Low-dose preparations

The current consensus is that the contemporary low-dose preparations pose minimal risks in women who have no predisposing risk factors and, in fact, may provide certain beneficial health effects (e.g., protection against endometrial and ovarian cancer). Oral contraceptive pills have been associated with increased risk for myocardial infarction, stroke, and venous thromboembolism. However, studies have been published that suggest that these risks are minimal in appropriately chosen low-risk women. 

When the results of all the above analytical mediods are negative, diis information still may provide a useful clue to the possible identity of die sample. Homoeopathic and other low dose preparations should be considered. 

R = / -C H ), in low doses, exhibits the former behavior and is used primarily as an extradural agent in obstetrics. The lowest effective extradural concentration of etidocaine (21, X = CH, R = R = 2H, R = / -C H ), however, shows both adequate sensory and profound motor blockade so that it is useful in surgical situations where maximum neuromuscular blockade is necessary. In an isolated nerve preparation, bupivacaine blocks unmyelinated C fibers which are mainly responsible for pain perception at a much greater extent than the myelinated A fibers which carry motor impulses. It is postulated that absorption of bupivacaine by the vasculature at the site of injection, combined with the slow diffusion of this agent, results in an insufficient amount of the drug penetrating the large A fibers to cause motor conduction blockade. Clinically, motor block can be observed in some procedures. 

Croton oil is an extract of the seed of the plant Croton tiglium and has been commercially prepared as Croton resin since 1932. Its activity on the skin is related to free hydroxyl groups, which cause skin vesiculation even in low doses. 

Homeopathic remedies are very low dose therapeutical preparations produced from different source materials/substances (e.g. extracts from plants or animal tissues, animal secretions, minerals or chemical substances). The source substances are processed and diluted with water under defined conditions. The diluted homeopathic remedy (also called preparation) is then applied to the animal orally either as a liquid or after application of the remedy onto... 

A review of evidence supported the use of pure THC preparations to treat nausea associated with cancer chemotherapy and to stimulate appetite (Voth and Schwartz 1997). In patients with anorexia due to advanced cancer, THC (2.5 mg PO tid) was effective in stimulating appetite and was well tolerated at low doses (Nelson et al. 1994). 

In low doses, harhiturates act as sedatives. Barbiturates are made from harhituric acid, a weak monoprotic acid that was first prepared by the German chemist Adolph von Baeyer in 1864. The formula... 

The same liposomal preparation was used to investigate the effect of the administered dose on the biodistribution and pharmacokinetics (41). The effect of the lipid dose of Tc-HYNIC-PEG-liposomes was investigated in the low-dose range (0.02-1.0 pmol/kg), typically for noninvasive imaging applications. The biodistribution and pharmacokinetics of "Tc-HYNIC-PEG-liposomes at various dose levels were studied in rats and rabbits with a focal Escherichia coli infection. Moreover, the pharmacokinetics of Tc-HYNIC-PEG-liposomes at two lipid dose levels were studied in four patients. In rabbits, enhanced clearance was observed at a dose level of 0.02 pmol/kg. The circulatory half-life decreased from 10.4 to 3.5 hours (at 1.0 and 0.02 pmol/kg, respectively). At the lowest dose level, liposomes were mainly taken up by the liver and to a lesser extent by the spleen. Most importantly, the rapid clearance of low-dose PEG liposomes was also observed in humans when relatively low lipid doses were administered as is shown in Figure 4. This study showed that, at very low lipid doses, the biodistribution of PEG liposomes is dramatically altered. 

Successful vaccines have several important properties such as safety, effectiveness, low cost per dose, and ease of preparation. Vaccines, whether peptide, protein, or DNA, have limited potency without codelivery with an adjuvant and/or a specialized delivery system (11). There is currently a lack of safe, nontoxic, effective. Food and Drug Administration (FDA)-approved vaccine adjuvants capable of stimulating cellular (Thl) immunity (12). Most potent immune activators are also toxic at relatively low doses and cannot, therefore, be successfully used as adjuvants (12). 

Minipill. Continuous low-dose administration of progestin alone can prevent conception. Ovulations are not suppressed regularly the effect is then due to progestin-induced alterations in cervical and endometrial function. Because of the need for constant intake at the same time of day, a lower success rate, and relatively frequent bleeding anomalies, these preparations are now rarely employed. 

High-dose monophasic preparations are indicated for the management of dysfunctional uterine bleedings and when persistent breakthrough bleedings occur with low-dose oral contraceptives. The monophasic combinations are taken in a fixed dose combination once daily over 21 or 22 days, followed by an interval of 7 or 6 days. 

Venlafaxine is a serotonin and noradrenaline reuptake inhibitor (SNRI). It shares these properties with the TCAs amitriptyhne, clomipramine and imip-ramine, but it is the first selective SNRI, with low affinity for muscarinic, histaminic and a-adrenergic receptors. At low doses serotonergic effects predominate, but at higher doses the reuptake of noradrenaline is significantly blocked (Melichar et al. 2001). It is available as immediate and extended release (XR) preparations. 

Diphenoxylate Lomotil) is a meperidine derivative used as an antidiarrheal. It exhibits no morphinelike effects at low doses, but it produces mUd opioid effects, such as sedation, euphoria, and dependence, at higher doses. Its salts are highly insoluble in water, which reduces recreational use. Preparations often include atropine. 

Inhaled glucocorticoid preparations, such as be-clomethasone dipropionate and betamethasone valerate, provide an effective alternative to systemic steroids in the treatment of chronic asthma, with lesser side effects than oral or parenteral glucocorticoids (see Chapter 39). In fact, inhaled glucocorticoids have become a mainstay of asthma therapy. Inhalation delivers the agent directly to the target site in relatively low doses, with the potential for more frequent administration. Moreover, inhaled glucocorticoids are metabolized in the lung before they are absorbed, which reduces their systemic effects. However, even modest doses of... 

A low dosage of progestin ( mini-pill ) is used, in the form of medroxyprogesterone acetate, which is active at a very low dose. The mini-pill does not inhibit ovulation, but rather interferes with the endometrium and the cervical mucus. The use of this pill prevents most of the side effects of oral contraception, specifically nausea, water retention, and in some cases thrombophlebitis. However, a lower success rate and other frequent side effects have reduced the widespread acceptance of this preparation. Nevertheless, the mini-pill has a role to play in certain specific situations. For example, in an uncommon form of epilepsy called catamenial epilepsy, female patients will experience seizures at particular times during their menstrual cycle, reflecting the fact that seizure focus is stimulated by estrogens but inhibited by progestins. In such women, the mini-pill may afford not only birth control but also improved seizure control. 

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