Concept:
Large volume parenterals are sterile preparations administered in large volumes, usually by intravenous route.
Step 1: Understanding preservatives.
Preservatives are added to prevent microbial growth in some formulations.
Step 2: Why they are avoided in LVPs.
Since LVPs are administered in large quantities, even a small concentration of preservative can result in a significant total amount entering the body.
Step 3: Toxicity concern.
This may cause toxicity, especially because LVPs are given directly into systemic circulation.
Step 4: Final answer.
Therefore, LVPs must be free from preservatives due to toxicity risk from large dose.
\[
\boxed{\text{Toxicity risk due to large dose}}
\]