Nitrofurantoin tablets

Concheiro A, Vila-Jato JL, Martinez-Pacheco R, Seijo B, Ramos T. In Vitro-In Vivo correlations of eight nitrofurantoin tablet formulations effect of various technological factors. Drug Dev Ind Pharm 1987 13 501—516. 

A 27-year-old woman presents a prescription for nitrofurantoin tablets 50 mg q.d.s. for 3 days and asks to speak to the pharmacist. She explains that her GP has checked her urine with a coloured strip and diagnosed a urinary tract infection (UTI). She is suffering considerable discomfort on urination due to a burn-ing/stinging sensation and her GP has suggested she purchase some Effercitrate over the counter. A friend has recommended she also purchase cranberry extract tablets and the patient would like your advice. 

Conte, U., Colombo, P., Caramella, C. and La Manna, A. (1979) Sustained release nitrofurantoin tablets by direct compression. Farmaco [Prat], 34, 306-316. 

Nicotinic Acid Tablets (200 mg) Nicotinamide see Vitamin B3 Nifedipine Tablet Cores (10 mg) Nitrendipine Tablets (25 mg) Nitrofurantoin Tablet Cores (100 mg) Nitrofurantoin Tablets (100 mg) Norephedrine Syrup (40 mg/10 g) Nystatin Suspension (100,000 i.u./ml) Nystatin Tabet Cores (200 mg) Nystatin Tablets (50 mg and 100 mg)... 

J. L. Vila-Jato, A. Concheriro, and B. Seijo, Effect of aging on the bioavailability of nitrofurantoin tablets containing carbpol934, Drug Dev. Ind. Pharm. 13, 1315-1327(1987). 

Diluted Isosorbide Dinitrate Isosorbide Dinitrate Tablets Hethazolamide Tablets Nitrofurantoin Nitrofurantoin Tablets Nitrofurantoin Oral Suspension Procarbazine Hydrochloride Capsules... 

D., Microencapsulation of nitrofurantoin in poly( e-caprolactone) Tableting and in vitro release studies, Int. J. Pharm.. 35. 145-156, 1987. 

TR Bates, JM Young, CM Wu, HA Rosenberg. pH-dependent dissolution rate of nitrofurantoin from commercial suspensions, tablets and capsules. J Pharm Sci 63 643-645, 1974. 

Fig. 4 Mean cumulative urinary excretion of nitrofurantoin after oral administration of a 100-mg macrocrystalline capsule of fasting (O) and nonfasting ( ) subjects and a 100-mg microcrystalline tablet to fasting ( ) and nonfasting ( ) subjects. Vertical bars represent standard errors of the mean. (From Ref. 7.).

The effect of particle size reduction on the bioavailability of nitrofurantoin was shown in Fig. 4. The microcrystalline form (< 10 pm) is more rapidly and completely absorbed from the tablet dosage form than is the macrocrystalline form (74-177 pm) from the capsule dosage form. This is not a completely satisfactory illustration of the effect of particle size on the rate and extent of availability, since other manufacturing variables have not been held constant. Nevertheless, it does suggest some correlation between particle size, dissolution rate, and rate of availability. 

Particle size and particle size distribution studies are important for drugs that have low water solubility. Particle size reduction by milling to a micronized form increased the absorption of low aqueous solubility drugs such as griseofulvin, nitrofurantoin, and many steroids. Smaller particle size results in an increase in the total surface area of the particles, enhances water penetration into the particles, and increases the dissolution rates. With poorly soluble drugs, a disintegrant may be added to the formulation to ensure rapid disintegration of the tablet and release of the particles. 

The deliberate manipulation of particle size leads to a measure of control of activity and side-effects. Rapid solution of nitrofurantoin from tablets of fine particulate material led to a high incidence of nausea in patients, as local high concentrations of the dmg produce a centrally mediated nausea. Development of macrocrystalline nitrofurantoin (as in Macrodantin) has led to the introduction of a form of therapy in which the incidence of nausea is reduced. Capsules are used to avoid compression of the... 

Intramuscular administration of nitrofurantoin sodium may also be successful in metastatic seminoma, the drug apparently decreases the size of lung metastases thus improving the patient s condition . Owing to the low blood levels which are achieved with nitrofurantoin, all indications for its use aside from urinary tract infections have meanwhile been abandoned hence nitrofurantoin is used orally as well as parenterally for the treatment of urinary tract infections only. Intravenous use of nitrofurantoin does not produce higher urine levels than oral administration or intramuscular injection does . A comparison of all three modes of application has proved that orally-administered nitrofurantoin is absorbed completely and metabolized rapidly since maximum drug levels appear in the urine within thirty to sixty minutes after administration. To reduce the rate of side effects, enteric coated tablets may be administered. Numerous reports especially from Japan have led to the conclusion that such tablets are absorbed at a slower rate and are, therefore, probably better tolerated. On the other hand, it seems likely that adequate bacteriostatic levels cannot be achieved and hence a higher failure rate will ensue with this method. 

Reduction in particle size, however, is not always desirable. For example, Slow K tablets incorporate a matrix that slowly releases potassium in order to minimize GI tract irritation. Simularly, Macrodantin is a formulation of large crystals of nitrofurantoin, which will dissolve slowly and thereby minimize irritation. 

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