the definition, the following efficacy rates were obtained, per organism. The values represent the number of patients clinically cured/number of clinically evaluable patients, with the percent cure in parentheses.
MICROORGANISM
|
MERREM I.V.
|
COMPARATOR
|
S. pneumoniae |
17/24 (71) |
19/30 (63) |
H. influenzae (+)
|
8/10 (80) |
6/6 (100) |
H. influenzae (-/NT)
|
44/59 (75) |
44/60 (73) |
N. meningitidis |
30/35 (86) |
35/39 (90) |
|
|
|
TOTAL (including others) |
102/131 (78) |
108/140 (77) |
(+) (beta)-lactamase-producing; (-/NT) non-(beta)-lactamase-producing or not tested
|
|
Sequelae were the most common reason patients were assessed as clinically not cured.
Five patients were found to be bacteriologically not cured, 3 in the comparator group (1 relapse and 2 patients with cerebral abscesses) and 2 in the meropenem group (1 relapse and 1 with continued growth of Pseudomonas aeruginosa).
The adverse events seen were comparable between the two treatment groups both in type and frequency. The meropenem group did have a statistically higher number of patients with transient elevation of liver enzymes. (See ADVERSE REACTIONS.) Rates of seizure activity during therapy were comparable between patients with no CNS abnormalities who received meropenem and those who received comparator agents. In the MERREM I.V. treated group, 12/15 patients with seizures had late onset seizures (defined as occurring on day 3 or later) versus 7/20 in the comparator arm.
With respect to hearing loss, 263 of the 271 evaluable patients had at least one hearing test performed post-therapy. The following table shows the degree of hearing loss between the meropenem-treated patients and the comparator-treated patients.
Degree of Hearing Loss
(in one or both ears)
|
Meropenem
n = 128
|
Comparator
n = 135
|
No loss
|
61%
|
56%
|
20-40 decibels
|
20%
|
24%
|
>40-60 decibels
|
8%
|
7%
|
>60 decibels
|
9%
|
10%
|
|
|