Page 53 - Dosage 1-part2 -ebook_Neat

30/10/2025, 00:02 Pharmaceutical Solutions & Sterile Dosage Forms

Foreign bodies are non-biodegradable, if injected will accumulate:

IM: muscle granuloma.
IV: Embolism (thrombosis); Fatal

4. pH

Ideal pH for parenteral preparations is 7.4

HOWEVER, some injected drugs require different pH values than neutrality (WHY?)
(Some drugs are insoluble at pH 7.4, others are unstable at this pH)

Formulate at the suitable pH for the stability or solubility.
Add a buffer system of low buffering capacity (WHY?)

Allow rapid neutralization of the SVP by the natural buffer systems.

I. Non-neutral SVP (IM, SC, IV)

Buffers used: Acetate (1-2%), phosphate (0.8-2%) and citrate (1-5%) buffers.
The acceptable pH range for non-neutral SVP is 4-9 for tissues (routes other than IV)
Body tissues: Higher or lower values are very irritant and damaging to sensitive cells.

NOTE: Borate buffer use in parenteral formulations is forbidden (Toxicity issues).

II. Non-neutral LVP

IV infusions should not contain buffering system (WHY??)
Large volume needs large amount of buffer (toxicity).
Full neutralization of large amounts of buffer is difficult even if low buffer capacity is
used).

Any decrease or increase in blood pH can result in systemic acidosis or alkalosis (life threatening) 50/77

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