COMBINATION OF COMBINATION OF DRUGSDRUGS

COMBINATION OF COMBINATION OF DRUGSDRUGS

DR. SHABANA ALIDR. SHABANA ALI

Combination of drugs• Two or > two drugs = effect

modified

EffectAction of drug Or Interaction at PK or PD level

SynergismDrug A + Drug B = action

synergistic

Both Drugs may have same actions or one drug may be inactive (given alone)

Types of Synergisma) Summation (addition)b) Potentiation (supra-additive)

a) SummationCombined effect of two drugs = sum

of effects (drugs given separately) cont.

Drugs acting on same receptors or having same mechanisms

e.g. combination of antacids, chemotherapeutic agents, diuretics; Ad + NA

Summation 1+1 = 2

b) Potentiation (supra-additive)

• Combined effects of two drugs = > sum of effects (drugs given separately)

• 1+1=>2E.g., sulphamethoxazole & trimethoprim =

bacteriostaticCo-trimaxozole= bactericidalAntihypertensive (captopril & diuretic);

tyramine + MAOI