Lecture presented 21st . June 2021 at Al-Mahmoudiya General Hospital By Drug Information Centre

1. Recommendations to switching betweenanticoagulants
Initial treatment Switch to Recommendation
UFH-heparin LMWH-
enoxaparin
 Stop heparin
 Start agent at time heparin infusion is
stopped-otherwise, for more conservative
strategy, start LMWH agent 2 hours after
heparin infusion is stopped
LMWH-
enoxaparin
UFH-
heparin
 Stop LMWH agent
 Start heparin infusion at time when next
doseof LMWH agent is due
UFH-Heparin (5000-25000U)vial
Regimen Dose Condition
Conventional I.V
bolus
5000-10000 U q4-6hr
(80-100 U/kg)
(75 U/kg) BNF
Treatment of mild - moderate
-severe PE, unstable angina,
acute peripheral arterial
occlusion, DVT
Maintenance I.V 750-1000 U/hr
(15-22 U/kg)
(18 U/kg) BNF
DeepS.C dose 10000-20000 U q8-12hr Treatment of DVT
Low dose S.C 5000 U q8-12 hr
5000-10000U q12hr
Thromboprophylaxis in
medical/surgical cases (taken
2hr before surgery and
continue for 7-10 days)
During pregnancy

2. Enoxaparin (2000-4000-6000IU)prefilled syringe
Regimen Dose Condition
S.C
prophylaxis
3000 IU q12hr
-4000 IU q24hr
2000 IU q24hr (BNF)
Prophylaxis of DVT,
moderate-high risk , medical
/surgical cases (1st dosetaken
2hr before surgery)
Full dose S.C
therapy
100IU/kg (1mg/kg) q 12 hr
159IU/kg (BNF)
Treatment of pt. with
obesity, symptomatic PE,
cancer, recurrent VTE or
proximal (vena iliaca)
thrombosis
4000IUq12hr--50kg
6000IUq12hr--50-69kg
8000IUq12hr--70-89kg
10000IUq12hr--above 90 kg
VTE in pregnancy,
(according to early
pregnancy weight)
150IU/kg q 24 hr Uncomplicated pt. with low
risk of VTE recurrence
I.V bolus 3000IU I.V bolus for STEMI
(S.C maintenance for STEMI
8 days & 2-8 non SEMI)
S.C
maintenance
100IU q12hr
Not recommended outside the prevention of
thrombus formation in dialysis pt.
End stage renal disease (Cr
Cl <15ml/min)
Differences in pharmacokinetics and efficacy
 LMWH are equally efficacious to UFH except during cardiopulmonary
bypass surgery, in which high doseUFH is still the preferred
anticoagulant, because LMW heparin are less effective in preventing
catheter thrombosis and their effects are not fully reversed by protamine
 LMWH provide better subcutaneous bioavailability than UFH
 LMWH have longer and more consistent half-life than UFH

3. In details comparison
UFH-heparin LMWH-enoxaparin
Biochemical
structure
Non-uniform mixture of
straight chain
mucopolysaccharides with
MW 10,000 to 20,000.
[contains polymers of two
sulfated disaccharide units]
Fractions of LMW
forms (MW 3000–7000)
Pharmacological
action
 Powerful and
instantaneously acting
anticoagulant, effective
both in vivo and in vitro.
 It acts indirectly by
activating plasma
antithrombin III (AT III, a
serine proteinase-
inhibitor, affecting the
clotting factors of the
intrinsic and common
pathways (Xa, IIa, IXa,
XIa, XIIa and XIIIa) and
inactivates them but not
factor VIIa operative in
the extrinsic pathway.
 At low concentrations,
factor Xa mediated
conversion of prothrombin
to thrombin is selectively
affected.
 in higher doses inhibits
platelet aggregation and
prolongs bleeding time.
 selectively inhibit factor
Xa with little effect on IIa
 LMW heparins have
smaller effect on aPTT
and whole blood clotting
time than unfractionated
heparin (UFH) relative to
antifactor Xa activity.
 Also they have lesser
antiplatelet action -less
interference with
haemostasis.
Severe drug
interactions
NSIAD, antiplatelets, biological agents (mab drugs),
antiepileptic & antidepressants, dyridamol,
Common drug
interactions
alteplase, apixaban, nicotinic acid, omega 3 fatty acid,
rivaroxaban, streptokinase, warfarin – increase bleeding
risk

4. amilioride, candesartan, captopril, enalapril, epoetin alfa,
heparin, KCl, spironolactone, trimethoprim, valsartan-
increase risk of hyperkalaemia
What to monitor platelets count (course <4 days), plasma K conc. (course<7
days) & anti-lfactor Xa activity (for enoxaparin only)
References
 KD Tripathy. Essential of Medical Pharmacology, 7th
Edition 2013
 BG Katzung. Basic and Clinical Pharmacology, 13th
Edition 2015
 Mosby’s drug reference for health professionals
 British national formulary 73 & v3.0.6 (828)
 Essentials of medical pharmacology 7th Ed.
 Drugs.com website
 Baghdad Health Directorate - Al-Karkh, department of pharmacy, pharmacovigilance unit.
Enoxaparin EMA updates no. 501 at 7th
Feb 2021.
 British National Formulary for android, v3.0.6, 2nd
Dec 2020
 Thrombophilia and Anticoagulation Clinic, Minneapolis Heart Institute, Abbott Northwestern
Hospital. Switching To and From Various Anticoagulants, 2016. Available from:
https://www.google.com/search?q=Switching+To+and+From+Various+Anticoagulants&oq=Swit
ching+To+and+From+Various+Anticoagulants&aqs=chrome..69i57.4526658j0j4&sourceid=chro
me&ie=UTF-8#
 Prandoni P,Carnovali M, Marchiori A; Galilei Investigators. Subcutaneous adjusted-dose
unfractionated heparin vs fixed-dose low-molecular-weight heparin in the initial treatment of
venous thromboembolism. Arch Intern Med. 2004 May 24;164(10):1077-83. Available from:
https://pubmed.ncbi.nlm.nih.gov/15159264/
 Hommes DW,Bura A, Mazzolai L, Büller HR, ten Cate JW. Subcutaneous heparin compared
with continuous intravenous heparin administration in the initial treatment of deep vein
thrombosis. A meta-analysis. Ann Intern Med. 1992 Feb 15;116(4):279-84. Available from:
https://pubmed.ncbi.nlm.nih.gov/1531108/#:~:text=Conclusions%3A%20The%20results%20of%
20our,as%20continuous%20intravenous%20heparin%20administration.