Download Drug Information Shellfish Allergy

ISSUE/QUESTION: If a patient is allergic to shellfish, is it safe for them to consume
a) Calcium supplement derived from oyster shell (e.g. Teva pharm Calcium 500 mg
(NPN = 80001408)
b) Glucosamine Sulfate derived from shrimp/crab exoskeleton (e.g. Webber Naturals
Glucosamine Sulfate 500 mg capsules NPN =80000082)?
SUMMARY OF FINDINGS:
There are different kinds of shellfish and each kind contains different allergy-causing
proteins [1].
Crustaceans: Crabs, lobster, crayfish, shrimp and prawn
Mollusks:
Bivalves: Clams, mussels, oysters and scallops
Gastropods: Limpets, periwinkles, snails (escargot) and abalone
Cephalopods: Squid, cuttlefish, octopus
Adverse reactions to shellfish can be either immunological or non-immunological and
can be triggered by parasites, bacteria, viruses, marine toxins and biogenic amines (e.g.
histamine) [2]. Some people can consume one type of shellfish but some others must
avoid all shellfish [1].
Gluosamine Sulfate: Drug information center for Webber Naturals was contacted and
the representative mentioned that the risk of anaphylactic reaction depends on sensitivity
of the patient [3]. He further mentioned that according to their monograph it is almost 0
% and it is a judgement call [3]. The crab exoskeleton goes through numerous chemical
modifications and purifications [3]. The representative forwarded the product monograph
in an email which is quoted below:
The Glucosamine Sulfate ingredient is manufactured using a compound derived
from the shells of crabs, shrimps, and prawns. Glucosamine Sulfate is a highly
purified ingredient and does not contain allergenic shellfish flesh proteins. We are
not aware of any allergic reactions to Glucosamine Sulfate in people with
shellfish allergies. Our product monograph contains the following information:
Precautions / Cautions
Those allergic to shellfish have been concerned over a possible allergic reaction to
glucosamine. Allergic reaction has not been reported as a practical concern,
probably because the allergens are in the meat and the extraction process is able to
denature any extraneous flesh protein. However, it must be recognized that
individuals sometimes display profound sensitivity where it is not expected. If
there is concern over possible allergic reaction, especially if anaphylactic
reactions are possible, have the customer discuss the matter with their physician
before commencing use [3].
Calcium Carbonate: The drug information center for Teva Pharm was contacted and the
representative mentioned that allergy to shellfish stems from allergy to protein in the fish
and oyster shells do not have any fish living in them for years and it goes through
purification process making it highly unlikely to cause any allergy [4]. However, she
advised to watch out the first time a patient consumes the product [4].
Upon doing a Google search I also found some information in the FAQ section of Os-Cal
(Calcium + Vit D3).
Generally, when a person is allergic to shellfish, they are allergic to a protein in
the fish. The oyster shells contained in Os-Cal are obtained by dredging only
ancient oyster beds in offshore U.S. waters. These fossilized shells haven't had
living oysters inside of them for thousands of years, and they are carefully ground
to a powder, which is the source of calcium carbonate. The oyster shell powder is
combined with pharmaceutical grade ingredients and subjected to rigorous testing
for safety and tolerability. This helps make sure that the calcium carbonate is in a
form that is readily ingested, disintegrated and metabolized by the human body.
Since the source of calcium carbonate for Os-Cal Calcium + D3 and Os-Cal Extra
D3 Caplets are taken from ancient oyster shell reefs and the shells are washed and
oven-dried before being milled to supply the calcium, it is very unlikely that any
of the protein allergens would be present [5].
BC Drug Poison & Information Center: The pharmacist at DPIC discussed different
types of shellfish, types of allergies and found similar information to what is listed above.
She added that no information was located in the references searched regarding case
reports of allergic reactions from use of ground up oyster shells [6].
RECOMMENDATION / CONCLUSION:
Considering the information received from the two companies, online search and DPIC, it
was concluded that the investigated products are safe to consume for someone with
shellfish allergy, however type of allergy should be confirmed and caution should be
taken the first time patient is exposed to the product in order to be safe.
References
1. Mayoclinic.com. Shellfish allergy [Internet]. June 23, 2011 [cited 2012 Jan 5].
Available from: http://www.mayoclinic.com/health/shellfish-allergy/DS00987
2. Lopata AL, O'Hehir RE, Lehrer SB. Shellfish allergy. Clinical & Experimental
Allergy. 2010; 40:850-858.
3. Nixon M. Webber Naturals Glucosamine Info [online]. E-mail to Rajwant Minhas
([email protected]) 2012 Jan 5 [cited 2012 Jan 5].
4. In a conversation with Teva Pharm (Jan 5, 2012)
5. GlaxoSmith Kline. Os-Cal FAQs [Internet]. [cited 2012 Jan 5]. Available from:
http://www.oscal.com/faq.aspx#a17.
6. McInnes K. Shellfish allergy and calcium supplements [online]. E-mail to Rajwant
Minhas ([email protected]) 2012 Jan 5 [cited 2012 Jan 5].