Intravenous form

Levothyroxine (Synthroid , Levoxyl , Unithroid ), other brands, and generics Synthetic LT4 25, 50, 75, 88, 100, 112, 125, 137, 150, 1 75, 200, and 300 meg tablets 500 meg vial for injection 60 meg Gold standard for treating hypothyroidism products not therapeutically equivalent full replacement dose 1-1.6 meg/kg per day when switching from animal product, lower calculated daily dose by 25-50 meg intravenous form rarely needed... 

Use of intravenous colchicine to circumvent adverse gastrointestinal effects is discouraged due to the increased risk of serious and potentially fatal systemic effects with this route. The intravenous form should not be used in patients with moderate or more severe renal impairment (creatinine clearance less than or equal to 50 mL/minute), and total doses should not exceed 4 mg in a 7-day period. The potential extravasation of intravenous colchicine is also a concern. 

Anaphylactoid reactions, leukopenia, and seizures (intravenous form) have been reported. 

Diltiazem appears to be similar in efficacy to verapamil in the management of supraventricular arrhythmias, including rate control in atrial fibrillation. An intravenous form of diltiazem is available for the latter indication and causes hypotension or bradyarrhythmias relatively... 

Tacrolimus can be administered orally or intravenously. The half-life of the intravenous form is approximately 9-12 hours. Like cyclosporine, tacrolimus is metabolized primarily by P450 enzymes in the liver, and there is potential for drug interactions. The dosage is determined by trough blood level at steady state. Its toxic effects are similar to those of cyclosporine and include nephrotoxicity, neurotoxicity, hyperglycemia, hypertension, hyperkalemia, and gastrointestinal complaints. 

Mycophenolate mofetil is available in both oral and intravenous forms. The oral form is rapidly metabolized to mycophenolic acid. Although the cytochrome P450 system is not involved, some drug interactions still occur. Plasma drug levels are frequently monitored, similar to the calcineurin inhibitors and PSIs. 

These agents appear to be similar in efficacy to verapamil in the management of supraventricular arrhythmias, including rate control in atrial fibrillation. An intravenous form of diltiazem is available for the latter indication and causes hypotension or bradyarrhythmias relatively infrequently. Bepridil also has action potential- and QT-prolonging actions that theoretically may make it more useful in some ventricular arrhythmias but also create the risk of torsade de pointes. Bepridil is only rarely used, primarily to control refractory angina. 

Giving intravenous phosphate is probably the fastest and surest way to reduce serum calcium, but it is a hazardous procedure if not done properly. Intravenous phosphate should be used only after other methods of treatment (pamidronate, calcitonin, saline diuresis with furosemide, and plicamycin) have failed to control symptomatic hypercalcemia. Phosphate must be given slowly (50 mmol or 1.5 g elemental phosphorus over 6-8 hours) and the patient switched to oral phosphate (1-2 g/d elemental phosphorus, as one of the salts indicated below) as soon as symptoms of hypercalcemia have cleared. The risks of intravenous phosphate therapy include sudden hypocalcemia, ectopic calcification, acute renal failure, and hypotension. Oral phosphate can also lead to ectopic calcification and renal failure if serum calcium and phosphate levels are not carefully monitored, but the risk is less and the time of onset much longer. Phosphate is available in oral and intravenous forms as the sodium or potassium salt. Amounts required to provide 1 g of elemental phosphorus are as follows ... 

It is unlikely that an intravenous form of the drug will be available at launch. 

There is a higher incidence of ifosfamide encephalopathy associated with the oral form compared with the intravenous form of ifosfamide this has been attributed to metabolic differences between the two (16). 

The intravenous formulation of tetracycline was instilled intrapleurally to produce chemical pleurodesis, with good effect, from the 1970s to the 1990s. The adverse effect most commonly seen with tetracycline was chest pain, which was often severe (171,172). In a comprehensive review of intrapleural therapy published in 1994 (173) the incidence of chest pain was estimated at 14%, and fever occurred in 10% of patients. However, the intravenous form of tetracycline has been withdrawn by the manufacturer and so this agent is no longer available for pleurodesis. 

Ingestion is the most common route of accidental and intentional exposure to yohimbine. The substance is extracted from the bark of the tree Cory-nanthe yohimbe. This tree is found in western Africa. The powder form may also be smoked or steeped into a tea. It is available in an intravenous form for veterinary purposes. 

The fraction of a drug that is absorbed into the systemic circulation is referred to as its bioavailability. The bioavail-abflity (/) of a given drug is usually calculated by comparing, in the same subjects, the area under the plasma concentration-time curve (AUC) of an equivalent dose of the intravenous form and oral form... 

Chemically solubilized active principles render possible the preparation of parenteral, and especially intravenous forms appreciated in the clinical practice. But even at the preclinical level, the use of water-soluble molecules is recommended as they are effectively much easier to study by in vitro tests, in cell or microorganism cultures and on isolated organs. The inconveniences are that chemically modified sfructures may show modified pharmacological, pharmacokinetic and toxicological properties. 

Therapy should be initiated with the oral or intravenous form of acetylcysteine within 10 hours of ingestion when indicated. The oral liquid was the only approved form of acetylcysteine in the United States until the Food and Drug Administration (FDA) approved an intravenous form in 2004. Besides the means of administration, there are several notable differences (Table 10-10). The 20-hour dosage regimen for the intravenous form is based on one used in Europe for two decades and has similar outcome to the 72-hour oral regimen. The preference for the oral or intravenous form of acetylcysteine will evolve during the next few years of experience. 

The pharmacokinetics of the antiarrhythmic agents are summarized in Table 17-4, and a nomogram for estimating effective dosages of the oral forms (except amiodarone) is shown in Fig. 17-5. Dosing recommendations for the intravenous forms are shown in Table 17-5. 

A) Oral bioavailability is affected by first-pass hepatic metabolism Only third-generation cephalosporins cross the blood-brain barrier Procaine penicillin G is the most commonly used intravenous form of the antibiotic Renal tubular reabsorption of beta-lactams is inhibited by probenecid Nafcillin and ceftriaxone are eliminated mainly via biliary secretion The mechanism of antibacterial action of cephalosporins involves (A) Inhibition of the synthesis of precursors of peptidoglycans Interference with the synthesis of ergosterol Inhibition of transpeptidation reactions Inhibition of beta-lactamases Binding to cytoplasmic receptor proteins... 

In patients who may be highly susceptible to the adverse effects of traditional NSAIDs and COX-inhibitors, acetaminophen is a favorable alternative. Acetaminophen is a commonly used analgesic and antipyretic that is readily available in its oral form as an over-the-counter drug. It is also known as paracetamol or JV-acetyl-para-aminophenol (APAP), and is supplied in oral, rectal, and parenteral forms. Although the intravenous form has been available in various countries worldwide since 2002, it is currently still undergoing approval by the US Food and Drug Administration at the time of writing of this chapter. 

Synthetic glucocorticoids are indicated for a wide variety of conditions including rheumatoid arthritis, asthma, ankylosing spondylitis, lupus erythematosus, inflammatory bowel disease, dermatitis, allergic reaction, etc. These steroids are available in a variety of formulations allowing for oral, topical, inhalation and intravenous forms. Typical examples of synthetic glucocorticoids include betamethasone, cortisone acetate, deflazacort. 

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