primary side effects associated with protamine sulfate are temporary hypotension,
bradycardia, and dyspnea.
(1) Heparin Sodium, Heparin Calcium. Commerical heparin (unfractionated
heparin) comes from beef lung or pork intestinal mucosa. It is dosed in "units" and
measured in the lab by the partial thromboplastin time (PTT). Although some heparin is
administered in a "fixed dose" for prophylaxis against clots, it is more often administered
in a "wt-based" fashion for prophylaxis and treatment of clots. Therapeutic dose goals
are 1.2-1.5x the PTT control. Doses, especially for continuous infusion are adjusted to
meet this goal. Heparin may be administered in a very small fixed dose (10-100 units)
to clear intravenous ports in patients with long term IV lines. This dose is called a
"heparin flush". The absorption of subcutaneous heparin is unpredictable.
(2) Enoxaparin (Lovenox), Dalteparin (Fragmin). Enoxaparin and
dalteparin are two of several "low molecular weight heparins (LMWH)" (fractionated
heparin). They differ from unfractionated heparin by having more predictable
subcutaneous absorption, a longer duration of action, and primarily inhibit only one
clotting factor (Factor Xa). Either agent may be administered once or twice daily (SC)
usually for 7-10 days. The primary use for these agents is in the prevention and
treatment of deep vein thrombosis (leg clots) and pulmonary embolus (lung clots). The
sides effects are the same as with unfractionated heparin however they offer distinct
advantages in that the patient can self-administer these agents (discharged from the
hospital sooner), they do not require monitoring of the PTT, and are just as effective as
standard heparin. The major disadvantages are pain at the injection site and high cost.
c. Coumarin products. Coumarin products inhibit coagulation by interfering
with the incorporation of vitamin K into vitamin-K dependent clotting factors (Factors II,
VII, IX, and X). Their initial and maximum effect is based on the half-lives of each of
these factors. For example, Factor VII has a half-life of 6 hours so the effect of
coumarin on this factor will increase the bleeding to a certain degree within 6 hours,
however Factor II and X exhibit half-lives of 48-72 hours, so the maximum effect of
coumarin is not seen until 3 days after initiation or dose change. It does not matter
whether the drug is given orally or intravenously, it takes the same amount of time to
reach the maximum effect (essentially you cannot load a patient on coumarin agents).
Coumarin products do not dissolve clots but prevent clots from forming (prophylaxis)
and getting larger. The degree of anticoagulation is measured by a blood sample and
expressed as the prothrombin time (PT) or the International Normalized Ratio (INR).
The INR is the international standard. The therapeutic INR is generally between 2-3.5
which correlates with a 30-50% inhibition of vitamin K dependent clotting factors.
Ideally, the patient should have his/her INR checked every 4-6 weeks while on this
Warfarin sodium (Coumadin). Warfarin sodium is one of the most commonly
used anticoagulants (coumarins). It is used to prevent the extension of blood clots in
phlebitis or deep vein thrombosis and as a prophylactic agent in patients that have
mechanical heart valves (life-long therapy). The main side effect associated with the