These are drugs which inhibit plasminogen activation and dissolution of clot.
ANTIFIBRINOLYTICS
These are drugs which inhibit plasminogen activation and
dissolution of clot.
Epsilon Aminocaproic Acid (EACA)
It is an analogue of the amino acid lysine: combines
with the lysine binding sites of plasminogen and plasmin so that the latter is
not able to bind to fibrin and lyse it. It is a specific antidote for
fibrinolytic agents and has been used in many hyper-plasminaemic states
associated with excessive intravascular fibrinolysis resulting in bleeding,
e.g.:
·
Overdose of streptokinase/urokinase/alteplase.
·
To prevent recurrence of subarachnoid and g.i.
haemorrhage.
· Certain traumatic and surgical bleedings (prostatectomy,
tooth extraction in haemophiliacs).
· Abruptio placentae, PPH and certain cases of
menorrhagia.
However, the usefulness of EACA in most of the above conditions
is equivocal, except in overdose of fibrinolytics. In haematuria it can cause
ureteric obstruction by the unlysed clots. Therefore, fibrinolysis must be
established firmly before using it. It can cause intravascular thrombosis.
Rapid i.v. injection results in hypotension, bradycardia and may be arrhythmias.
It should be used cautiously when renal function is impaired. Myopathy occurs
rarely.
Initial priming dose is 5 g oral/i.v., followed by 1 g hourly till
bleeding stops (max. 30 g in 24 hrs).
AMICAR, HEMOCID, HAMOSTAT 0.5 g tab., 1.25 g/5 ml syr., 5 g/20
ml inj.
Tranexaemic Acid
Like EACA, it binds to the lysine binding site on
plasminogen and prevents its combination with fibrin and is 7 times more potent.
It has been used for prevention of excessive bleeding in:
·
Overdose of fibrinolytics
·
After cardiopulmonary bypass surgery.
·
After tonsillectomy, prostatic surgery, tooth
extraction in haemophiliacs.
·
Menorrhagia, specially due to IUCD.
·
Recurrent epistaxis, ocular trauma, bleeding
peptic ulcer.
Main side effects are
nausea and diarrhoea. Headache, giddiness and thrombophlebitis of injected vein
are other adverse effects.
Dose: 10–15 mg/kg 2–3 times
a day or 1–1.5 g TDS oral, 0.5–1 g
TDS by slow i.v. infusion.
CYCLOKAPRON 500 mg
tab, 100 mg/ml inj.
Aprotinin
It is a polypeptide isolated
from bovine tissues with polyvalent serine
protease inhibitory activity: trypsin, chymotrypsin, kallikrein and plasmin are
inhibited. It can be administered only i.v. and has a t½ of 2 hr. It has been
employed in selected situations:
Administered at the
beginning of cardiopulmonary bypass surgery—it reduces blood loss.
Traumatic,
haemorrhagic and endotoxic shock—has adjuvant value.
Acute pancreatitis
(trypsin may be released in circulation which may be fatal).
Fibrinolytic states, prostatic
surgery, carcinoid: may afford symptomatic relief.
Renal toxicity and
ischaemic events like MI and stroke are the possible adverse effects.
Dose: 5 lac KIU (Kallikrein
inactivator unit) initially, followed
by 2 lac KIU every 4 hr, all as slow i.v. infusion; TRASYLOL INF 5 lac KIU
in 50 ml inj; APROGEN 1 lac KIU (10 ml) and 5 lac KIU (50 ml) inj.
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