Parenteral drug products

Parenteral drug products

Introduction

Parenteral drug products are the dosage forms intended for administration by a route that does not involve the gastrointestinal (GI) tract (thus, parenteral). Most of the parenteral drug products are injectable dosage forms that are intended for administration by injection using a syringe and a needle.

Parenteral dosage forms are preferred for one or more of the following reasons:

·           Low oral bioavailability and/or high variability in oral drug absorption.

·           Instability of the drug in the GI tract. For example, most protein drugs are highly unstable.

·           Rapid onset of drug action is desired.

·           Ability to immediately stop drug administration is important. For example, most emergency room medications and anesthetics.

·           High degree of flexibility in dosage adjustment with or without real-time patient physiological response is needed. For example, emer-gency medications such as analgesics, anticancer drugs, and fertility medications.

Many drugs are available only as parenteral dosage forms. These include most protein and peptide drugs, some antibiotics, heparin, lidocaine, prot-amine, glucagon, and many anticancer compounds. Certain drugs, on the other hand, are available both as parenteral and oral dosage forms for dif-ferent clinical settings. For example, analgesics and antihistamine drugs for patient self-administration may be available as oral tablets, whereas they are also available as infusions and injections for use in an emergency room or hospital settings where rapid onset of drug action may be desired. Similarly, hormonal drugs, such as progestins and antiprogestins, are avail-able as tablets for use in contraception, and are also available as injectable dosage forms for use in fertility therapy.