Penicillin injections suspension

Two basic methods are used to prepare parenteral suspensions (a) sterile vehicle and powder are combined aseptically, or (b) sterile solutions are combined and the crystals formed in situ. Examples of these procedures may be illustrated using Penicillin G Procaine Injectable Suspension USP and Sterile Testosterone Injectable Suspension USP. 

An essential property required to obtain a physically stable suspension formulation is that the drag substance has a low solubility in the suspension vehicle. This applies to all types of suspension whether intended for oral, parenteral or inhalation delivery. Since most suspensions are aqueous, a low solubility in water is required to prevent drug dissolution and crystal growth on storage. Some drugs intended for intramuscular use are formulated as suspensions in oil (e.g. penicillin injections are formulated in sesame oil) to improve chemical stability via a reduction in solubility. 

The formulation of aqueous injectable suspensions follows, in general, the same lines that were e.stablished when drugs such as cortisone, penicillin, or pro-caine were first prepared in this form. The main ingredients are, in addition to the active compound, wetting agents and protective colloids. As in the case of reconslitutable suspensions, polysorbate 80 is most frequently used to decrease the solid-liquid interfacial tension, this promoting the sustitution of a solid-air interface by a solid-water one. Another surfactant that is often employed is siv dium poly succinate. 

In contrast, parenteral suspensions have relatively low solids contents, usually between 0.5 and 5%, with the exception of insoluble forms of penicillin in which concentrations of the antibiotic may exceed 30%. These sterile preparations are designed for intramuscular, intradermal, intralesional, intraarticular, or subcutaneous injection. Syringeability is an important factor to be taken into consideration with injectable dosage forms. The viscosity of a parenteral suspension should be sufficiently low to facilitate injection. Common suspending vehicles include preserved isotonic saline solution or a parenterally acceptable vegetable oil. Ophthalmic and optic suspensions that are instilled into the eye/ear must also be prepared in a sterile manner. The vehicles are essentially isotonic and aqueous in composition. The reader should refer to Chapter 12 for further discussion on parenteral products. 

Penicillins are available in tablets, chewable tablets, capsules, powder for oral suspension, powder for injection, prefilled syringes for injection, premixed dextrose solutions for injection, and solutions for infusion. 

Co-amoxiclav consists of amoxicillin, a broad-spectrum penicillin, and clavu-lanic acid, a beta-lactamase inhibitor. It is available as tablets, an oral suspension and as an injection formulation. 

Special emphasis should be put on the precautionary measures to be taken when injecting long-acting penicillins or other drugs in crystalline suspensions intramuscularly. 

Penicillin is available in tablet and suspension form for oral use and in injectable form for intravenous and intramuscular use. Ingestion of tablets and the suspension forms are the most common poisoning exposures. 

Penicillin G procaine suspension is an aqueous preparation of the crystalline salt that is only 0.4% soluble in water. Procaine combines with penicillin mole for mole a dose of 300,000 units thus contains approximately 120 mg procaine. When large doses of penicillin G procaine are given (e.g., 4.8 million units), procaine may reach toxic concentrations in the plasma. If the patient is believed to be hypersensitive to procaine, 0.1 mL of 1% solution of procaine should be injected intradermally as a test. The anesthetic effect of the procaine accounts in part for the fact that injections of penicillin G procaine are virtually painless. 

Penicillin G benzathine suspension is the aqueous suspension of the salt obtained by the combination of 1 mol of an ammonium base and 2 mol of penicillin G to yield A/,A -dibenzylethylenediamine dipenicilhn G. The salt itself is 0.02% soluble in water. The long persistence of penicillin in the blood after a suitable IM dose reduces cost, the need for repeated injections, and local trauma. The local anesthetic effect of penicillin G benzathine is comparable with that of penicillin G procaine. 

Penicillin G procaine suspension combines procaine with penicillin in equimolar ratios a dose of 300,000 units contains -120 mg procaine, which exerts local anesthetic effects when injected. 

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