DRUGS ACTING ON BLOOD AND BLOOD FORMING ORGANS
PREPARED BY MR. ABHIJIT DAS
HEMATINIC AGENTS
DEFINITION
Hematinic agents are medications or supplements that
help in the formation of red blood cells or improve the production of
hemoglobin, which is essential for carrying oxygen in the blood. These agents
typically contain iron, vitamin B12, or folic acid, and they are commonly used
to treat various types of anemia.
CLASSIFICATION
1.
Iron supplements: These agents contain
iron and are used to treat iron-deficiency anemia.
Examples: Ferrous
sulfate, ferrous gluconate, and ferrous fumarate.
2.
Vitamin B12 supplements: These agents
provide vitamin B12 and are used to treat pernicious anemia or other conditions
resulting from vitamin B12 deficiency.
Examples: Cyanocobalamin
and methylcobalamin.
3.
Folic acid supplements: These agents
contain folic acid and are used to treat folate-deficiency anemia.
Examples: Folic acid and
various folate derivatives.
4.
Combination supplements: Some hematinic
agents combine iron, vitamin B12, and folic acid to address multiple
deficiencies and support overall red blood cell production.
Examples: Combination
formulations like ferrous sulfate with folic acid and cyanocobalamin.
ANTICOAGULANTS
DEFINITION
Anticoagulants are medications that prevent blood
clot formation, reducing the risk of blood clots and promoting blood flow.
CLASSIFICATION
A. Parenteral
anticoagulants: heparin, low molecular weight heparin.
B. Oral
anticoagulants:
i.
Coumarin derivatives:
bishydroxycoumarin(dicumarol), warfarin sod, acenocoumarol(nicoumalone).
ii.
Indandione derivative: phenindione
HEPARIN
MOA
It enhances the activity of antithrombin, a natural
protein in the blood. By doing so, heparin helps antithrombin
in its role to inhibit clotting factors, specifically thrombin
and factor Xa, preventing the formation of blood clots.
(Clotting factor Xa is a key component of the blood coagulation process. It is
an enzyme that plays a crucial role in the formation of blood clots. When
activated, factor Xa converts prothrombin into thrombin, which then helps
convert fibrinogen into fibrin, a mesh-like protein that forms the basis of
blood clots.)
ADVERSE EFFECTS
1.
Bleeding: Heparin can make you more
prone to bleeding, from mild bruising to serious internal bleeding.
2.
Heparin-induced Thrombocytopenia (HIT):
Sometimes, heparin triggers a condition where your platelet levels drop,
increasing the risk of clotting.
3.
Osteoporosis: Long-term use of heparin
may weaken your bones and increase the risk of fractures.
THERAPEUTICAL USES
1.
Preventing and treating blood clots:
Heparin is widely used to prevent and treat blood clots in various conditions
like deep vein thrombosis, pulmonary embolism, and during surgeries where clotting
risks are high.
2.
During dialysis: Heparin is often used
during hemodialysis to prevent clotting in the bloodlines and the dialysis
machine, ensuring a smooth and effective treatment.
3.
Heart attacks and unstable angina:
Heparin is given in combination with other medications during certain heart
conditions to prevent further clot formation and improve blood flow to the
heart.
WARFARIN
MOA
It works by inhibiting the
synthesis of vitamin K-dependent clotting factors in the liver. By doing
so, warfarin interferes with the blood clotting process and helps prevent the
formation of blood clots.
{Examples of vitamin K-dependent clotting factors include:
1.
Prothrombin (Factor II): Prothrombin is
a precursor to thrombin, an essential enzyme in the blood clotting cascade.
2.
Factor VII (Proconvertin): Factor VII
activates Factor X, which plays a central role in the clotting process.
3.
Factor IX (Christmas Factor): Factor IX
activates Factor X, contributing to the formation of fibrin and blood clotting.
4.
Factor X (Stuart-Prower Factor): Factor
X is a key component in converting prothrombin to thrombin, which leads to the
formation of fibrin.}
ANTI-PLATELET AGENTS
DEFINITION
Antiplatelet drugs are medications that help prevent blood platelets from
sticking together and forming clots, reducing the risk of blood vessel
blockages and certain cardiovascular conditions.
ASPIRIN
MOA
Aspirin works as an antiplatelet agent by blocking
the COX-1 enzyme in platelets, which reduces the production of thromboxane A2.
This prevents platelet aggregation and helps prevent blood clot formation.
CLOPIDOGREL
MOA
Clopidogrel acts as an antiplatelet drug by blocking
ADP receptors on platelets, reducing platelet activation and preventing blood
clot formation in individuals at risk of cardiovascular events or after certain
medical procedures.
{ ADP receptors, also known as P2Y12 receptors, are cell
surface receptors found on platelets, which are small cell fragments in the
blood involved in clot formation. These receptors are part of the purinergic
receptor family and play a crucial role in platelet activation.
When platelets are activated due to blood vessel
injury or other factors, ADP is released from damaged cells and platelets
themselves. ADP binds to the P2Y12 receptors on nearby platelets, initiating a
signaling pathway that promotes platelet aggregation and clot formation. This
activation leads to a change in the shape and stickiness of platelets, making
them more likely to adhere to each other and form a clot at the site of injury.}
ADVERSE EFFECTS
1.
Bleeding: The most significant concern
with antiplatelet medications like clopidogrel is an increased risk of
bleeding. Since clopidogrel inhibits platelet aggregation, it can make it
harder for blood to clot, leading to potential bleeding issues. Severe bleeding,
although rare, can occur and may manifest as gastrointestinal bleeding,
nosebleeds, or easy bruising.
2.
Gastrointestinal Upset: Some individuals
may experience gastrointestinal side effects such as nausea, vomiting,
indigestion, or abdominal discomfort while taking clopidogrel.
3.
Allergic Reactions: In rare cases,
clopidogrel can trigger allergic reactions, which may range from mild skin
rashes to more severe allergic responses like swelling of the face, tongue, or
throat, difficulty breathing, and anaphylaxis.
THERAPEUTICAL USES
1.
Prevention of Cardiovascular Events:
Clopidogrel is commonly used to reduce the risk of heart attacks, strokes, and
other cardiovascular events in patients with a history of atherosclerosis or
those who have undergone procedures like stent placement.
2.
Treatment of Acute Coronary Syndrome:
Clopidogrel is used in combination with other medications for the management of
acute coronary syndrome, such as unstable angina and non-ST-segment elevation
myocardial infarction (NSTEMI).
3.
Post-Cardiovascular Event Management:
After experiencing a heart attack or stroke, patients may be prescribed
clopidogrel as part of their long-term treatment to prevent further clot
formation and recurrent cardiovascular events.
THROMBOLYTIC DRUGS
DEFINITION
Thrombolytic drugs, also known as clot-busting drugs,
are medications used to dissolve or break down blood clots that have formed
within blood vessels.
STREPTOKINASE AND UROKINASE
MOA
Streptokinase activates plasminogen to form plasmin,
a powerful enzyme. Plasmin then breaks down fibrin, the protein that creates
blood clots, leading to clot dissolution and restored blood flow.