3) Diabetes and Multiple Sclerosis Patients Share Common Autoantigens “Thus autoimmunity in diabetes and MS targets a similar set of self-proteins, …
For Your InPHARMation
March 2001
Daniele N Doyle, Ambulatory Care Pharmacist
The Chief, Department of Pharmacy has approved this newsletter for BAMC-
wide distribution
TOPICS INCLUDED IN THIS NEWSLETTER:
1 Fatal Arrhythmia Caused by Lidocaine in Patients with Hyperkalemia
2 More Problems with Herbals–Ginseng and Vaginal Bleeding
3 Diabetes and Multiple Sclerosis Patients Share Common Autoantigens
4 Drug Interaction–Miconazole and Warfarin
5 Linezolid Zyvox Adverse Effect–Myelosuppression
FATAL ARRHYTHMIA CAUSED BY LIDOCAINE IN PATIENTS WITH HYPERKALEMIA
___________________________________________________________
An article published in the Annals of Emergency Medicine present a fairly
concise discussion of the cardiac effects of hyperkalemia and how it can
potentiate the effects of lidocaine administered in emergency settings
The article presents the cases of two patients who died after receiving
bolus injections of lidocaine during emergency procedures to control their
wide-complex tachycardia It was later discovered that they had
hyperkalemia 94mEq/l and 78mEq/l,
respectively
Because high potassium levles potentiate the sodium channel blocking effect
of lidocaine, in hyperkalemic patients lidocaine produces severe depression
of conduction and asystole, often unresponsive to rescue attempts
Since lidocaine is frequently used to treat wide-complex tachycardias, the
authors of the article point out the necessity of checking potassium levels
whenever possible prior to administering the drug
McLean SA, Paul ID, Spector PS Lidocaine-induced conduction disturbance in
patients with systemic hyperkalemia Ann Emerg Med 2000;36;615-18
MORE PROBLEMS WITH HERBALS–GINSENG AND VAGINAL BLEEDING
________________________________________________________
There have been recent reports of adverse effects associated with ginseng,
a very popular herbal supplement touted for its energy and memory enhancing
effects
Ginseng has been reported to cause vaginal bleeding due to estrogenic
effects ascribed to the agent Several cases of irregular bleeding between
menstrual cycles metrorrhagia have been reported with the use of this
supplement Use of ginseng might be a helpful item to tell your healthcare
provider
Reference: Palop-Larrea V Metrorrhagia and
ginseng [letter] Ann
Pharmacother 2000;34:1347-8
DIABETES AND MULTIPLE SCLEROSIS PATIENTS SHARE COMMON AUTOANTIGENS
___________________________________________________________
Autoreactive T cells from both diabetic patients and multiple Sclerosis
MS patients target autoantigens in islet cells and the central nervous
system, according to a report in the February 15th Journal of Immunology
As the authors point out, what usually protects diabetics from MS, and
MS patients from diabetescould have therapeutic ramifications
Dr H-Michael Dosch from The Hospital for Sick Children in Toronto,
Ontario, Canada and colleagues analyzed T-cell autoreactivity in 38
patients with stable or relapsing MS, 54 newly diagnosed children with
diabetes and 105 of their first-degree relatives and 34 healthy controls
Besides recognizing myelin basic protein epitopes, T-cells from MS patients
frequently targeted self-antigens associated with autoimmune diabetes, the
authors report, a phenomenon rarely shown by T-cells from healthy controls
Similarly, T-cells from about two-thirds of diabetes patients and their
first-degree relatives at high risk of developing diabetes
showed
proliferative responses to at least one MS-associated antigen, the report
indicates Low-risk relatives were less likely to have such autoreactive T-
cells
Thus autoimmunity in diabetes and MS targets a similar set of self-
proteins, with neither disease nor tissue selectivity, although epitopes
and T-cell specificities appear to differ, the researchers note
By injecting pertussis toxoid into nonobese diabetic mice, the
investigators created an age-dependent autoimmune encephalitis reminiscent
of primary progressive and relapsing-remitting MS This provides a new MS
model to identify factors that determine alternative disease outcomes in
hosts with similar autoreactive T-cell repertoires, the authors write
Our work implies that there is a lengthy, clinically silent pre-MS phase
analogous to prediabetes, Dr Dosch told Reuters Health Thats good
news: there is strong consensus that we will stop diabetes within a
reasonable time frame through intervention therapies that are targeted to
early prediabetes We hope and have some reason that the same will turn
out to be true for MS, where treatments are rather ineffective
We are preparing for a major, multi-center initiative with
several US
centers to seek out evidence for pre-MS, Dr Dosch said
J Immunol 2001;166:2831-2841
DRUG INTERACTION–MICONAZOLE AND WARFARIN
_________________________________________
The US Food and Drug Administration on Monday warned women taking warfarin
to consult their physicians before using Monistat or other vaginal yeast-
fighting medications that contain miconazole
The FDA said it had asked makers of creams and suppositories containing
miconazole to include a
warning on the products packaging about the possible interaction
Regulators took action after receiving two reports of abnormal blood-
clotting test results in women using both warfarin and a miconazole
product The FDA said in a statement that one of the women developed
bruises, bleeding gums and a nosebleed
Physicians and patients should be aware that patients who need to use both
products simultaneously should be appropriately monitored, the FDA said
LINEZOLID ZYVOX ADVERSE EFFECT–MYELOSUPPRESSION
__________________________________________________
Pharmacia Corporation is warning physicians that some patients taking its
anti-infective drug Zyvox
linezolid may be at increased risk for
myelosuppression
In a Dear Health Care Provider letter issued on Tuesday, the company has
advised physicians to perform weekly complete blood clots in patients
taking the drug in either tablet, injection or oral suspension forms
According to Pharmacia, the warning was based on reports of spontaneous
myelosuppression that it and the FDA received The company noted that it
will update the Adverse Reactions section of Zyvoxs labeling to include
the new information Pharmacia said that patients who are particularly at
risk for myelosuppression are those who have taken Zyvox for more than 2
weeks and those with pre-existing myelosuppression Also at increased risk
may be patients receiving concomitant medications that cause bone marrow
suppression and patients with chronic infection who have received previous
or concomitant antibiotic therapy
The myelosuppressive disorders to which Zyvox has been linked include
anemia, leukopenia, pancytopenia and thrombocytopenia, and they have been
added to the Adverse Reactions section of the Zyvox prescribing
information
These events have been chosen for inclusion due to either their
seriousness, frequency of
reporting, possible causal connection to Zyvox or
a combination of these factors, part of the amended Adverse Reactions
section now reads Because they are reported voluntarily from a population
of unknown size, estimates of frequency cannot be made and a causal
relationship cannot be precisely established
Dr Cameron Durrant, Pharmacias vice president of infectious diseases,
told Reuters Health that the company had received about 40 reports of
adverse events by late 2000, when it notified the FDA of the new
information
Dr Durrant stressed that, although the company had already observed some
incidents of thrombocytopenia during Zyvoxs phase III clinical trials,
postmarketing surveillance uncovered additional cases of anemia, triggering
the need for strengthened labeling Zyvoxs label already warns of a
possible risk of thrombocytopenia
Dr Durrant added that the anemia cases occurred in patients who were being
treated with Zyvox for a longer period than patients who took part in Zyvox
clinical studies
He emphasized that the cases of anemia were mild and reversible and do
not change what the physician currently is directed to do in monitoring
Zyvox patients In any case, most of the
postmarket reports involved cases
of thrombocytopenia, he said
The FDA approved Zyvox in April 2000 for the treatment of vancomycin-
resistant Enterococcus faecium infections, nosocomial pneumonia and
community-acquired pneumonia and complicated and uncomplicated skin and
skin-structure infections
